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diff --git a/hw6/src/areaLightsource.cpp b/hw6/src/areaLightsource.cpp
new file mode 100644
index 0000000..9005939
--- /dev/null
+++ b/hw6/src/areaLightsource.cpp
@@ -0,0 +1,87 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "constants.h"
+#include "areaLightsource.h"
+
+//////////////////
+// Constructors //
+//////////////////
+areaLightsource::areaLightsource(const color& power, const std::shared_ptr<const boundedPrimitive>& geometry, const vec3d& attenuation)
+{
+  _power = power;
+  _geometry = geometry;
+  _attenuation = attenuation;
+
+  if(_geometry)
+  {
+    _center = _geometry->sample(0.5f, 0.5).position();
+    _area = _geometry->area();
+  }
+}
+
+
+/////////////
+// Methods //
+/////////////
+lightSample areaLightsource::intensityAt(const vec3d& point) const
+{
+  // use the 'center position' and emulate a point light source
+  vec3d direction = point - _center;
+  float distance = direction.length();
+  float attenuation = ((_attenuation[2]*distance + _attenuation[1])*distance + _attenuation[0]);
+
+  // Done.
+  return lightSample(direction, _power / attenuation, distance - 2.0f * EPSILON);  // reduce distance to avoid self-intersection
+}
+
+
+lightSample areaLightsource::emittanceAt(const vec3d& point, float r1, float r2) const
+{
+  if(!_geometry) return lightSample();
+
+  // sample surface
+  surfaceSample sample = _geometry->sample(r1, r2);
+
+  // direction
+  vec3d direction = point - sample.position();
+  float distance = direction.length();
+
+  // handle backside case
+  if(direction.dot(sample.normal()) < 0.0f) return lightSample();
+
+  // Done.
+  return lightSample(direction,
+		     _power / (2.0f * PI * _area),
+		     distance - 2.0f * EPSILON,     // reduce distance to avoid self-intersection
+		     sample.pdf(),
+		     direction.dot( sample.normal() ) / distance);
+}
+
+
+color areaLightsource::_emittance(const intersectionPoint& ip) const
+{
+  // check if back hit
+  // Note: ip.direction toward the intersection point
+  if(ip.normal().dot(ip.direction()) > 0.0f) return color();
+
+  // evaluate emittance (assume point lies on light source)
+  return _power / (2.0f * PI * _area);
+}
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void areaLightsource::_print(std::ostream& s) const
+{
+  if(_geometry)
+    s << "Area Lightsource: power=" << _power << ", attenuation=" << _attenuation << ", area=" << _area << " centered at: " << _center;
+  else s << "Invalid Area Lightsource";
+}
+
diff --git a/hw6/src/bilinearTexture.cpp b/hw6/src/bilinearTexture.cpp
new file mode 100644
index 0000000..f9697bf
--- /dev/null
+++ b/hw6/src/bilinearTexture.cpp
@@ -0,0 +1,69 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "bilinearTexture.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+bilinearTexture::bilinearTexture(bool repeat)
+  : texture_base(repeat)
+{
+  // Do nothing.
+}
+
+
+bilinearTexture::bilinearTexture(const bilinearTexture& src)
+  : texture_base(src)
+{
+  // Do nothing
+}
+
+
+///////////////
+// Operators //
+///////////////
+bilinearTexture& bilinearTexture::operator=(const bilinearTexture& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+image::value_type bilinearTexture::operator()(const vec2d& textureCoord) const
+{
+  float scaled_u = textureCoord.u*(width()-1);
+  float scaled_v = textureCoord.v*(height()-1);
+
+  // compute corners
+  signed int left = floor(scaled_u);
+  signed int right = ceil(scaled_u);
+  signed int top = floor(scaled_v);
+  signed int bottom = ceil(scaled_v);
+
+  // compute weights
+  float hw = fabs(right - scaled_u);
+  float vw = fabs(bottom - scaled_v);
+
+  // compute horizontal interpolated colors
+  color topColor = hw * _at(left, top) + (1.0f - hw) * _at(right, top);
+  color bottomColor = hw * _at(left, bottom) + (1.0f - hw) * _at(right, bottom);
+
+  // interpolate vertically
+  return vw * topColor + (1.0f - vw) * bottomColor;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void bilinearTexture::_print(std::ostream& s) const
+{
+  s << "Bilinear texture (" << this->width() << "x" << this->height() << ")";
+}
diff --git a/hw6/src/boundedCompound.cpp b/hw6/src/boundedCompound.cpp
new file mode 100644
index 0000000..c37ca0f
--- /dev/null
+++ b/hw6/src/boundedCompound.cpp
@@ -0,0 +1,139 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include <algorithm>
+
+#include "boundedCompound.h"
+#include "intersector_factory_base.h"
+
+/////////////////
+// Constructor //
+/////////////////
+boundedCompound::boundedCompound(void)
+  : boundedPrimitive()
+{
+  _transform = transformation3d();
+  _intersector = nullptr;
+}
+
+
+boundedCompound::boundedCompound(const transformation3d& transform, const std::shared_ptr<const shader_base>& shader)
+				 
+  : boundedPrimitive(boundingBox(), shader)
+{
+  _transform = transform;
+  _intersector = nullptr;
+}
+
+
+/////////////
+// Methods //
+/////////////
+intersectionPoint boundedCompound::intersect(const ray& r) const
+{
+  // sanity check
+  assert(_intersector);
+
+  // inverse transform ray
+  ray transformedRay = inverseTransform(r, _transform);
+
+  // pass intersection computation to _intersector
+  intersectionPoint ip = _intersector->intersect( transformedRay );
+
+  // if no shader, insert current shader
+  if(!ip.hasShader()) ip.setShader(_shader);
+
+  // transform the intersection point
+  ip.transform(_transform);
+
+  // Done.
+  return ip;
+}
+
+
+float boundedCompound::area(void) const
+{
+  float total_area = 0.0f;
+  for_each(compounds().begin(), compounds().end(), [&](const std::shared_ptr<const boundedPrimitive>& prim)
+  {
+    total_area += prim->area();
+  });
+
+  // Done.
+  return total_area;
+}
+
+
+surfaceSample boundedCompound::sample(float r1, float r2) const
+{
+  float total_area = area();
+  auto primItr = compounds().begin();
+
+  // sample compounds (proportional to area)
+  float prim_area = (*primItr)->area();
+  float residual = r1*total_area;
+  while(residual > prim_area && std::next(primItr) != compounds().end())
+  {
+    residual -= prim_area;
+    primItr++;
+    prim_area = (*primItr)->area();
+  }
+
+  // rescale the random variable
+  r1 = std::min(residual / prim_area, 1.0f);
+
+  // sample point in triangle (and adjust pdf to include the above selection)
+  surfaceSample sample = (*primItr)->sample(r1, r2) * (prim_area / total_area);
+
+  // apply transformation
+  sample.transform(_transform);
+
+  // Done.
+  return sample;
+}
+
+
+void boundedCompound::initialize(const intersector_factory_base& ifb)
+{
+  // create the _intersector
+  _intersector = ifb(*this);
+}
+ 
+
+void boundedCompound::initializeBoundingBox(void)
+{
+  // compute the bounding box in world coordinates
+  _bb = boundingBox();
+  for_each(compounds().begin(), compounds().end(), [&](const std::shared_ptr<const boundedPrimitive>& prim)
+  {
+    _bb += transform(prim->boundingbox(), _transform);
+  });
+}
+
+
+bool boundedCompound::hasShader(void) const
+{
+  // check if this has a shader
+  if(boundedPrimitive::hasShader()) return true;
+
+  // check if each child has a shader
+  for(auto itr = compounds().begin(); itr != compounds().end(); itr++)
+  {
+    if(!(*itr)->hasShader()) return false;
+  }
+
+  // Done.
+  return true;
+}
+
+
+void boundedCompound::_print(std::ostream& s) const
+{
+  s << "boundedCompound (" << _bb << ", " << compounds().size() << " compounds)";
+}
diff --git a/hw6/src/boundedPrimitive.cpp b/hw6/src/boundedPrimitive.cpp
new file mode 100644
index 0000000..d328b16
--- /dev/null
+++ b/hw6/src/boundedPrimitive.cpp
@@ -0,0 +1,50 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "boundedPrimitive.h"
+
+/////////////////
+// Constructor //
+/////////////////
+boundedPrimitive::boundedPrimitive(void)
+{
+  _bb = boundingBox();
+  _shader = nullptr;
+}
+
+boundedPrimitive::boundedPrimitive(const boundingBox& bb, const std::shared_ptr<const shader_base>& shader)
+{
+  _bb = bb;
+  _shader = shader;
+}
+
+
+/////////////
+// Methods //
+/////////////
+const boundingBox& boundedPrimitive::boundingbox(void) const
+{
+  return _bb;
+}
+
+
+bool boundedPrimitive::hitBoundingBox(const ray& r) const
+{
+  return _bb.isHit(r);
+}
+
+
+bool boundedPrimitive::hasShader(void) const
+{
+  return (_shader != nullptr); 
+}  
+
+void boundedPrimitive::_print(std::ostream& s) const
+{
+  s << "boundedPrimitive (" << _bb << ")";
+}
diff --git a/hw6/src/boundedTriangle.cpp b/hw6/src/boundedTriangle.cpp
new file mode 100644
index 0000000..1119796
--- /dev/null
+++ b/hw6/src/boundedTriangle.cpp
@@ -0,0 +1,67 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "boundedTriangle.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+boundedTriangle::boundedTriangle(void)
+  : boundedPrimitive()
+{
+  // Nothing
+}
+
+boundedTriangle::boundedTriangle(const triangle& tri, const std::shared_ptr<const shader_base>& shader)
+  : boundedPrimitive(tri.boundingbox(), shader)
+{
+  _triangle = tri;
+}
+
+
+/////////////
+// Methods //
+/////////////
+intersectionPoint boundedTriangle::intersect(const ray& r) const
+{
+  // intersect triangle
+  float t;
+  vec3d bc;
+  bool hit = _triangle.intersect(r, bc, t);
+
+  // empty ip if not hit
+  if(!hit) return intersectionPoint();
+
+  // if hit, create intersectionPoint record.
+  else return intersectionPoint(r, t, _shader, 
+				_triangle.normal(bc),
+				_triangle.shadingAxis(),
+				_triangle.textureCoordinate(bc));
+}
+
+
+float boundedTriangle::area(void) const
+{
+  return _triangle.area();
+}
+
+
+surfaceSample boundedTriangle::sample(float r1, float r2) const
+{
+  float pdf;
+  vec3d bc, position = _triangle.sample(r1, r2, bc, pdf);
+  return surfaceSample(position, _triangle.normal(bc), pdf);
+}
+
+
+void boundedTriangle::_print(std::ostream& s) const
+{
+  s << "boundedTriangle (" << _bb << ", " << _triangle << ")";
+}
diff --git a/hw6/src/boundedVolumeNode.cpp b/hw6/src/boundedVolumeNode.cpp
new file mode 100644
index 0000000..fc790b5
--- /dev/null
+++ b/hw6/src/boundedVolumeNode.cpp
@@ -0,0 +1,97 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include <algorithm>
+
+#include "boundedVolumeNode.h"
+#include "random_number.h"
+
+boundedVolumeNode::boundedVolumeNode(const std::vector<std::shared_ptr<const boundedPrimitive>>::iterator& start, const std::vector<std::shared_ptr<const boundedPrimitive>>::iterator& end)
+
+  : _left(nullptr), _right(nullptr), boundedPrimitive()
+{
+  assert(std::distance(start, end) > 1);
+
+  // compute the bounding box
+  for_each(start, end, [&](const std::shared_ptr<const boundedPrimitive>& prim)
+  {
+    _bb += prim->boundingbox();
+  });
+
+  // select random splitting dimension & pivot
+  unsigned int split = random_int(2);
+  float pivot  = _bb.center()[split];
+
+  // partition
+  auto middle = std::partition(start, end, [&](const std::shared_ptr<const boundedPrimitive>& prim)
+  {
+    return prim->boundingbox().center()[split] < pivot;
+  });
+
+  // special case: all centers are the same.
+  if(start == middle) middle++;
+
+  // create _left (recurse if more than one primitive)
+  if(std::distance(start, middle) == 1)
+    _left = *start;
+  else 
+    _left = std::shared_ptr<const boundedPrimitive>(new boundedVolumeNode(start, middle));
+
+  // create _right (recurse if more than one primitive)
+  if(std::distance(middle, end) == 1)
+    _right = *middle;
+  else 
+    _right = std::shared_ptr<const boundedPrimitive>(new boundedVolumeNode(middle, end));
+
+  // Done.
+}
+
+intersectionPoint boundedVolumeNode::intersect(const ray& r) const
+{
+  intersectionPoint leftIp, rightIp;
+
+  // check left child
+  if(_left && _left->hitBoundingBox(r))
+    leftIp = _left->intersect(r);
+
+  // check right child
+  if(_right && _right->hitBoundingBox(r))
+    rightIp = _right->intersect(r);
+
+  // return closest
+  return std::min(leftIp, rightIp);
+}
+
+
+float boundedVolumeNode::area(void) const
+{
+  float total_area = 0.0f;
+  if(_left) total_area += _left->area();
+  if(_right) total_area += _right->area();
+  return total_area;
+}
+
+
+surfaceSample boundedVolumeNode::sample(float r1, float r2) const
+{
+  if(_left && !_right) return _left->sample(r1, r2);
+  else if(_right && !_left) return _right->sample(r1, r2);
+  else
+  {
+    float area_left = _left->area();
+    float area_right = _right->area();
+    float prob_left = area_left / (area_left + area_right);
+    float prob_right = 1.0f - prob_left;
+
+    if(r1 <= prob_left)
+      return _left->sample(r1 / prob_left, r2) * prob_left;
+    else
+      return _right->sample((r1 - prob_left) / prob_right, r2) * prob_right;
+  }
+}
diff --git a/hw6/src/boundingBox.cpp b/hw6/src/boundingBox.cpp
new file mode 100644
index 0000000..96b2261
--- /dev/null
+++ b/hw6/src/boundingBox.cpp
@@ -0,0 +1,195 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "interval.h"
+#include "constants.h"
+#include "boundingBox.h"
+
+
+/////////////////
+// Constructor //
+/////////////////
+boundingBox::boundingBox(void)
+{
+  // create an empty box (i.e., 'left' lies right of 'right')
+  _lfb = vec3d(+LARGE);
+  _rbt = vec3d(-LARGE);
+}
+
+
+boundingBox::boundingBox(const vec3d& lfb, const vec3d& rbt)
+{
+  _lfb = lfb;
+  _rbt = rbt;
+
+  // Make sure each component in _lfb is smaller than _rbt
+  for(unsigned int i=0; i < vec3d::size(); i++)
+    if(_rbt[i] < _lfb[i]) std::swap(_rbt[i], _lfb[i]);
+
+  // Done.
+}
+
+
+boundingBox::boundingBox(const boundingBox& bb)
+{
+  _lfb = bb._lfb;
+  _rbt = bb._rbt;
+}
+
+
+//////////////
+// Operator //
+//////////////
+boundingBox& boundingBox::operator=(const boundingBox& src)
+{
+  _assign(src);
+  return *this;
+}
+  
+
+boundingBox& boundingBox::operator+=(const boundingBox& bb)
+{
+  // compute the union of two bounding boxes
+  for(unsigned int i=0; i < vec3d::size(); i++)
+  {
+    if(_lfb[i] > bb._lfb[i]) _lfb[i] = bb._lfb[i];
+    if(_rbt[i] < bb._rbt[i]) _rbt[i] = bb._rbt[i];
+  }
+
+  return *this;
+}
+
+
+boundingBox boundingBox::operator+(const boundingBox& bb) const
+{
+  boundingBox result(*this);
+  result += bb;
+  return result;
+}
+
+
+boundingBox& boundingBox::operator+=(const vec3d& point)
+{
+  // expand the bounding box to include 'point' (+ a small epsilon)
+  for(unsigned int i=0; i < vec3d::size(); i++)
+  {
+    if(_lfb[i] > point[i]-EPSILON) _lfb[i] = point[i]-EPSILON;
+    if(_rbt[i] < point[i]+EPSILON) _rbt[i] = point[i]+EPSILON;
+  }
+
+  return *this;
+}
+
+
+/////////////
+// Methods //
+/////////////
+bool boundingBox::isHit(const ray& r) const
+{
+  // init
+  interval boxInterval(0, +LARGE);
+
+  // for every slab
+  for(unsigned int i=0; i != vec3d::size(); i++)
+  {
+    // compute the slab
+    interval slab(_lfb[i], _rbt[i]);
+    slab -= r.origin()[i];
+
+    // check for the case where the ray is parallel to the slab
+    if(fabs(r.direction()[i]) < EPSILON)
+    {
+      // if identical signs => no hit
+      if((slab.lower() < 0.0f) == (slab.upper() < 0.0f))
+	return false;
+
+      // skip remainder to this iteration
+      continue;
+    }
+    else
+      slab /= r.direction()[i];
+
+    // intersect
+    boxInterval.intersect(slab);
+    if(boxInterval.empty())
+      return false;
+  }
+
+  // Done.
+  return true;  
+}
+
+
+vec3d boundingBox::center(void) const
+{
+  return 0.5f * (_lfb + _rbt);
+}
+
+
+vec3d boundingBox::corner(bool left, bool front, bool bottom) const
+{
+  return vec3d( left ? _lfb.x : _rbt.x,
+		front ? _lfb.y : _rbt.y,
+		bottom ? _lfb.z : _rbt.z );
+}
+
+
+vec3d boundingBox::size(void) const
+{
+  vec3d s = (_rbt - _lfb);
+  if(s.x < 0 || s.y < 0 || s.z < 0) return vec3d();
+  else return s;
+}
+
+
+//////////////
+// Mutators //
+//////////////
+boundingBox& boundingBox::transform(const transformation3d& t)
+{
+  boundingBox result;
+  for(unsigned int i=0; i <= 1; i++)
+    for(unsigned int j=0; j <= 1; j++)
+      for(unsigned int k=0; k <= 1; k++)
+	result += t.transformPoint(corner(i,j,k));
+
+  // Done.
+  _swap(result);
+  return *this;
+}
+
+
+boundingBox& boundingBox::inverseTransform(const transformation3d& t)
+{
+  boundingBox result;
+  for(unsigned int i=0; i <= 1; i++)
+    for(unsigned int j=0; j <= 1; j++)
+      for(unsigned int k=0; k <= 1; k++)
+	result += t.inverseTransformPoint(corner(i,j,k));
+
+  // Done.
+  _swap(result);
+  return *this;
+}
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void boundingBox::_swap(boundingBox& bb)
+{
+  swap(_lfb, bb._lfb);
+  swap(_rbt, bb._rbt);
+}
+
+
+void boundingBox::_assign(const boundingBox& bb)
+{
+  _lfb = bb._lfb;
+  _rbt = bb._rbt;
+}
diff --git a/hw6/src/brdfSample.cpp b/hw6/src/brdfSample.cpp
new file mode 100644
index 0000000..90acfe4
--- /dev/null
+++ b/hw6/src/brdfSample.cpp
@@ -0,0 +1,116 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "brdfSample.h"
+
+//////////////////
+// Constructors //
+//////////////////
+brdfSample::brdfSample(void)
+{
+  _out = vec3d(0.0f, 0.0f, 1.0f);
+  _pdf = 0.0f;
+  _reflectance = color(0.0f);
+}
+
+brdfSample::brdfSample(const vec3d& out, const float pdf, const color& reflectance)
+{
+  _out = out;
+  _pdf = std::max(pdf, 0.0f);
+  _reflectance = reflectance;
+}
+
+
+brdfSample::brdfSample(const brdfSample& bs)
+{
+  _out = bs._out;
+  _pdf = bs._pdf;
+  _reflectance = bs._reflectance;
+}
+
+
+///////////////
+// Operators //
+///////////////
+brdfSample& brdfSample::operator=(const brdfSample& bs)
+{
+  _assign(bs);
+  return *this;
+}
+
+
+brdfSample brdfSample::operator*(float pdf) const
+{
+  return brdfSample(_out, _pdf * pdf, _reflectance);
+}
+
+
+brdfSample& brdfSample::operator*=(float pdf)
+{
+  _pdf *= pdf;
+  return *this;
+}
+  
+
+////////////////
+// Inspectors //
+////////////////
+const vec3d& brdfSample::exitantDirection(void) const
+{
+  return _out;
+}
+
+
+float brdfSample::pdf(void) const
+{
+  return _pdf;
+}
+
+
+const color& brdfSample::reflectance(void) const
+{
+  return _reflectance;
+}
+
+
+/////////////
+// Methods //
+/////////////
+brdfSample& brdfSample::transform(const transformation3d& t)
+{
+  _out = t.transformDirection(_out);
+  return *this;
+}
+
+
+brdfSample& brdfSample::inverseTransform(const transformation3d& t)
+{
+  _out = t.inverseTransformDirection(_out);
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void brdfSample::_swap(brdfSample& bs)
+{
+  swap(_out, bs._out);
+  std::swap(_pdf, bs._pdf);
+  swap(_reflectance, bs._reflectance);
+}
+
+
+void brdfSample::_assign(const brdfSample& bs)
+{
+  _out = bs._out;
+  _pdf = bs._pdf;
+  _reflectance = bs._reflectance;
+}
+
diff --git a/hw6/src/bumpMap.cpp b/hw6/src/bumpMap.cpp
new file mode 100644
index 0000000..ecd6f49
--- /dev/null
+++ b/hw6/src/bumpMap.cpp
@@ -0,0 +1,48 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include <algorithm>
+#include "bumpMap.h"
+#include "coordinateTransform.h"
+
+//////////////////
+// Constructors //
+//////////////////
+bumpMap::bumpMap(const std::shared_ptr<const texture_base>& map, float scale, unsigned int channel, const std::shared_ptr<const shader_base>& shader)
+  : shadingFrameTransformation(shader)
+{
+  _map = map;
+  _scale = scale;
+  _channel = std::max(channel, 2u);
+}
+
+/////////////
+// Methods //
+/////////////
+transformation3d bumpMap::_transformation(const vec2d& textureCoord) const
+{
+  // get derivative in X and Y direction
+  assert(_map);
+  float dx = (*_map)(textureCoord)[_channel] - (*_map)(textureCoord + vec2d(1.0f/_map->width(), 0.0f))[_channel];
+  float dy = (*_map)(textureCoord)[_channel] - (*_map)(textureCoord + vec2d(0.0f, 1.0f/_map->height()))[_channel];
+
+  // get desired local normal = (1.0, 0.0, dx) cross (0.0, 1.0, dy)
+  vec3d normal(-dx, -dy, 1.0f / _scale);
+  normal.normalize();
+
+  // create coordinate system. Keep U aligned as close as possible to the X axis.
+  return coordinateTransformation(normal, vec3d(1.0f, 0.0, 0.0));
+}
+
+
+void bumpMap::_print(std::ostream& s) const
+{
+  s << "bumpMap (" << _scale << " x " << *_map << "[" << _channel << "]) -> {" << *_shader << "}";
+}
+
diff --git a/hw6/src/bvh_intersector.cpp b/hw6/src/bvh_intersector.cpp
new file mode 100644
index 0000000..2eedb2f
--- /dev/null
+++ b/hw6/src/bvh_intersector.cpp
@@ -0,0 +1,54 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "bvh_intersector.h"
+#include "boundedVolumeNode.h"
+
+//////////////////
+// Constructors //
+//////////////////
+bvh_intersector::bvh_intersector(void)
+  : intersector_base()
+{
+  // Do nothing
+}
+
+
+bvh_intersector::bvh_intersector(const std::vector<std::shared_ptr<const boundedPrimitive>>& compounds)
+  : intersector_base()
+{
+  // quick bail out if no compounds provided
+  if(compounds.empty()) return; 
+
+  // make a copy
+  std::vector<std::shared_ptr<const boundedPrimitive>> compoundCopy = compounds;
+
+  // create node
+  //   trivial case: only a single node
+  if(compounds.size() == 1)
+    _root = compounds[0];
+  //   compound case: create a bvh
+  else
+    _root = std::shared_ptr<const boundedPrimitive>(new boundedVolumeNode(compoundCopy.begin(), compoundCopy.end()));
+}
+
+  
+/////////////
+// Methods //
+/////////////
+intersectionPoint bvh_intersector::intersect(const ray& r) const
+{
+  // check if BVH exists => empty intersection point if not.
+  if(!_root) return intersectionPoint();
+
+  // intersect
+  return _root->intersect(r);
+}
+
+
+
diff --git a/hw6/src/camera.cpp b/hw6/src/camera.cpp
new file mode 100644
index 0000000..3393dc9
--- /dev/null
+++ b/hw6/src/camera.cpp
@@ -0,0 +1,150 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include <cmath>
+
+#include "constants.h"
+#include "camera.h"
+
+/////////////////
+// Constructor //
+/////////////////
+camera::camera(void)
+{
+  _eye = vec3d();
+  _view = vec3d(0.0f, 0.0f, -1.0f);
+  _up = vec3d(0.0f, 1.0f, 0.0f);
+  _fov = 60.0f;
+  _width = _height = 256;
+}
+
+
+camera::camera(const vec3d& eye, const vec3d& viewDirection, const vec3d& up, float fov, size_t xres, size_t yres)
+{
+  _eye = eye;
+  _view = normalize(viewDirection);
+  _up = normalize(up);
+  _fov = fov;
+  _width = xres;
+  _height = yres;
+
+  // fix up if needed
+  vec3d right = _view.cross(up).normalize();
+  _up = right.cross(_view).normalize();
+}
+
+
+camera::camera(const camera& cam)
+{
+  _eye = cam._eye;
+  _view = cam._view;
+  _up = cam._up;
+  _fov = cam._fov;
+  _width = cam._width;
+  _height = cam._height;
+}
+
+
+///////////////
+// Operators //
+///////////////
+camera& camera::operator=(const camera& cam)
+{
+  _assign(cam);
+  return *this;
+}
+
+
+ray camera::operator()(float x, float y) const
+{
+  vec3d right = _view.cross(_up).normalize();
+
+  // aspect ratio
+  float aspect = (float)(_height) / (float)(_width);
+  float tanFov = tan(_fov / 180.0f * PI);
+
+  // compute view plane center, and U and V unnormalized axes.
+  vec3d center = _eye + _view;
+  vec3d U = 2.0f * tanFov * right;
+  vec3d V = -2.0f * tanFov * aspect * _up;  // y runs from top to bottom (opposite direction of up)
+
+  // get point on view plane
+  vec3d p = center + (x / (float)(_width) - 0.5f) * U + (y / (float)(_height) - 0.5f) * V;
+
+  // Done.
+  return ray(_eye, p - _eye);
+}
+
+
+//////////////
+// Mutators //
+//////////////
+void camera::frameBoundingBox(const boundingBox& bb)
+{
+  // determine the best eye location, given the other parameters and a bounding box such that the bounding box maximally occupies the view
+  vec3d right = _view.cross(_up).normalize();
+  _eye = 0.5f * (bb.corner(true,true,true) + bb.corner(false,false,false));
+
+  // => find max projection in up and right direction.
+  float maxRight=-LARGE, maxUp=-LARGE, maxDepth=-LARGE;
+  for(unsigned int i=0; i < 8; i++)
+  {
+    vec3d c = bb.corner( (i&1)==1, (i&2)==2, (i&4)==4 ) - _eye;
+    
+    float r = fabs(c.dot(right));
+    float u = fabs(c.dot(_up));
+    float d = fabs(c.dot(_view));
+
+    maxRight = std::max(maxRight, r);
+    maxUp = std::max(maxUp, u);
+    maxDepth = std::max(maxDepth, d);
+  }
+
+  // => compute optimal distance for up and right
+  float aspect = (float)(_height) / (float)(_width);
+  float tanFov = tan(_fov / 180.0f * PI);
+  float optDistUp = fabs(maxUp / tanFov);
+  float optDistRight = fabs(maxRight / (tanFov * aspect));
+  
+  // => move _eye back based on (max) optimal distance
+  _eye -= _view * (std::max(optDistUp, optDistRight) + maxDepth);
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void camera::_swap(camera& cam)
+{
+  // sanity check
+  if(&cam == this) return;
+
+  // swap
+  swap(_eye, cam._eye);
+  swap(_view, cam._view);
+  swap(_up, cam._up);
+  std::swap(_fov, cam._fov);
+  std::swap(_width, cam._width);
+  std::swap(_height, cam._height);
+}
+
+
+void camera::_assign(const camera& cam)
+{
+  // sanity check
+  if(&cam == this) return;
+
+  // copy
+  _eye = cam._eye;
+  _view = cam._view;
+  _up = cam._up;
+  _fov = cam._fov;
+  _width = cam._width;
+  _height = cam._height;
+}
diff --git a/hw6/src/color.cpp b/hw6/src/color.cpp
new file mode 100644
index 0000000..b2b720f
--- /dev/null
+++ b/hw6/src/color.cpp
@@ -0,0 +1,233 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include <cassert>
+#include <algorithm>
+#include "color.h"
+
+//////////////////
+// Constructors //
+//////////////////
+color::color(color::const_reference value)
+{ 
+  r = g = b = value;
+}
+
+
+color::color(color::const_reference r, color::const_reference g, color::const_reference b) 
+{
+  this->r = r;
+  this->g = g;
+  this->b = b;
+}
+
+
+color::color(const color& col)
+{
+  r = col.r;
+  g = col.g;
+  b = col.b;
+}
+ 
+
+////////////////
+// Inspectors //
+////////////////
+color::const_reference color::operator[](size_t index) const 
+{ 
+  assert(index < size());
+  return data[index]; 
+}
+
+
+color::reference color::operator[](size_t index) 
+{ 
+  assert(index < size());
+  return data[index]; 
+}
+
+
+color::iterator color::begin(void)
+{
+  return data;
+}
+
+
+color::const_iterator color::begin(void) const
+{
+  return data;
+}
+
+
+color::iterator color::end(void) 
+{
+  return begin() + size();
+}
+
+
+color::const_iterator color::end(void) const
+{
+  return begin() + size();
+}
+
+
+///////////////
+// Operators //
+///////////////
+color& color::operator=(const color& col) 
+{ 
+  _assign(col); 
+  return *this; 
+}
+
+
+bool color::operator==(const color& col) const 
+{ 
+  return (r == col.r) && (g == col.g) && (b == col.b); 
+}
+
+
+bool color::operator!=(const color& col) const 
+{ 
+  return (r != col.r) || (g != col.g) || (b != col.b); 
+}
+  
+
+color color::operator+(const color& col) const 
+{ 
+  return color(r + col.r, g + col.g, b + col.b); 
+}
+
+
+color color::operator-(const color& col) const 
+{ 
+  return color(r - col.r, g - col.g, b - col.b); 
+}
+
+
+color color::operator*(const color& col) const 
+{ 
+  return color(r * col.r, g * col.g, b * col.b); 
+}
+
+
+color color::operator*(color::const_reference scale) const 
+{ 
+  return color(r * scale, g * scale, b * scale); 
+}
+
+
+color color::operator/(const color& col) const 
+{ 
+  return color(r / col.r, g / col.g, b / col.b); 
+}
+
+
+color color::operator/(color::const_reference scale) const 
+{ 
+  return color(r / scale, g / scale, b / scale); 
+}
+
+
+color& color::operator+=(const color& col) 
+{ 
+  r += col.r; 
+  g += col.g; 
+  b += col.b; 
+  return *this; 
+}
+
+
+color& color::operator-=(const color& col) 
+{ 
+  r -= col.r; 
+  g -= col.g; 
+  b -= col.b; 
+  return *this; 
+}
+
+
+color& color::operator*=(const color& col) 
+{ 
+  r *= col.r; 
+  g *= col.g;
+  b *= col.b;  
+  return *this; 
+}
+
+
+color& color::operator*=(color::const_reference scale) 
+{ 
+  r *= scale; 
+  g *= scale; 
+  b *= scale; 
+  return *this; 
+}
+
+
+color& color::operator/=(const color& col) 
+{ 
+  r /= col.r; 
+  g /= col.g; 
+  b /= col.b; 
+  return *this; 
+}							
+
+
+color& color::operator/=(color::const_reference scale) 
+{ 
+  r /= scale; 
+  g /= scale; 
+  b /= scale; 
+  return *this; 
+}
+
+
+
+///////////////
+// Modifiers //
+///////////////
+color& color::abs(void)
+{
+  std::for_each(begin(), end(), [](reference val) 
+  { 
+    if(val<0) val = -val;
+  });
+  return *this;
+}
+
+
+color& color::clamp(const_reference lowerBound, const_reference upperBound)
+{
+  std::for_each(begin(), end(), [&](reference val) 
+  { 
+    if(val < lowerBound) val = lowerBound;
+    else if(val > upperBound) val = upperBound; 
+  });
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void color::_assign(const color& col)
+{ 
+  r = col.r;  
+  g = col.g; 
+  b = col.b; 
+}
+
+
+void color::_swap(color& col) 
+{
+  std::swap(r, col.r);
+  std::swap(g, col.g);
+  std::swap(b, col.b);
+}
diff --git a/hw6/src/compoundShader.cpp b/hw6/src/compoundShader.cpp
new file mode 100644
index 0000000..6456fdc
--- /dev/null
+++ b/hw6/src/compoundShader.cpp
@@ -0,0 +1,141 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include <algorithm>
+#include "compoundShader.h"
+#include "random_number.h"
+#include <iostream> // DEBUG
+
+//////////////////
+// Constructors //
+//////////////////
+compoundShader::compoundShader(const std::vector<std::shared_ptr<const shader_base>>& shader_list)
+  : shader_base()
+{
+  _compound = shader_list;
+}
+
+
+/////////////
+// Methods //
+/////////////
+color compoundShader::shade(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  color result(0.0f, 0.0f, 0.0f);
+  for_each(_compound.begin(), _compound.end(), [&](const std::shared_ptr<const shader_base>& shader)
+  {
+    result += shader->shade(ip, light_dir);
+  });
+
+  // Done.
+  return result;
+}
+
+
+color compoundShader::reflectance(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  color result(0.0f, 0.0f, 0.0f);
+  for_each(_compound.begin(), _compound.end(), [&](const std::shared_ptr<const shader_base>& shader)
+  {
+    result += shader->reflectance(ip, light_dir);
+  });
+
+  // Done.
+  return result;
+}
+
+
+brdfSample compoundShader::sample(const intersectionPoint& ip, float r1, float r2) const
+{
+  // santiy check
+  if(_compound.empty()) return brdfSample();
+
+  // initialize
+  auto currentCompound = _compound.begin();
+  float pdf = 1.0f;
+
+  // HW6: implement importance sampling of BRDF, where you select
+  //      a BRDF propertional to their relative reflectivity.
+  //      For example, if the compound shader has two BRDFs with
+  //      an reflectivity of 20% and 40%, then the likelihood that
+  //      the second BRDF is sampled is twice that of the first BRDF.
+  //      Practically, you need to point the 'currentCompound' to the BRDF
+  //      you want sample, and set 'pdf' to the PDF of the selection.
+  // Modifies: nothing
+  // Returns: brdfSample
+
+  float cdf = 0.0f;
+  float choice = random_float(1.0f) * reflectivity(ip);
+
+  // compute cdf until it exceeds choice probability and select that compound
+  while (currentCompound < _compound.end() && choice >= cdf) {
+    pdf = (**currentCompound).reflectivity(ip);
+    cdf += pdf;
+    currentCompound++;
+  }
+
+  // move currentCompound back to selection
+  currentCompound--;
+
+  // generate sample (do not remove -- this line will produce the correct
+  //  result if currentCompound and pdf are set correctly).
+  return (*currentCompound)->sample(ip, r1, r2) * pdf;
+}
+
+
+float compoundShader::reflectivity(const intersectionPoint& ip) const
+{
+  // return sum of reflectivity
+  float total_reflectivity = 0.0f;
+  for_each(_compound.begin(), _compound.end(), [&](const std::shared_ptr<const shader_base>& shader)
+  {
+    total_reflectivity += shader->reflectivity(ip);
+  });
+
+  // Done.
+  return total_reflectivity;
+}
+
+
+color compoundShader::emittance(const intersectionPoint& ip) const
+{
+  // return total sum of emittance
+  color total_emittance;
+  for_each(_compound.begin(), _compound.end(), [&](const std::shared_ptr<const shader_base>& shader)
+  {
+    total_emittance += shader->emittance(ip);
+  });
+
+  // Done.
+  return total_emittance;
+}
+
+
+shaderProperties compoundShader::properties(const intersectionPoint& ip) const
+{
+  // if any component has a property set, then set it for the compound
+  shaderProperties result(false, false);
+  for(unsigned int i=0; i < _compound.size(); i++)
+    result |= _compound[i]->properties(ip);
+
+  // Done.
+  return result;
+}
+
+
+void compoundShader::_print(std::ostream& s) const
+{
+  s << "Compound Shader (" << _compound.size() << " components): {";
+  for(unsigned int i=0; i < _compound.size(); i++)
+  {
+    s << *_compound[i];
+    if(i != _compound.size()-1) s << ", ";
+  }
+  s << "}";
+}
diff --git a/hw6/src/coordinateTransform.cpp b/hw6/src/coordinateTransform.cpp
new file mode 100644
index 0000000..29e19f4
--- /dev/null
+++ b/hw6/src/coordinateTransform.cpp
@@ -0,0 +1,67 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "coordinateTransform.h"
+
+//////////////////
+// Constructors //
+//////////////////
+coordinateTransformation::coordinateTransformation(void)
+{
+  // do nothing
+}
+
+
+coordinateTransformation::coordinateTransformation(const vec3d& normal)
+{
+  // normal == Z axis
+  vec3d X, Y, Z = normalize(normal);
+  
+  // select Y axis
+  if(fabs(Z.x) < fabs(Z.y) && fabs(Z.x) < fabs(Z.z))
+    Y = normalize(vec3d(0.0f, Z.z, -Z.y));
+  else if(fabs(Z.y) < fabs(Z.z))
+    Y = normalize(vec3d(Z.z, 0.0f, -Z.x));
+  else
+    Y = normalize(vec3d(Z.y, -Z.x, 0.0f));
+  
+  // create other axis
+  X = Y.cross(Z).normalize();
+
+  // copy
+  _transformation = mat3d(X, Y, Z);
+  _inverseTransformation = transpose(_transformation);
+
+  // Done.
+}
+
+
+coordinateTransformation::coordinateTransformation(const vec3d& normal, const vec3d& axis)
+{
+  // normal == Z axis
+  vec3d Z = normalize(normal);
+  
+  // create other axis
+  vec3d axis_normalized = normalize(axis);
+  vec3d Y = Z.cross(axis_normalized).normalize();
+  vec3d X = Y.cross(Z).normalize();
+
+  // copy
+  _transformation = mat3d(X, Y, Z);
+  _inverseTransformation = transpose(_transformation);
+
+  // Done.
+}
+
+
+coordinateTransformation::coordinateTransformation(const vec3d& X, const vec3d& Y, const vec3d& Z)
+{
+  // trust user to provide an orthogonal set of vectors.
+  _transformation = mat3d(X, Y, Z);
+  _inverseTransformation = transpose(_transformation);
+}
diff --git a/hw6/src/diffuseBrdf.cpp b/hw6/src/diffuseBrdf.cpp
new file mode 100644
index 0000000..2256f73
--- /dev/null
+++ b/hw6/src/diffuseBrdf.cpp
@@ -0,0 +1,111 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "constants.h"
+#include "diffuseBrdf.h"
+
+//////////////////
+// Constructors //
+//////////////////
+diffuseBrdf::diffuseBrdf(const color& albedo)
+{
+  _albedo = albedo;
+}
+
+
+diffuseBrdf::diffuseBrdf(const diffuseBrdf& src)
+{
+  _albedo = src._albedo;
+}
+
+
+///////////////
+// Operators //
+///////////////
+diffuseBrdf& diffuseBrdf::operator=(const diffuseBrdf& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+/////////////
+// Methods //
+/////////////
+color diffuseBrdf::shade(const vec3d& in, const vec3d& out) const
+{
+  if(in.z < 0.0f || out.z < 0.0f) return color();
+  else return _albedo * in.z;
+}
+
+
+color diffuseBrdf::reflectance(const vec3d& in, const vec3d& out) const
+{
+  if(in.z < 0.0f || out.z < 0.0f) return color(0.0f);
+  return _albedo / PI;
+}
+
+
+brdfSample diffuseBrdf::sample(const vec3d& in, float r1, float r2) const
+{
+  // check if below surface.
+  if(in.z < EPSILON) return brdfSample();
+
+  // sample hemisphere proportional to the cosine
+  vec3d out( cos(2.0f * PI * r1) * sqrt(std::max(1.0f - r2, 0.0f)),
+	     sin(2.0f * PI * r1) * sqrt(std::max(1.0f - r2, 0.0f)),
+	     sqrt(r2) );
+
+  // set pdf
+  float pdf = out.z / PI;
+
+  // Done.
+  return brdfSample(out, 
+		    out.z / PI,                     // PDF proportional to cosine
+		    _albedo / PI                    // reflectance
+		    );
+}
+
+
+bool diffuseBrdf::isSpecular(void) const
+{
+  return false;
+}
+
+
+bool diffuseBrdf::isDiffuse(void) const
+{
+  return true;
+}
+
+
+float diffuseBrdf::reflectivity(void) const
+{
+  return (_albedo.r + _albedo.g + _albedo.b) / 3.0f;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void diffuseBrdf::_assign(const diffuseBrdf& src)
+{
+  _albedo = src._albedo;
+}
+
+
+void diffuseBrdf::_swap(diffuseBrdf& src)
+{
+  swap(_albedo, src._albedo);
+}
+
+void diffuseBrdf::_print(std::ostream& s) const
+{
+  s << "Diffuse BRDF: albedo=" << _albedo;
+}
diff --git a/hw6/src/diffuseReflectanceShader.cpp b/hw6/src/diffuseReflectanceShader.cpp
new file mode 100644
index 0000000..4d2d2a4
--- /dev/null
+++ b/hw6/src/diffuseReflectanceShader.cpp
@@ -0,0 +1,35 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "diffuseReflectanceShader.h"
+
+
+/////////////////
+// Constructor //
+/////////////////
+diffuseReflectanceShader::diffuseReflectanceShader(const colorReflectanceParameter& albedo)
+  : reflectanceShader_base()
+{
+  _albedo = albedo;
+}
+
+
+///////////////////////
+// Protected Methods //
+///////////////////////
+std::unique_ptr<const brdf_base> diffuseReflectanceShader::make_brdf(const vec2d& textureCoord) const
+{
+  return std::unique_ptr<const brdf_base>(new diffuseBrdf( _albedo(textureCoord) ));
+}
+
+
+void diffuseReflectanceShader::_print(std::ostream& s) const
+{
+  s << "Diffuse Reflectance: albedo=" << _albedo;
+}
diff --git a/hw6/src/directionalLightsource.cpp b/hw6/src/directionalLightsource.cpp
new file mode 100644
index 0000000..7703eb1
--- /dev/null
+++ b/hw6/src/directionalLightsource.cpp
@@ -0,0 +1,47 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "constants.h"
+#include "directionalLightsource.h"
+
+//////////////////
+// Constructors //
+//////////////////
+directionalLightsource::directionalLightsource(const vec3d& direction, const color& power)
+{
+  _direction = normalize(direction);
+  _power = power;
+}
+
+
+/////////////
+// Methods //
+/////////////
+lightSample directionalLightsource::intensityAt(const vec3d& point) const
+{
+  return lightSample(_direction, _power, +LARGE);
+}
+
+
+lightSample directionalLightsource::emittanceAt(const vec3d& point, float r1, float r2) const
+{
+  // Set emittance to _power * distance^2 to compensate for squared distance fall off.
+  // Distance is set to large (to ensure everything can occlude).
+  // Foreshortening == 1
+  // PDF == 1 (no selection).
+  return lightSample(_direction, _power * LARGE * LARGE, LARGE, 1.0f, 1.0f);
+}
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void directionalLightsource::_print(std::ostream& s) const
+{
+  s << "Directional Lightsource: direction=" << _direction << ", power=" << _power;  
+}
diff --git a/hw6/src/environmentMap.cpp b/hw6/src/environmentMap.cpp
new file mode 100644
index 0000000..896d78e
--- /dev/null
+++ b/hw6/src/environmentMap.cpp
@@ -0,0 +1,79 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "constants.h"
+#include "environmentMap.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+environmentMap::environmentMap(const std::shared_ptr<const texture_base>& map, const transformation3d& transform)
+{
+  _map = map;
+  _transform = transform;
+}
+
+
+environmentMap::environmentMap(const environmentMap& src)
+{
+  _map = src._map;
+  _transform = src._transform;
+}
+
+
+///////////////
+// Operators //
+///////////////
+environmentMap environmentMap::operator=(const environmentMap& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+color environmentMap::operator()(const vec3d& direction) const
+{
+  // normalize & apply transformation
+  vec3d dir = _transform.inverseTransformDirection(normalize(direction));
+
+  // compute spherical coordinates
+  float theta = acos(dir.z);
+  float phi = atan2(dir.y, dir.x);
+
+  if(phi < 0.0f) phi += 2.0f * PI;
+
+  // get texel
+  return _map->operator()(vec2d(0.5f * phi / PI, theta / PI));
+}
+
+
+///////////////////////
+// Protected Methods //
+///////////////////////
+void environmentMap::_assign(const environmentMap& src)
+{
+  if(&src == this) return;
+  
+  _map = src._map;
+  _transform = src._transform;
+}
+
+
+void environmentMap::_swap(environmentMap& swp)
+{
+  std::swap(_map, swp._map);
+  swap(_transform, swp._transform);
+}
+
+
+void environmentMap::_print(std::ostream& s) const
+{
+  s << "Environment Map (" << *_map << ", " << _transform << ")";
+}
diff --git a/hw6/src/errorMessage.cpp b/hw6/src/errorMessage.cpp
new file mode 100644
index 0000000..3eddb6a
--- /dev/null
+++ b/hw6/src/errorMessage.cpp
@@ -0,0 +1,34 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "errorMessage.h"
+
+#include <cstdio>
+#include <cstdlib>
+
+void errorMessage(const char* msg, ...)
+{
+  printf("ERROR: ");
+  va_list args;
+  va_start(args, msg);
+  vprintf(msg, args);
+  va_end(args);
+  printf("\r\n");
+  exit(-1);
+}
+
+
+void warningMessage(const char* msg, ...)
+{
+  printf("WARNING: ");
+  va_list args;
+  va_start(args, msg);
+  vprintf(msg, args);
+  va_end(args);
+  printf("\r\n");
+}
diff --git a/hw6/src/image.cpp b/hw6/src/image.cpp
new file mode 100644
index 0000000..59434cc
--- /dev/null
+++ b/hw6/src/image.cpp
@@ -0,0 +1,122 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "image.h"
+
+#include <algorithm>
+#include <cassert>
+
+//////////////////
+// Constructors //
+//////////////////
+image::image(image::size_type width, image::size_type height) : _width(width), _height(height), _data()
+{
+  if(width != 0 && height != 0)
+    _data.reset(new value_type[width*height]);
+}
+
+
+image::image(image::size_type width, image::size_type height, const_reference col) : image(width, height)
+{
+  std::fill(begin(), end(), col);
+}
+
+
+image::image(const image& src) : image(src.width(), src.height())
+{
+  std::copy(src.begin(), src.end(), begin());
+}
+
+
+image::image(image&& src)
+{
+  _swap(src);
+}
+
+
+////////////////
+// Inspectors //
+////////////////
+image::iterator image::begin(void)
+{
+  return _data.get();
+}
+
+
+image::const_iterator image::begin(void) const
+{
+  return _data.get();
+}
+
+
+image::iterator image::end(void)
+{
+  return begin() + size();
+}
+
+
+image::const_iterator image::end(void) const
+{
+  return begin() + size();
+}
+
+
+///////////////
+// Operators //
+///////////////
+image& image::operator=(const image& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+image& image::operator=(image&& src)
+{
+  _swap(src);
+  return *this;
+}
+
+image::reference image::operator()(image::size_type x, image::size_type y)
+{
+  assert(x >= 0 && x < width());
+  assert(y >= 0 && y < height());
+  return begin()[y*width() + x];
+}
+
+
+image::const_reference image::operator()(image::size_type x, image::size_type y) const
+{
+  assert(x >= 0 && x < width());
+  assert(y >= 0 && y < height());
+  return begin()[y*width() + x];
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void image::_swap(image& img)
+{
+  std::swap(_width, img._width);
+  std::swap(_height, img._height);
+  std::swap(_data, img._data);
+}
+
+
+void image::_assign(const image& src)
+{
+  // sanity check
+  if(&src == this) return;
+
+  // make copy
+  image temp(src);
+  _swap(temp);
+
+  // Done
+}
diff --git a/hw6/src/imageIO.cpp b/hw6/src/imageIO.cpp
new file mode 100644
index 0000000..cee716b
--- /dev/null
+++ b/hw6/src/imageIO.cpp
@@ -0,0 +1,46 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "util.h"
+#include "imageIO.h"
+#include "imageIO.ppm.h"
+#include "imageIO.pfm.h"
+#include "errorMessage.h"
+
+
+////////////
+// Import //
+////////////
+void importImage(const std::string& name, image& img)
+{
+  // get extension
+  std::string ext = getExtension(name);
+  if(ext == "") errorMessage("Unable to determine extension in '%s'.", name.c_str());
+
+  // call image format handler based on extension
+  if(ext == "PPM" || ext == "ppm") importPPM(name, img);
+  else if(ext == "PFM" || ext == "pfm") importPFM(name, img);
+  else errorMessage("Unknown image format: '%s'.", ext.c_str());
+}
+
+
+////////////
+// Export //
+////////////
+void exportImage(const std::string& name, const image& img)
+{
+  // get extension
+  std::string ext = getExtension(name);
+  if(ext == "") errorMessage("Unable to determine extension in '%s'.", name.c_str());
+
+  // call image format handler based on extension
+  if(ext == "PPM" || ext == "ppm") exportPPM(name, img);
+  else if(ext == "PFM" || ext == "pfm") exportPFM(name, img);
+  else errorMessage("Unknown image format: '%s'.", ext.c_str());
+}
+
diff --git a/hw6/src/imageIO.pfm.cpp b/hw6/src/imageIO.pfm.cpp
new file mode 100644
index 0000000..30d1c23
--- /dev/null
+++ b/hw6/src/imageIO.pfm.cpp
@@ -0,0 +1,88 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "imageIO.pfm.h"
+#include "errorMessage.h"
+
+#include <memory>
+#include <cassert>
+#include <fstream>
+
+
+//////////////////////
+// Helper functions //
+//////////////////////
+static void skipToNewline(std::ifstream& ifs)
+{
+  while(ifs.get() != '\n' && ifs.good()); 
+}
+
+static void skipComments(std::ifstream& ifs)
+{
+  while(!ifs.eof() && ifs.peek() == '#') skipToNewline(ifs); 
+}
+
+
+////////////////
+// Import PFM //
+////////////////
+void importPFM(const std::string& name, image& img)
+{
+  // open file
+  std::ifstream ifs(name.c_str(), std::ifstream::binary);
+  if(!ifs.is_open()) errorMessage("Unable to open file: '%s'.", name.c_str());
+
+  // read header
+  std::string magicMark;
+  ifs >> magicMark;
+  skipToNewline(ifs);
+  if(magicMark != "PF") errorMessage("Unsupported PFM format (%s).", magicMark.c_str());
+
+  // read width and height
+  image::size_type width, height;
+  skipComments(ifs);
+  ifs >> width >> height;
+  skipToNewline(ifs);
+
+  // allocate
+  img = image(width, height);
+
+  // check magic number (again)
+  skipComments(ifs);
+  ifs >> magicMark;
+  skipToNewline(ifs);
+  if(magicMark != "-1.000000") errorMessage("Unsupported byte-order in PFM.");
+
+  // read directly in float image
+  ifs.read((char *)(img.begin()), img.size() * sizeof(color));
+
+  // Done.
+}
+
+
+////////////////
+// Export PFM //
+////////////////
+void exportPFM(const std::string& name, const image& img)
+{
+  // sanity check
+  assert(img.width() != 0 && img.height() != 0);
+
+  // open file
+  std::ofstream ofs(name.c_str(), std::ofstream::binary);
+  if(!ofs.is_open()) errorMessage("Unable to open file: '%s'.", name.c_str());
+
+  // write header
+  ofs << "PF\n" << img.width() << " " << img.height() << "\n-1.000000\n";
+
+  // write float buffer
+  ofs.write((const char*)(img.begin()), img.size() * sizeof(color));
+
+  // Done.
+}
+
diff --git a/hw6/src/imageIO.ppm.cpp b/hw6/src/imageIO.ppm.cpp
new file mode 100644
index 0000000..00b3eee
--- /dev/null
+++ b/hw6/src/imageIO.ppm.cpp
@@ -0,0 +1,106 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "imageIO.ppm.h"
+#include "errorMessage.h"
+
+#include <memory>
+#include <cassert>
+#include <cstdint>
+#include <fstream>
+#include <algorithm>
+
+//////////////////////
+// Helper functions //
+//////////////////////
+static void skipToNewline(std::ifstream& ifs)
+{
+  while(ifs.get() != '\n' && ifs.good()); 
+}
+
+static void skipComments(std::ifstream& ifs)
+{
+  while(!ifs.eof() && ifs.peek() == '#') skipToNewline(ifs); 
+}
+
+
+////////////////
+// Import PPM //
+////////////////
+void importPPM(const std::string& name, image& img)
+{
+  // open file
+  std::ifstream ifs(name.c_str(), std::ifstream::binary);
+  if(!ifs.is_open()) errorMessage("Unable to open file: '%s'.", name.c_str());
+
+  // read header
+  std::string magicMark;
+  ifs >> magicMark;
+  skipToNewline(ifs);
+  if(magicMark != "P6") errorMessage("Unsupported PPM format (%s).", magicMark.c_str());
+
+  // read width & height
+  image::size_type width, height;
+  skipComments(ifs);
+  ifs >> width >> height;
+  skipToNewline(ifs);
+
+  // allocate
+  img = image(width, height);
+
+  // check magic number (again)
+  skipComments(ifs);
+  ifs >> magicMark;
+  skipToNewline(ifs);
+  if(magicMark != "255") errorMessage("Unsupported bit-depth in PPM file (%s).", magicMark.c_str());
+
+  // read char buffer
+  std::unique_ptr<uint8_t[]> tempBuffer(new uint8_t[img.size() * 3]);
+  ifs.read((char *)(tempBuffer.get()), img.size() * 3);
+
+  // convert to image
+  std::transform(tempBuffer.get(), tempBuffer.get() + (img.size()*3), img.begin()->begin(), [](uint8_t val) 
+  { 
+    return (float)(val) / 255.0f; 
+  });
+
+  // Done.
+}
+
+
+////////////////
+// Export PPM //
+////////////////
+void exportPPM(const std::string& name, const image& img)
+{
+  // sanity check
+  assert(img.width() != 0 && img.height() != 0);
+
+  // open file
+  std::ofstream ofs(name.c_str(), std::ofstream::binary);
+  if(!ofs.is_open()) errorMessage("Unable to open file: '%s'.", name.c_str());
+
+  // write header
+  ofs << "P6\n" << img.width() << " " << img.height() << "\n" << "255\n";
+
+  // convert to char buffer
+  std::unique_ptr<uint8_t[]> tempBuffer(new uint8_t[img.size() * 3]);
+  std::transform(img.begin()->begin(), img.end()->begin(), tempBuffer.get(), [](float val)
+  { 
+    return (val < 0.0f) ? 0 : 
+           (val > 1.0f) ? 255 : 
+           uint8_t(val*255); 
+   });
+    
+  // write body
+  ofs.write((const char*)(tempBuffer.get()), img.size() * 3);
+
+  // Done.
+}
+
+
diff --git a/hw6/src/importOBJ.cpp b/hw6/src/importOBJ.cpp
new file mode 100644
index 0000000..53354be
--- /dev/null
+++ b/hw6/src/importOBJ.cpp
@@ -0,0 +1,152 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include <memory>
+#include <string>
+#include <cassert>
+#include <fstream>
+
+#include "vec3d.h"
+#include "vec2d.h"
+#include "importOBJ.h"
+#include "errorMessage.h"
+
+void skipLine(std::ifstream& ifs)
+{
+  unsigned char c = ifs.get();
+  while(ifs.good() && c != '\r' && c != '\n') c = ifs.get();
+  while(ifs.good() && (c == '\r' || c == '\n')) c = ifs.get();
+  ifs.unget();
+}
+
+void importOBJ(const std::string filename, std::vector<triangle>& triangle_list)
+{
+  // define buffers
+  auto vertex_list = std::make_shared<std::vector<vec3d>>();
+  auto normal_list = std::make_shared<std::vector<vec3d>>();
+  auto textureCoord_list = std::make_shared<std::vector<vec2d>>();
+
+  // open obj file
+  std::ifstream ifs(filename, std::ifstream::in | std::ifstream::binary);
+  if(!ifs.is_open()) 
+    errorMessage("Unable to import OBJ (%s).", filename.c_str());
+
+  // read line by line
+  unsigned char key;
+  while(ifs.good())
+  {
+    // get key
+    key = ifs.get();
+
+    // VERTEX DATA:
+    if(key == 'v')
+    {
+      // get vertex data
+      key = ifs.get();
+
+      // Vertex Coordinate
+      if(key == ' ') 
+      {
+	vec3d v;
+	ifs >> v.x >> v.y >> v.z;
+	vertex_list->push_back(v);
+      }
+
+      // Texture Coordinate
+      else if(key == 't')
+      {
+	vec2d t;
+	ifs >> t.u >> t.v;
+	textureCoord_list->push_back(t);
+      }
+
+      // Normal
+      else if(key == 'n')  
+      {
+	vec3d n;
+	ifs >> n.x >> n.y >> n.z;
+	normal_list->push_back(n);
+      }
+
+      // Unknown => ERROR
+      else errorMessage("Unknown OBJ vertex-key: v%c.", key);
+    }
+
+    // POLYGON:
+    else if(key == 'f')
+    {
+      // temp data structures 
+      std::vector<unsigned int> vidx;
+      std::vector<unsigned int> nidx;
+      std::vector<unsigned int> tidx;
+
+      // get polygon data
+      // can be either: 
+      // 1)  v0 v1 .. vn
+      // 2)  v0//n0 v1//n1 .. vn//nn
+      // 3)  v0/t0 v1/t1 ... vn/tn
+      // 4)  v0/t0/n0 ... vn/tn/nn
+      bool done=false;
+      while(!done)
+      {
+	// read entry
+	signed int vi, vt=-1, vn=-1;
+	ifs >> vi;
+	unsigned char c = ifs.get();
+
+	if(c == '/')
+	{
+	  c = ifs.get();
+	  if(c != '/') { ifs.unget(); ifs >> vt; c = ifs.get(); }
+	  if(c == '/') { ifs >> vn; c = ifs.get(); }
+	}
+
+	// sanity check
+	assert(vt != 0 && vn != 0 && vi != 0);
+
+	// store in polygon
+        if(vt != -1) { assert(vt-1 < textureCoord_list->size()); tidx.push_back(vt-1); }
+        if(vn != -1) { assert(vn-1 < normal_list->size()); nidx.push_back(vn-1); }
+	if(vi != -1) { assert(vi-1 < vertex_list->size()); vidx.push_back(vi-1); }
+
+	// eat spaces and end-of-lines
+	ifs.unget();
+	c = ifs.get();
+	while(ifs.good() && (c == ' ' ||c == '\r' || c == '\n'))
+	{
+	  if(c == '\r' || c == '\n') done = true;
+	  c = ifs.get();
+	}
+	ifs.unget();
+
+        // sanity check
+        assert(tidx.empty() || tidx.size() == vidx.size());
+        assert(nidx.empty() || nidx.size() == vidx.size());
+
+        // store triangle
+        if(vidx.size() >= 3)
+        {
+          size_t m=vidx.size() - 2;
+          size_t l=vidx.size() - 1;
+          if(tidx.empty() && nidx.empty()) triangle_list.push_back( triangle(vidx[0], vidx[m], vidx[l], vertex_list) );
+          if(tidx.empty() && !nidx.empty()) triangle_list.push_back( triangle(vidx[0], vidx[m], vidx[l], vertex_list,
+									      nidx[0], nidx[m], nidx[l], normal_list) );
+          if(!tidx.empty() && nidx.empty()) triangle_list.push_back( triangle(vidx[0], vidx[m], vidx[l], vertex_list,
+									      tidx[0], tidx[m], tidx[l], textureCoord_list) );
+          if(!tidx.empty() && !nidx.empty()) triangle_list.push_back( triangle(vidx[0], vidx[m], vidx[l], vertex_list,
+									       nidx[0], nidx[m], nidx[l], normal_list,
+									       tidx[0], tidx[m], tidx[l], textureCoord_list) );
+        }
+      }
+    }
+    else { ifs.unget(); skipLine(ifs); }
+  }
+
+  // Done.
+}
diff --git a/hw6/src/intersectionPoint.cpp b/hw6/src/intersectionPoint.cpp
new file mode 100644
index 0000000..5b1d15e
--- /dev/null
+++ b/hw6/src/intersectionPoint.cpp
@@ -0,0 +1,342 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "shader_base.h"
+#include "intersectionPoint.h"
+
+/////////////////
+// Constructor //
+/////////////////
+intersectionPoint::intersectionPoint(void)
+{
+  _hit = false;
+}
+
+
+intersectionPoint::intersectionPoint(const ray& r, float rayParameter, const std::shared_ptr<const shader_base>& shader, const vec3d& normal, const vec3d& axis, const vec2d& textureCoordinate)
+{
+  // copy
+  _ray = r;
+  _rayParameter = rayParameter;
+  _hit = true;
+  _shader = shader;
+  _normal = normalize(normal);
+  _axis = normalize(axis);
+  _textureCoordinate = textureCoordinate;
+
+  // compute position
+  _position = _ray(_rayParameter);
+}
+
+
+intersectionPoint::intersectionPoint(const intersectionPoint& ip)
+{
+  _hit = ip._hit;
+
+  // copy remainder if hit
+  if(_hit)
+  {
+    _ray = ip._ray;
+    _rayParameter = ip._rayParameter;
+    _shader = ip._shader;
+    _normal = ip._normal;
+    _position = ip._position;
+    _axis = ip._axis;
+    _textureCoordinate = ip._textureCoordinate;
+  }
+  else _shader = nullptr;
+}
+
+///////////////
+// Operators //
+///////////////
+intersectionPoint& intersectionPoint::operator=(const intersectionPoint& ip)
+{
+  _assign(ip);
+  return *this;
+}
+
+
+bool intersectionPoint::operator<(const intersectionPoint& ip) const
+{
+  // handle case where either one of the intersectionPoints is not a hit
+  // => assume no-hit equals a hit at infinity
+  if(!_hit) return false;
+  if(!ip._hit) return true;
+
+  // decide based on rayParameter
+  return _rayParameter < ip._rayParameter;
+}
+
+
+bool intersectionPoint::operator>(const intersectionPoint& ip) const
+{
+  // handle case where either one of the intersectionPoints is not a hit
+  // => assume no-hit equals a hit at infinity
+  if(!_hit) return true;
+  if(!ip._hit) return false;
+
+  // decide based on rayParameter
+  return _rayParameter > ip._rayParameter;
+}
+
+
+bool intersectionPoint::operator<(const lightSample& ls) const
+{
+  // handle case where this is not a hit
+  if(!_hit) return false;
+
+  // decide based on rayParameter
+  return _rayParameter < ls.distance();
+}
+
+
+bool intersectionPoint::operator>(const lightSample& ls) const
+{
+  // handle case where this is not a hit
+  if(!_hit) return true;
+
+  // decide based on rayParameter
+  return _rayParameter > ls.distance();
+}
+
+////////////////
+// Inspectors //
+////////////////
+bool intersectionPoint::isHit(void) const
+{
+  return _hit;
+}
+
+
+shaderProperties intersectionPoint::getShaderProperties(void) const
+{
+  assert(hasShader());
+  return _shader->properties(*this);
+}
+
+
+bool intersectionPoint::hasShader(void) const
+{
+  return (_shader != nullptr);
+}
+
+
+float intersectionPoint::distance(const intersectionPoint& ip) const
+{
+  // set distance to infinity of one of the two points is not a hit
+  if(!_hit || !ip._hit) return +LARGE;
+
+  // compute distance
+  return _position.distance(ip._position);
+}
+
+
+const vec3d& intersectionPoint::position(void) const
+{
+  return _position;
+}
+
+
+const vec3d& intersectionPoint::direction(void) const
+{
+  return _ray.direction();
+}
+
+
+const vec2d& intersectionPoint::textureCoordinate(void) const
+{
+  return _textureCoordinate;
+}
+
+
+const vec3d& intersectionPoint::normal(void) const
+{
+  return _normal;
+}
+
+
+coordinateTransformation intersectionPoint::shadingFrame(void) const
+{
+  // transform => to global shading frame
+  // inverseTransform => to local shading frame
+  return coordinateTransformation(_normal, _axis);
+}
+
+
+//////////////
+// Mutators //
+//////////////
+void intersectionPoint::transform(const transformation3d& t)
+{
+  // sanity check
+  if(!_hit) return;
+
+  /// transform
+  _ray.transform(t);
+  _position = t.transformPoint(_position);
+  _normal = t.transformNormal(_normal);
+  _axis = t.transformNormal(_axis);
+
+  // recompute the ray parameter (to account for potential scaling)
+  _rayParameter = _ray(_position);
+}
+
+
+void intersectionPoint::inverseTransform(const transformation3d& t)
+{
+  // sanity check
+  if(!_hit) return;
+
+  // inverse transform
+  _ray.inverseTransform(t);
+  _position = t.inverseTransformPoint(_position);
+  _normal = t.inverseTransformNormal(_normal);
+  _axis = t.inverseTransformNormal(_axis);
+
+  // recompute the ray parameter (to account for potential scaling)
+  _rayParameter = _ray(_position);
+}
+
+
+void intersectionPoint::transformShadingFrame(const transformation3d& sft)
+{
+  // sanity check
+  if(!_hit) return;
+
+  // Note: shading frame transformation are defined
+  //       with respect to the local shading frame (i.e., N=Z, axis=X)
+  transformation3d t = shadingFrame();
+
+  // transform
+  _normal = t.transformNormal( sft.transformNormal(vec3d(0.0f, 0.0f, 1.0f)) );
+  _axis = t.transformNormal( sft.transformNormal(vec3d(1.0f, 0.0f, 0.0f)) );
+
+  // Done.
+}
+
+
+void intersectionPoint::inverseTransformShadingFrame(const transformation3d& sft)
+{
+  // sanity check
+  if(!_hit) return;
+
+  // Note: shading frame transformation are defined
+  //       with respect to the local shading frame (i.e., N=Z, axis=X)
+  // Note: this transformation will not undo the effects of
+  //       transformShadingFrame since the local shading frame
+  //       is altered by the transformation (and thus the frame
+  //       with respect to which the inverseTransformation is 
+  //       applied)
+  transformation3d t = shadingFrame();
+
+  // transform
+  _normal = t.transformNormal( sft.inverseTransformNormal(vec3d(0.0f, 0.0f, 1.0f)) );
+  _axis = t.transformNormal( sft.inverseTransformNormal(vec3d(1.0f, 0.0f, 0.0f)) );
+
+  // Done.
+}
+
+
+void intersectionPoint::setShader(const std::shared_ptr<const class shader_base>& shader)
+{
+  _shader = shader;
+}
+
+
+/////////////
+// Methods //
+/////////////
+color intersectionPoint::shade(const vec3d& out) const
+{
+  assert(hasShader());
+  if(!_hit) return color(0.0f);
+  return _shader->shade(*this, out);
+}
+
+color intersectionPoint::shade(const lightSample& ls) const
+{
+  assert(hasShader());
+  if(!_hit) return color(0.0f);
+  return _shader->shade(*this, ls.directionToLight()) * ls.emittance();
+}
+
+
+float intersectionPoint::reflectivity(void) const
+{
+  assert(hasShader());
+
+  // get reflectivity
+  float albedo = _shader->reflectivity(*this);
+  
+  // cannot reflect more than 100%
+  assert(albedo <= 1.0f);
+
+  // Done.
+  return albedo;
+}
+
+
+color intersectionPoint::reflectance(const vec3d& out) const
+{
+  assert(hasShader());
+  return _shader->reflectance(*this, out);
+}
+
+
+brdfSample intersectionPoint::sample(float r1, float r2) const
+{
+  assert(hasShader());
+  return _shader->sample(*this, r1, r2);
+}
+
+
+color intersectionPoint::emittance(void) const
+{
+  assert(hasShader());
+  return _shader->emittance(*this);
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void intersectionPoint::_assign(const intersectionPoint& ip)
+{
+  // sanity check
+  if(&ip == this) return;
+
+  // copy if hit
+  _hit = ip._hit;
+  if(_hit)
+  {
+    _ray = ip._ray;
+    _rayParameter = ip._rayParameter;
+    _position = ip._position;
+    _normal = ip._normal;
+    _axis = ip._axis;
+    _textureCoordinate = ip._textureCoordinate;
+    _shader = ip._shader;
+  }
+  else _shader = nullptr;
+}
+
+
+void intersectionPoint::_swap(intersectionPoint& ip)
+{
+  swap(_ray, ip._ray);
+  std::swap(_hit, ip._hit);
+  std::swap(_rayParameter, ip._rayParameter);
+  swap(_position, ip._position);
+  swap(_normal, ip._normal);
+  swap(_axis, ip._axis);
+  swap(_textureCoordinate, ip._textureCoordinate);
+  std::swap(_shader, ip._shader);
+}
+
diff --git a/hw6/src/interval.cpp b/hw6/src/interval.cpp
new file mode 100644
index 0000000..4323cbd
--- /dev/null
+++ b/hw6/src/interval.cpp
@@ -0,0 +1,154 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "interval.h"
+#include "constants.h"
+
+//////////////////
+// Constrructor //
+//////////////////
+interval::interval(float lower, float upper)
+{
+  _lower = lower;
+  _upper = upper;
+
+  // ensure that _lower < _upper
+  if(_upper < _lower) std::swap(_upper, _lower);
+}
+
+
+interval::interval(const interval& i)
+{
+  _lower = i._lower;
+  _upper = i._upper;
+}
+
+
+
+///////////////
+// Operators //
+///////////////
+interval& interval::operator=(const interval& i)
+{
+  _assign(i);
+  return *this;
+}
+
+
+interval interval::operator+(float v) const
+{
+  return interval(_lower + v, _upper + v); 
+}
+
+
+interval interval::operator-(float v) const
+{
+  return interval(_lower - v, _upper - v); 
+}
+
+
+interval interval::operator*(float v) const
+{
+  return interval(_lower * v, _upper * v); 
+}
+
+
+interval interval::operator/(float v) const
+{
+  return interval(_lower / v, _upper / v); 
+}
+    
+
+interval& interval::operator+=(float v)
+{
+  _lower += v;
+  _upper += v;
+  return *this;
+}
+
+interval& interval::operator-=(float v)
+{
+  _lower -= v;
+  _upper -= v;
+  return *this;
+}
+
+
+interval& interval::operator*=(float v)
+{
+  _lower *= v;
+  _upper *= v;
+
+  // ensure that _lower < _upper
+  if(_upper < _lower) std::swap(_upper, _lower);
+
+  // Done.
+  return *this;
+}
+
+interval& interval::operator/=(float v)
+{
+  _lower /= v;
+  _upper /= v;
+
+  // ensure that _lower < _upper
+  if(_upper < _lower) std::swap(_upper, _lower);
+
+  // Done.
+  return *this;
+}
+
+
+////////////////
+// Inspectors //
+////////////////
+float interval::lower(void) const
+{
+  return _lower;
+}
+
+
+float interval::upper(void) const
+{
+  return _upper;
+}
+
+
+bool interval::empty(void) const
+{
+  return (_upper - _lower < EPSILON);
+}
+
+
+
+//////////////
+// Mutators //
+//////////////
+void interval::intersect(const interval& i)
+{
+  _lower = std::max(_lower, i._lower);
+  _upper = std::min(_upper, i._upper);
+}
+
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void interval::_assign(const interval& i)
+{
+  _lower = i._lower;
+  _upper = i._upper;
+}
+
+
+void interval::_swap(interval& i)
+{
+  std::swap(_lower, i._lower);
+  std::swap(_upper, i._upper);
+}
diff --git a/hw6/src/lightSample.cpp b/hw6/src/lightSample.cpp
new file mode 100644
index 0000000..cfe4ee5
--- /dev/null
+++ b/hw6/src/lightSample.cpp
@@ -0,0 +1,120 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "lightSample.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+lightSample::lightSample(const vec3d& direction,
+			 const color& emittance,
+			 float distance,
+			 float pdf,
+			 float foreshortening)
+{
+  float length = direction.length();
+  _direction = (length < EPSILON) ? vec3d(0.0f, 0.0f, 0.0f) : direction / length;
+  _emittance = emittance;
+  _distance = distance;
+  _pdf = std::max(pdf, 0.0f);
+  _foreshortening = std::max(foreshortening, 0.0f);
+}
+
+
+lightSample::lightSample(const lightSample& ls)
+{
+  _direction = ls._direction;
+  _emittance = ls._emittance;
+  _distance = ls._distance;
+  _pdf = ls._pdf;
+  _foreshortening = ls._foreshortening;
+}
+
+
+///////////////
+// Operators //
+///////////////
+lightSample& lightSample::operator=(const lightSample& ls)
+{
+  _assign(ls);
+  return(*this);
+}
+
+
+const color& lightSample::operator()(void) const
+{
+  return _emittance;
+}
+
+
+////////////////
+// Inspectors //
+////////////////
+const vec3d& lightSample::directionToPoint(void) const
+{
+  return _direction;
+}
+
+
+vec3d lightSample::directionToLight(void) const
+{
+  return -_direction;
+}
+
+
+const color& lightSample::emittance(void) const
+{
+  return _emittance;
+}
+
+
+float lightSample::distance(void) const
+{
+  return _distance;
+}
+
+
+float lightSample::pdf(void) const
+{
+  return _pdf;
+}
+
+
+float lightSample::foreshortening(void) const
+{
+  return _foreshortening;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void lightSample::_assign(const lightSample& ls)
+{
+  // sanity check
+  if(&ls == this) return;
+
+  // copy
+  _direction = ls._direction;
+  _emittance = ls._emittance;
+  _distance = ls._distance;
+  _pdf = ls._pdf;
+  _foreshortening = ls._foreshortening;
+}
+
+
+void lightSample::_swap(lightSample& ls)
+{
+  swap(_direction, ls._direction);
+  swap(_emittance, ls._emittance);
+  std::swap(_distance, ls._distance);
+  std::swap(_pdf, ls._pdf);
+  std::swap(_foreshortening, ls._foreshortening);
+}
diff --git a/hw6/src/lightsourceGeometry.cpp b/hw6/src/lightsourceGeometry.cpp
new file mode 100644
index 0000000..3f028aa
--- /dev/null
+++ b/hw6/src/lightsourceGeometry.cpp
@@ -0,0 +1,54 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "lightsourceShader.h"
+#include "lightsourceGeometry.h"
+
+/////////////////
+// Constructor //
+/////////////////
+lightsourceGeometry::lightsourceGeometry(void)
+  : boundedCompound()
+{
+  // Nothing.
+}
+
+
+lightsourceGeometry::lightsourceGeometry(const std::shared_ptr<const boundedPrimitive>& geometry, const std::shared_ptr<const lightsource_base>& ls, const std::shared_ptr<const shader_base>& material)
+  : boundedCompound()
+{
+  assert(geometry && ls);
+  _geometry.push_back(geometry);
+  _shader = std::shared_ptr<const shader_base>(new lightsourceShader(ls, material));
+
+  // Done.
+  initializeBoundingBox();
+}
+
+
+/////////////
+// Methods //
+/////////////
+bool lightsourceGeometry::hasShader(void) const
+{
+  // always has a shader by construction
+  return true;
+}
+
+
+const std::vector<std::shared_ptr<const boundedPrimitive>>& lightsourceGeometry::compounds(void) const
+{
+  return _geometry;
+}
+
+
+void lightsourceGeometry::_print(std::ostream& s) const
+{
+  s << "lightsourceGeometry (" << _bb << ") -> [" << *_shader << "]";
+}
diff --git a/hw6/src/lightsourceShader.cpp b/hw6/src/lightsourceShader.cpp
new file mode 100644
index 0000000..f399f8e
--- /dev/null
+++ b/hw6/src/lightsourceShader.cpp
@@ -0,0 +1,72 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "lightsourceShader.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+lightsourceShader::lightsourceShader(const std::shared_ptr<const lightsource_base>& lightsource, const std::shared_ptr<const shader_base>& reflectanceShader)
+{
+  assert(lightsource);
+  _lightsource = lightsource;
+  _reflectanceShader = reflectanceShader;
+}
+
+
+/////////////
+// Methods //
+/////////////
+color lightsourceShader::shade(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  color result = _lightsource->_emittance(ip); 
+  if(_reflectanceShader) result += _reflectanceShader->shade(ip, light_dir);
+  return result;
+}
+
+
+color lightsourceShader::reflectance(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  return (_reflectanceShader) ? _reflectanceShader->reflectance(ip, light_dir) : color();
+}
+
+
+brdfSample lightsourceShader::sample(const intersectionPoint& ip, float r1, float r2) const
+{
+  return (_reflectanceShader) ? _reflectanceShader->sample(ip, r1, r2) : brdfSample();
+}
+
+
+float lightsourceShader::reflectivity(const intersectionPoint& ip) const
+{
+  return (_reflectanceShader) ? _reflectanceShader->reflectivity(ip) : 0.0f;
+}
+
+
+shaderProperties lightsourceShader::properties(const intersectionPoint& ip) const
+{
+  return (_reflectanceShader) ? _reflectanceShader->properties(ip) : shaderProperties(false, false);
+}
+
+
+color lightsourceShader::emittance(const intersectionPoint& ip) const
+{
+  return _lightsource->_emittance(ip);
+}
+
+///////////////////////
+// Protected Methods //
+///////////////////////
+void lightsourceShader::_print(std::ostream& s) const
+{
+  s << "LightsourceShader: light=" << *_lightsource << ", reflectance shader=";
+  if(_reflectanceShader) s << *_reflectanceShader;
+  else s << "None.";
+}
diff --git a/hw6/src/linear_intersector.cpp b/hw6/src/linear_intersector.cpp
new file mode 100644
index 0000000..c7cb37e
--- /dev/null
+++ b/hw6/src/linear_intersector.cpp
@@ -0,0 +1,53 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "linear_intersector.h"
+
+//////////////////
+// Constructors //
+//////////////////
+linear_intersector::linear_intersector(void)
+  : intersector_base()
+{
+  // Do nothing
+}
+
+
+linear_intersector::linear_intersector(const std::vector<std::shared_ptr<const boundedPrimitive>>& compounds)
+  : intersector_base()
+{
+  _compounds = compounds;
+}
+
+  
+/////////////
+// Methods //
+/////////////
+intersectionPoint linear_intersector::intersect(const ray& r) const
+{
+  intersectionPoint ip;
+
+  // if no compounds registered => no hit.
+  if(_compounds.empty()) return ip;
+
+  // cycle through the list
+  for(auto itr=_compounds.begin(); itr != _compounds.end(); itr++)
+  {
+    // intersect
+    intersectionPoint newIp = (*itr)->intersect(r);
+
+    // keep track of closest
+    if(newIp < ip) ip = newIp;
+  }
+
+  // Done.
+  return ip;
+}
+
+
+
diff --git a/hw6/src/mat3d.cpp b/hw6/src/mat3d.cpp
new file mode 100644
index 0000000..7674777
--- /dev/null
+++ b/hw6/src/mat3d.cpp
@@ -0,0 +1,260 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include <algorithm>
+
+#include "mat3d.h"
+
+
+/////////////////
+// Constructor //
+/////////////////
+mat3d::mat3d(void)
+{
+  clear(0.0f);
+}
+
+
+mat3d::mat3d(mat3d::value_type diag)
+  : mat3d()
+{
+  setDiagonal(diag);
+}
+
+
+mat3d::mat3d(const vec3d& X, const vec3d& Y, const vec3d& Z)
+{
+  for(size_type i=0; i < 3; i++)
+  {
+    this->operator()(i,0) = X[i];
+    this->operator()(i,1) = Y[i];
+    this->operator()(i,2) = Z[i];
+  }
+}
+
+
+mat3d::mat3d(const mat3d& m)
+{
+  _data = m._data;
+}
+
+
+////////////////
+// Inspectors //
+////////////////
+mat3d::iterator mat3d::begin(void)
+{
+  return _data.begin();
+}
+
+
+mat3d::const_iterator mat3d::begin(void) const
+{
+  return _data.begin();
+}
+
+
+mat3d::iterator mat3d::end(void)
+{
+  return _data.end();
+}
+
+
+mat3d::const_iterator mat3d::end(void) const
+{
+  return _data.end();
+}
+
+
+//////////////
+// Mutators //
+//////////////
+void mat3d::clear(mat3d::value_type value)
+{
+  std::fill(begin(), end(), value);
+}
+
+
+void mat3d::setDiagonal(mat3d::value_type value)
+{
+  (*this)(0,0) = (*this)(1,1) = (*this)(2,2) = value;
+}
+
+
+mat3d& mat3d::transpose(void)
+{
+  for(size_type row=0; row < height(); row++)
+    for(size_type column=row+1; column < width(); column++)
+      std::swap( (*this)(row,column), (*this)(column,row) );
+  return *this;
+}
+
+
+
+///////////////
+// Operators //
+///////////////
+mat3d& mat3d::operator=(const mat3d& m)
+{
+  _assign(m);
+  return *this;
+}
+
+
+mat3d::reference mat3d::operator()(mat3d::size_type row, mat3d::size_type col)
+{
+  assert(row < height() && col < width());
+  return _data[ row*width() + col];
+}
+
+
+mat3d::const_reference mat3d::operator()(mat3d::size_type row, mat3d::size_type col) const
+{
+  assert(row < height() && col < width());
+  return _data[ row*width() + col];
+}
+
+
+mat3d mat3d::operator+(const mat3d& m) const
+{
+  mat3d result;
+  std::transform(begin(), end(), m.begin(), result.begin(), [](const_reference a, const_reference b)
+  {
+    return a+b;
+  });
+  return result;
+}
+
+
+mat3d mat3d::operator-(const mat3d& m) const 
+{
+  mat3d result;
+  std::transform(begin(), end(), m.begin(), result.begin(), [](const_reference a, const_reference b)
+  {
+    return a-b;
+  });
+  return result;
+}
+
+
+mat3d mat3d::operator*(const mat3d& m) const 
+{ 
+  mat3d result;
+  for(size_type i=0; i < result.height(); i++)
+    for(size_type j=0; j < result.width(); j++)
+      for(size_type k=0; k < width(); k++)
+	result(i,j) += (*this)(i,k) * m(k, j);
+  return result;
+}
+
+
+vec3d mat3d::operator*(const vec3d& v) const 
+{ 
+  vec3d result;
+  for(size_type i=0; i < height(); i++)
+    for(size_type j=0; j < width(); j++)
+      result[i] += v[j] * (*this)(i,j);
+  return result;
+}
+
+
+mat3d mat3d::operator*(mat3d::value_type scale) const 
+{
+  mat3d result;
+  std::transform(begin(), end(), result.begin(), [&](const_reference v)
+  {
+    return v * scale;
+  });
+  return result;
+}
+
+mat3d mat3d::operator/(mat3d::value_type scale) const 
+{
+  mat3d result;
+  std::transform(begin(), end(), result.begin(), [&](const_reference v)
+  {
+    return v / scale;
+  });
+  return result;
+}
+
+
+mat3d& mat3d::operator+=(const mat3d& m) 
+{ 
+  std::transform(begin(), end(), m.begin(), begin(), [](const_reference a, const_reference b)
+  {
+    return a+b;
+  });
+  return *this; 
+}
+
+
+mat3d& mat3d::operator-=(const mat3d& m) 
+{
+  std::transform(begin(), end(), m.begin(), begin(), [](const_reference a, const_reference b)
+  {
+    return a-b;
+  });
+  return *this; 
+}
+
+
+mat3d& mat3d::operator*=(const mat3d& m) 
+{
+  *this = *this * m;
+  return *this;
+}
+
+
+mat3d& mat3d::operator*=(mat3d::value_type scale) 
+{
+  std::for_each(begin(), end(), [&](reference v)
+  {
+    v *= scale;
+  });
+  return *this; 
+}
+
+
+mat3d& mat3d::operator/=(mat3d::value_type scale) 
+{
+  std::for_each(begin(), end(), [&](reference v)
+  {
+    v /= scale;
+  });
+  return *this; 
+}
+  
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void mat3d::_swap(mat3d& m)
+{
+  if(&m == this) return;
+  std::swap(_data, m._data);
+}
+
+
+void mat3d::_assign(const mat3d& m)
+{
+  if(&m == this) return;
+  _data = m._data;
+}
+
+
+vec3d mat3d::_premultiply(const vec3d& v) const
+{
+  // result = v * *this
+  vec3d result;
+  for(size_type i=0; i < height(); i++)
+    for(size_type j=0; j < width(); j++)
+      result[j] += v[i] * (*this)(i,j);
+  return result;
+}
diff --git a/hw6/src/nearestTexture.cpp b/hw6/src/nearestTexture.cpp
new file mode 100644
index 0000000..258ebd8
--- /dev/null
+++ b/hw6/src/nearestTexture.cpp
@@ -0,0 +1,52 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "nearestTexture.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+nearestTexture::nearestTexture(bool repeat)
+  : texture_base(repeat)
+{
+  // Do nothing.
+}
+
+
+nearestTexture::nearestTexture(const nearestTexture& src)
+  : texture_base(src)
+{
+  // Do nothing
+}
+
+
+///////////////
+// Operators //
+///////////////
+nearestTexture& nearestTexture::operator=(const nearestTexture& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+image::value_type nearestTexture::operator()(const vec2d& textureCoord) const
+{
+  return _at(floor(textureCoord.u * width()), 
+	     floor(textureCoord.v * height()));
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void nearestTexture::_print(std::ostream& s) const
+{
+  s << "Nearest texture (" << this->width() << "x" << this->height() << ")";
+}
diff --git a/hw6/src/normalMap.cpp b/hw6/src/normalMap.cpp
new file mode 100644
index 0000000..9cce3c3
--- /dev/null
+++ b/hw6/src/normalMap.cpp
@@ -0,0 +1,44 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "normalMap.h"
+#include "coordinateTransform.h"
+
+//////////////////
+// Constructors //
+//////////////////
+normalMap::normalMap(const std::shared_ptr<const texture_base>& map, const std::shared_ptr<const shader_base>& shader)
+  : shadingFrameTransformation(shader)
+{
+  _map = map;
+}
+
+/////////////
+// Methods //
+/////////////
+transformation3d normalMap::_transformation(const vec2d& textureCoord) const
+{
+  // get texel
+  assert(_map);
+  color texel = (*_map)(textureCoord);
+
+  // get desired local normal
+  vec3d normal(texel.r, texel.g, texel.b);
+  normal.normalize();
+
+  // create coordinate system. Keep U aligned as close as possible to the X axis.
+  return coordinateTransformation(normal, vec3d(1.0f, 0.0, 0.0));
+}
+
+
+void normalMap::_print(std::ostream& s) const
+{
+  s << "normalMap (" << *_map << ") -> {" << *_shader << "}";
+}
+
diff --git a/hw6/src/pathtracing.cpp b/hw6/src/pathtracing.cpp
new file mode 100644
index 0000000..dc9dda1
--- /dev/null
+++ b/hw6/src/pathtracing.cpp
@@ -0,0 +1,175 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "ray_util.h"
+#include "pathtracing.h"
+#include "random_number.h"
+
+//////////////////
+// Constructors //
+//////////////////
+pathtracing::pathtracing(unsigned int samplesPerPixel, bool directOnly)
+{
+  _samples = samplesPerPixel;
+  _directOnly = directOnly;
+}
+
+
+/////////////
+// Methods //
+/////////////
+image pathtracing::render(const scene& s) const
+{
+  image result(s.getCamera().width(), s.getCamera().height());
+
+  // for every pixel
+  for(image::size_type y=0; y < result.height(); y++)
+    for(image::size_type x=0; x < result.width(); x++)
+    {
+      color pixelRadiance(0.0f, 0.0f, 0.0f);
+
+      // for every sample
+      for(unsigned int sample = 0; sample < _samples; sample++)
+      {
+      	color sampleRadiance(0.0f, 0.0f, 0.0f);
+
+      	// generate random camera ray through pixel:
+      	float px = (float)(x) + random_float();	float py = (float)(y) + random_float();
+      	ray r = s.getCamera()(px, py);
+
+      	// get initial intersection point
+      	intersectionPoint ip = s.intersect(r);
+
+      	// get radiance from directly visible *area* light sources
+      	if(ip.isHit())
+      	  sampleRadiance += ip.emittance();
+
+      	// get scene radiance
+      	sampleRadiance += radiance(s, r, ip);
+
+      	// store
+      	pixelRadiance += sampleRadiance / (float)(_samples);
+      }
+
+      // store in image
+      result(x,y) = pixelRadiance;
+    }
+
+  // Done.
+  return result;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+color pathtracing::radiance(const scene& s, const ray& r, const intersectionPoint& ip) const
+{
+  color radiance(0.0f, 0.0f, 0.0f);
+
+  // if scene hit
+  if(ip.isHit())
+  {
+    // solve rendering equation
+    radiance = directRadiance(s, ip);
+    if(!_directOnly) radiance += indirectRadiance(s, ip);
+  }
+
+  // if not hit
+  else if(s.hasEnvironmentMap())
+  {
+    radiance += s.evaluateEnvironmentMap(r.direction());
+  }
+
+  // Done.
+  return radiance;
+}
+
+
+color pathtracing::directRadiance(const scene& s, const intersectionPoint& ip) const
+{
+  // HW6: implement this. Compute the direct radiance incident
+  //      at the intersection point 'ip' according to the
+  //      rendering equation.
+  // Modifies: nothing
+  // Returns: computed direct radiance.
+
+  color result = color(0.0f);
+
+  // for every light source,
+  for (int l = 0; l < s.numberOfLightsources(); l++) {
+    // sample the light source
+    lightSample ls = s.getLightsource(l).emittanceAt(ip.position(), random_float(), random_float());
+
+    // check if occluded
+    ray shadowRay = createRay(ip, ls.directionToLight());
+    intersectionPoint shadowIp = s.intersect(shadowRay);
+
+    // if not occluded,
+    if (ls < shadowIp && ls.distance() > sqrt(EPSILON)) {
+      float cosine = ls.directionToLight().dot(ip.normal()) / ls.distance();
+
+      // if no division by zero,
+      if (ls.pdf() > EPSILON && cosine >= 0) {
+        // compute radiance via rendering equation for direct illumination
+        result += (ip.reflectance(ls.directionToLight()) // fr(x, -psi<->theta) (brdf)
+                      * ls.emittance() // Le(y->psi)
+                      * cosine // cos(nx, -psi)
+                      * ls.foreshortening() // cos(ny, psi)
+                      / ls.distance() // r^2 (other r in cosine calculation)
+                      / ls.pdf() // pdf (monte-carlo integration probability)
+                    );
+      }
+
+    }
+
+  }
+
+  return result;
+}
+
+
+color pathtracing::indirectRadiance(const scene& s, const intersectionPoint& ip) const
+{
+  // HW6: implement this. Computed the indirect radiance incident
+  //      at the intersection point 'ip' according to the rendering
+  //      equation.
+  // Modifies: nothing
+  // Returns: computed indirect radiance.
+
+  color result = color(0.0f);
+
+  // if absorption falls above a random value, end recursion (russian roulette)
+  if (1 - ip.reflectivity() > random_float(1.0f)) { return result; }
+
+  // sample the surface
+  brdfSample brdf = ip.sample(random_float(), random_float());
+
+  // create exitant ray
+  ray exitantRay = createRay(ip, brdf.exitantDirection());
+
+  // recursively compute radiance from reflected point
+  color reflectedColor = radiance(s, exitantRay, s.intersect(exitantRay));
+
+  // compute cosine
+  float cosine = brdf.exitantDirection().dot(ip.normal());
+
+  // if no division by zero via pdf and cosines are not negative,
+  if (brdf.pdf() > EPSILON && cosine > EPSILON) {
+    // compute radiance via rendering equation for indirect illumination
+    result += (brdf.reflectance()   // fr(x, -psi<->theta) (brdf)
+                * reflectedColor    // Le(y->psi)
+                * cosine            // cos(nx, -psi)
+                / brdf.pdf()        // pdf (monte-carlo integration probability)
+                / ip.reflectivity() // russian roulette
+              );
+
+  }
+
+  return result;
+}
diff --git a/hw6/src/phongBrdf.cpp b/hw6/src/phongBrdf.cpp
new file mode 100644
index 0000000..939f3a1
--- /dev/null
+++ b/hw6/src/phongBrdf.cpp
@@ -0,0 +1,133 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "constants.h"
+#include "phongBrdf.h"
+#include "coordinateTransform.h"
+
+//////////////////
+// Constructors //
+//////////////////
+phongBrdf::phongBrdf(const color& albedo, float sharpness)
+{
+  _albedo = albedo;
+  _sharpness = sharpness;
+}
+
+
+phongBrdf::phongBrdf(const phongBrdf& src)
+{
+  _albedo = src._albedo;
+  _sharpness = src._sharpness;
+}
+
+
+///////////////
+// Operators //
+///////////////
+phongBrdf& phongBrdf::operator=(const phongBrdf& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+/////////////
+// Methods //
+/////////////
+color phongBrdf::shade(const vec3d& in, const vec3d& out) const
+{
+  // sanity check (below horizon)
+  if(in.z < 0.0f || out.z < 0.0f) return color(0.0f);
+
+  // compute reflected direction (simplies when n=(0,0,1))
+  vec3d reflected(-in.x, -in.y, in.z);
+
+  // evaluate phong
+  return _albedo * std::pow(std::max( reflected.dot(out), 0.0f), _sharpness);
+}
+
+
+color phongBrdf::reflectance(const vec3d& in, const vec3d& out) const
+{
+  // use shade evaluation times a normalization factor to ensure
+  // conservation of enegery.
+  return shade(in, out) * (_sharpness + 2.0f) / (2.0f * PI);
+}
+
+
+brdfSample phongBrdf::sample(const vec3d& in, float r1, float r2) const
+{
+  // sanity check
+  if(in.z < 0.0f) return brdfSample();
+
+  // compute reflected direction
+  vec3d reflected(-in.x, -in.y, in.z);
+
+  // sample hemisphere around reflected direction.
+  vec3d out( sqrt( 1.0f - pow(r1, 2.0f / (_sharpness + 1.0f)) ) * cos(2.0f * PI * r2),
+	     sqrt( 1.0f - pow(r1, 2.0f / (_sharpness + 1.0f)) ) * sin(2.0f * PI * r2),
+	     pow(r1, 1.0f / (_sharpness + 1.0f)) );
+
+  // transform to global coord
+  coordinateTransformation trans(reflected);
+  out = trans.transformDirection(out);
+
+  // compute pdf
+  float pdf = 0.0f;
+  if(out.z >= 0.0f) 
+    pdf = (_sharpness + 1.0f) / (2.0f * PI) * pow(reflected.dot(out), _sharpness); 
+
+  // Done.
+  return brdfSample(out, pdf, this->reflectance(in, out));
+}
+
+
+bool phongBrdf::isSpecular(void) const
+{
+  // Consider low roughness to be diffuse.  
+  // Use 5.0f as an arbitrary threshold.
+  return (_sharpness > 5.0f);
+}
+
+
+bool phongBrdf::isDiffuse(void) const
+{
+  return !isSpecular();
+}
+
+
+float phongBrdf::reflectivity(void) const
+{
+  // Done.
+  return (_albedo.r + _albedo.g + _albedo.b) / 3.0f;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void phongBrdf::_assign(const phongBrdf& src)
+{
+  _albedo = src._albedo;
+  _sharpness = src._sharpness;
+}
+
+
+void phongBrdf::_swap(phongBrdf& src)
+{
+  swap(_albedo, src._albedo);
+  std::swap(_sharpness, src._sharpness);
+}
+
+
+void phongBrdf::_print(std::ostream& s) const
+{
+  s << "Phong BRDF: albedo=" << _albedo << ", sharpness=" << _sharpness;
+}
diff --git a/hw6/src/phongReflectanceShader.cpp b/hw6/src/phongReflectanceShader.cpp
new file mode 100644
index 0000000..c5ac57c
--- /dev/null
+++ b/hw6/src/phongReflectanceShader.cpp
@@ -0,0 +1,36 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "phongReflectanceShader.h"
+
+
+/////////////////
+// Constructor //
+/////////////////
+phongReflectanceShader::phongReflectanceShader(const colorReflectanceParameter& albedo, const scalarReflectanceParameter& sharpness)
+  : reflectanceShader_base()
+{
+  _albedo = albedo;
+  _sharpness = sharpness;
+}
+
+
+///////////////////////
+// Protected Methods //
+///////////////////////
+std::unique_ptr<const brdf_base> phongReflectanceShader::make_brdf(const vec2d& textureCoord) const
+{
+  return std::unique_ptr<const brdf_base>(new phongBrdf( _albedo(textureCoord), _sharpness(textureCoord) ));
+}
+
+
+void phongReflectanceShader::_print(std::ostream& s) const
+{
+  s << "Phong Reflectance: albedo=" << _albedo << ", sharpness=" << _sharpness;
+}
diff --git a/hw6/src/pointLightsource.cpp b/hw6/src/pointLightsource.cpp
new file mode 100644
index 0000000..4d4b85d
--- /dev/null
+++ b/hw6/src/pointLightsource.cpp
@@ -0,0 +1,55 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "constants.h"
+#include "pointLightsource.h"
+
+//////////////////
+// Constructors //
+//////////////////
+pointLightsource::pointLightsource(const vec3d& position, const color& power, const vec3d& attenuation)
+{
+  _position = position;
+  _power = power;
+  _attenuation = attenuation;
+}
+
+
+/////////////
+// Methods //
+/////////////
+lightSample pointLightsource::intensityAt(const vec3d& point) const
+{
+  vec3d direction = point - _position;
+  float distance = direction.length();
+  float attenuation = ((_attenuation[2]*distance + _attenuation[1])*distance + _attenuation[0]);
+
+  // Done.
+  return lightSample(direction, _power / attenuation, distance);
+}
+
+
+lightSample pointLightsource::emittanceAt(const vec3d& point, float r1, float r2) const
+{
+  vec3d direction = point - _position;
+  float distance = direction.length();
+
+  // emittance == _power / area sphere
+  // pdf = 1.0 (there is no selection)
+  // foreshortning = 1.0 (everything is normal to the point)
+  return lightSample(direction, _power / (4.0f * PI), distance, 1.0f, 1.0f);  
+}
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void pointLightsource::_print(std::ostream& s) const
+{
+  s << "Point Lightsource: position=" << _position << ", power=" << _power << ", attenuation=" << _attenuation;  
+}
diff --git a/hw6/src/ray.cpp b/hw6/src/ray.cpp
new file mode 100644
index 0000000..18c839d
--- /dev/null
+++ b/hw6/src/ray.cpp
@@ -0,0 +1,83 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include "ray.h"
+
+//////////////////
+// Constructors //
+//////////////////
+ray::ray(const vec3d& origin, const vec3d& direction)
+{
+  _origin = origin;
+  _direction = normalize(direction);
+}
+
+ray::ray(const ray& r)
+{
+  _origin = r._origin;
+  _direction = r._direction;
+}
+
+
+///////////////
+// Operators //
+///////////////
+ray& ray::operator=(const ray& r)
+{
+  _assign(r);
+  return *this;
+}
+
+
+vec3d ray::operator()(float t) const
+{
+  return _origin + t*_direction;
+}
+
+
+float ray::operator()(const vec3d& point) const
+{
+  return _direction.dot(point - _origin);
+}
+
+
+//////////////
+// Mutators //
+//////////////
+ray& ray::transform(const transformation3d& t)
+{
+  _origin = t.transformPoint(_origin);
+  _direction = t.transformDirection(_direction);
+  return *this;
+}
+
+
+ray& ray::inverseTransform(const transformation3d& t)
+{
+  _origin = t.inverseTransformPoint(_origin);
+  _direction = t.inverseTransformDirection(_direction);
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void ray::_swap(ray& r)
+{
+  swap(_origin, r._origin);
+  swap(_direction, r._direction);
+}
+
+
+void ray::_assign(const ray& r)
+{
+  _origin = r._origin;
+  _direction = r._direction;
+}
diff --git a/hw6/src/ray_util.cpp b/hw6/src/ray_util.cpp
new file mode 100644
index 0000000..580f249
--- /dev/null
+++ b/hw6/src/ray_util.cpp
@@ -0,0 +1,27 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "constants.h"
+#include "ray_util.h"
+
+
+ray createRay(const intersectionPoint& ip, const vec3d& dir)
+{
+  return ray(ip.position() + EPSILON * dir, dir);
+}
+
+
+ray reflectRay(const intersectionPoint& ip)
+{
+  // compute reflected direction
+  // Note: ip.direction points toward ip point!
+  vec3d reflectedDir = ip.direction() - 2.0f * (ip.normal().dot(ip.direction())) * ip.normal(); 
+
+  // create ray
+  return createRay(ip, reflectedDir);
+}
diff --git a/hw6/src/raycasting.cpp b/hw6/src/raycasting.cpp
new file mode 100644
index 0000000..e533d5a
--- /dev/null
+++ b/hw6/src/raycasting.cpp
@@ -0,0 +1,47 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "raycasting.h"
+
+/////////////
+// Methods //
+/////////////
+image raycasting::render(const scene& s) const
+{
+  image result(s.getCamera().width(), s.getCamera().height());
+
+  // for every pixel
+  for(image::size_type y=0; y < result.height(); y++)
+    for(image::size_type x=0; x < result.width(); x++)
+    {
+      // generate view ray
+      ray r = s.getCamera()(x,y);
+
+      // intersect scene
+      intersectionPoint ip = s.intersect(r);
+
+      // shade pixel
+      if(ip.isHit())
+      {
+	// for each light source
+	for(unsigned int l=0; l < s.numberOfLightsources(); l++)
+	{
+	  // connect to light source
+	  lightSample ls = s.getLightsource(l).intensityAt(ip.position());
+
+	  // shade
+	  result(x,y) += ip.shade(ls);
+	}
+      }
+      else result(x,y) = color(0.0f, 0.0f, 0.0f);
+    }
+  
+
+  // Done.
+  return result;
+}
diff --git a/hw6/src/recursiveRaytracing.cpp b/hw6/src/recursiveRaytracing.cpp
new file mode 100644
index 0000000..1163b2b
--- /dev/null
+++ b/hw6/src/recursiveRaytracing.cpp
@@ -0,0 +1,94 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "ray_util.h"
+#include "random_number.h"
+#include "recursiveRaytracing.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+recursiveRaytracing::recursiveRaytracing(unsigned int maxDepth, unsigned int samplesPerPixel)
+{
+  _depth = maxDepth;
+  _samples = samplesPerPixel;
+}
+
+ 
+/////////////
+// Methods //
+/////////////
+image recursiveRaytracing::render(const scene& s) const
+{
+  image result(s.getCamera().width(), s.getCamera().height());
+
+  // for every pixel
+  for(image::size_type y=0; y < result.height(); y++)
+    for(image::size_type x=0; x < result.width(); x++)
+    {
+      // for every sample per pixel
+      for(unsigned int sample = 0; sample < _samples; sample++)
+      {
+	// select point in pixel
+	float px = (_samples == 1) ? (float)(x) + 0.5f : (float)(x) + random_float();
+	float py = (_samples == 1) ? (float)(y) + 0.5f : (float)(y) + random_float();
+
+	// generate view ray
+	ray r = s.getCamera()(px,py);
+
+	// recursive ray tracing
+	result(x,y) += traceRay(s, r, 1) / (float)(_samples);
+      }
+    }
+  
+
+  // Done.
+  return result;
+}
+
+
+
+color recursiveRaytracing::traceRay(const scene& s, const ray& r, unsigned int currentDepth) const
+{
+  // intersect
+  intersectionPoint ip = s.intersect(r);
+
+  // if hit
+  color result;
+  if(ip.isHit())
+  {
+    // shade point
+    for(unsigned int l=0; l < s.numberOfLightsources(); l++)
+    {
+      // connect to light source
+      lightSample ls = s.getLightsource(l).intensityAt(ip.position());
+
+      // check if occluded
+      ray shadowRay = createRay(ip, ls.directionToLight());
+      intersectionPoint shadowIp = s.intersect(shadowRay);
+      if(ls < shadowIp)
+	result += ip.shade(ls);
+    }
+
+    // recurse
+    if(currentDepth < _depth && ip.getShaderProperties().specular)
+    {
+      ray reflectedRay = reflectRay(ip);
+      result += ip.shade(reflectedRay.direction()) * traceRay(s, reflectedRay, currentDepth+1);
+    }
+
+  }
+
+  // if not hit, check for environment map
+  else if(s.hasEnvironmentMap())
+    result += s.evaluateEnvironmentMap(r.direction());
+
+  // Done.
+  return result;
+}
diff --git a/hw6/src/reflectanceParameter.cpp b/hw6/src/reflectanceParameter.cpp
new file mode 100644
index 0000000..5b918fb
--- /dev/null
+++ b/hw6/src/reflectanceParameter.cpp
@@ -0,0 +1,140 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "reflectanceParameter.h"
+
+/******************************/
+/* scalarReflectanceParameter */
+/******************************/
+
+/////////////////
+// Constructor //
+/////////////////
+scalarReflectanceParameter::scalarReflectanceParameter(float value)
+{
+  _value = value;
+  _texture = nullptr;
+  _channel = 0.0f; 
+}
+
+
+scalarReflectanceParameter::scalarReflectanceParameter(const std::shared_ptr<const texture_base>& texture, unsigned int channel)
+{
+  _value = 0.0f;
+  _texture = texture;
+  _channel = channel;
+}
+
+
+scalarReflectanceParameter::scalarReflectanceParameter(const scalarReflectanceParameter& src)
+{
+  _value = src._value;
+  _texture = src._texture;
+  _channel = src._channel;
+}
+
+
+//////////////
+// Operator //
+//////////////
+scalarReflectanceParameter& scalarReflectanceParameter::operator=(const scalarReflectanceParameter& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+float scalarReflectanceParameter::operator()(const vec2d& textureCoord) const
+{
+  if(_texture) return (*_texture)(textureCoord)[_channel];
+  else return _value;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void scalarReflectanceParameter::_assign(const scalarReflectanceParameter& src)
+{
+  _value = src._value;
+  _texture = src._texture;
+  _channel = src._channel;
+}
+
+
+void scalarReflectanceParameter::_swap(scalarReflectanceParameter& swp)
+{
+  std::swap(_value, swp._value);
+  std::swap(_texture, swp._texture);
+  std::swap(_channel, swp._channel);
+}
+
+
+
+/*****************************/
+/* colorReflectanceParameter */
+/*****************************/
+
+/////////////////
+// Constructor //
+/////////////////
+colorReflectanceParameter::colorReflectanceParameter(color value)
+{
+  _value = value;
+  _texture = nullptr;
+}
+
+
+colorReflectanceParameter::colorReflectanceParameter(const std::shared_ptr<const texture_base>& texture)
+{
+  _value = color(0.0f);
+  _texture = texture;
+}
+
+
+colorReflectanceParameter::colorReflectanceParameter(const colorReflectanceParameter& src)
+{
+  _value = src._value;
+  _texture = src._texture;
+}
+
+
+//////////////
+// Operator //
+//////////////
+colorReflectanceParameter& colorReflectanceParameter::operator=(const colorReflectanceParameter& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+color colorReflectanceParameter::operator()(const vec2d& textureCoord) const
+{
+  if(_texture) return (*_texture)(textureCoord);
+  else return _value;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void colorReflectanceParameter::_assign(const colorReflectanceParameter& src)
+{
+  _value = src._value;
+  _texture = src._texture;
+}
+
+
+void colorReflectanceParameter::_swap(colorReflectanceParameter& swp)
+{
+  std::swap(_value, swp._value);
+  std::swap(_texture, swp._texture);
+}
+
+
diff --git a/hw6/src/reflectanceShader_base.cpp b/hw6/src/reflectanceShader_base.cpp
new file mode 100644
index 0000000..780f119
--- /dev/null
+++ b/hw6/src/reflectanceShader_base.cpp
@@ -0,0 +1,85 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "reflectanceShader_base.h"
+#include "coordinateTransform.h"
+
+/////////////
+// Methods //
+/////////////
+color reflectanceShader_base::shade(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  // create shading frame (note: in and out point away!)
+  coordinateTransformation ct = ip.shadingFrame();
+  vec3d local_out = ct.inverseTransformDirection(-ip.direction());
+  vec3d local_in = ct.inverseTransformDirection(light_dir);
+
+  // get brdf
+  std::unique_ptr<const brdf_base> brdf = make_brdf(ip.textureCoordinate());
+
+  // eval
+  return brdf->shade(local_in, local_out);
+}
+
+
+color reflectanceShader_base::reflectance(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  // create shading frame (note: in and out point away!)
+  coordinateTransformation ct = ip.shadingFrame();
+  vec3d local_out = ct.inverseTransformDirection(-ip.direction());
+  vec3d local_in = ct.inverseTransformDirection(light_dir);
+
+  // get brdf
+  std::unique_ptr<const brdf_base> brdf = make_brdf(ip.textureCoordinate());
+
+  // eval
+  return brdf->reflectance(local_in, local_out);
+}
+
+
+brdfSample reflectanceShader_base::sample(const intersectionPoint& ip, float r1, float r2) const
+{
+  // create shading frame (note: in and out point away!)
+  coordinateTransformation ct = ip.shadingFrame();
+  vec3d local_out = ct.inverseTransformDirection(-ip.direction());
+
+  // get brdf
+  std::unique_ptr<const brdf_base> brdf = make_brdf(ip.textureCoordinate());
+
+  // sample (local shading frame)
+  brdfSample sample = brdf->sample(local_out, r1, r2);
+
+  // transform back to global shading frame
+  return sample.transform(ct);
+}
+
+
+float reflectanceShader_base::reflectivity(const intersectionPoint& ip) const
+{
+  // get brdf
+  std::unique_ptr<const brdf_base> brdf = make_brdf(ip.textureCoordinate());
+
+  // get reflectivity
+  return brdf->reflectivity();
+}
+
+
+shaderProperties reflectanceShader_base::properties(const intersectionPoint& ip) const
+{
+  // get brdf
+  std::unique_ptr<const brdf_base> brdf = make_brdf(ip.textureCoordinate());
+
+  // get properties
+  return shaderProperties(brdf->isDiffuse(), brdf->isSpecular());
+}
+
+
+color reflectanceShader_base::emittance(const intersectionPoint& ip) const
+{
+  return color();
+}
diff --git a/hw6/src/rotation3d.cpp b/hw6/src/rotation3d.cpp
new file mode 100644
index 0000000..13fddd5
--- /dev/null
+++ b/hw6/src/rotation3d.cpp
@@ -0,0 +1,47 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "constants.h"
+#include "rotation3d.h"
+
+//////////////////
+// Constructors //
+//////////////////
+rotation3d::rotation3d(void) 
+  : transformation3d()
+{
+  // Do Nothing
+}
+
+
+rotation3d::rotation3d(float angle, const vec3d& axis) 
+  : transformation3d()
+{
+  vec3d norm_axis = normalize(axis);
+  float s = sin(angle * PI / 180.0f);
+  float c = cos(angle * PI / 180.0f);
+
+  _transformation(0,0) = c + ((norm_axis.x * norm_axis.x) * (1.0f - c));
+  _transformation(0,1) = -(norm_axis.z * s) + ((norm_axis.x * norm_axis.y) * (1.0f - c));
+  _transformation(0,2) = (norm_axis.y * s) + ((norm_axis.x * norm_axis.z) * (1.0f - c));
+  _transformation(1,0) = (norm_axis.z * s) + ((norm_axis.x * norm_axis.y) * (1.0f - c));
+  _transformation(1,1) = c + ((norm_axis.y * norm_axis.y) * (1.0f - c));
+  _transformation(1,2) = -(norm_axis.x * s) + ((norm_axis.y * norm_axis.z) * (1.0f - c));
+  _transformation(2,0) = -(norm_axis.y * s) + ((norm_axis.x * norm_axis.z) * (1.0f - c));
+  _transformation(2,1) = (norm_axis.x * s) + ((norm_axis.y * norm_axis.z) * (1.0f - c));
+  _transformation(2,2) = c + ((norm_axis.z * norm_axis.z) * (1.0f - c));
+
+  _inverseTransformation = transpose(_transformation);
+}
+
+
+rotation3d::rotation3d(const rotation3d& r) 
+  : transformation3d(r)
+{
+  // Do Nothing
+}
diff --git a/hw6/src/rotationX3d.cpp b/hw6/src/rotationX3d.cpp
new file mode 100644
index 0000000..4a53570
--- /dev/null
+++ b/hw6/src/rotationX3d.cpp
@@ -0,0 +1,42 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "constants.h"
+#include "rotationX3d.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+rotationX3d::rotationX3d(void) 
+  : transformation3d()
+{
+  // Do Nothing
+}
+
+
+rotationX3d::rotationX3d(float angle) 
+  : transformation3d()
+{
+  float s = sin(angle * PI / 180.0f);
+  float c = cos(angle * PI / 180.0f);
+
+  _transformation(1,1) = c;
+  _transformation(2,1) = s;
+  _transformation(1,2) = -s;
+  _transformation(2,2) = c;
+
+  _inverseTransformation = transpose(_transformation);
+}
+
+
+rotationX3d::rotationX3d(const rotationX3d& r) 
+  : transformation3d(r)
+{
+  // Do Nothing
+}
diff --git a/hw6/src/rotationY3d.cpp b/hw6/src/rotationY3d.cpp
new file mode 100644
index 0000000..9ecd572
--- /dev/null
+++ b/hw6/src/rotationY3d.cpp
@@ -0,0 +1,42 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "constants.h"
+#include "rotationY3d.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+rotationY3d::rotationY3d(void) 
+  : transformation3d()
+{
+  // Do Nothing
+}
+
+
+rotationY3d::rotationY3d(float angle) 
+  : transformation3d()
+{
+  float s = sin(angle * PI / 180.0f);
+  float c = cos(angle * PI / 180.0f);
+
+  _transformation(0,0) = c;
+  _transformation(2,0) = -s;
+  _transformation(0,2) = s;
+  _transformation(2,2) = c;
+
+  _inverseTransformation = transpose(_transformation);
+}
+
+
+rotationY3d::rotationY3d(const rotationY3d& r) 
+  : transformation3d(r)
+{
+  // Do Nothing
+}
diff --git a/hw6/src/rotationZ3d.cpp b/hw6/src/rotationZ3d.cpp
new file mode 100644
index 0000000..5c73a78
--- /dev/null
+++ b/hw6/src/rotationZ3d.cpp
@@ -0,0 +1,42 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "constants.h"
+#include "rotationZ3d.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+rotationZ3d::rotationZ3d(void) 
+  : transformation3d()
+{
+  // Do Nothing
+}
+
+
+rotationZ3d::rotationZ3d(float angle) 
+  : transformation3d()
+{
+  float s = sin(angle * PI / 180.0f);
+  float c = cos(angle * PI / 180.0f);
+
+  _transformation(0,0) = c;
+  _transformation(1,0) = s;
+  _transformation(0,1) = -s;
+  _transformation(1,1) = c;
+
+  _inverseTransformation = transpose(_transformation);
+}
+
+
+rotationZ3d::rotationZ3d(const rotationZ3d& r) 
+  : transformation3d(r)
+{
+  // Do Nothing
+}
diff --git a/hw6/src/scale3d.cpp b/hw6/src/scale3d.cpp
new file mode 100644
index 0000000..7124f12
--- /dev/null
+++ b/hw6/src/scale3d.cpp
@@ -0,0 +1,41 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "scale3d.h"
+
+//////////////////
+// Constructors //
+//////////////////
+scale3d::scale3d(void) : transformation3d()
+{
+  // Do Nothing
+}
+
+
+scale3d::scale3d(float uniformScale) : transformation3d()
+{
+  _transformation.setDiagonal(uniformScale);
+  _inverseTransformation.setDiagonal(1.0f / uniformScale);
+}
+
+
+scale3d::scale3d(float scaleX, float scaleY, float scaleZ) : transformation3d()
+{
+  _transformation(0,0) = scaleX;
+  _transformation(1,1) = scaleY;
+  _transformation(2,2) = scaleZ;
+
+  _inverseTransformation(0,0) = 1.0f / scaleX;
+  _inverseTransformation(1,1) = 1.0f / scaleY;
+  _inverseTransformation(2,2) = 1.0f / scaleZ;
+}
+
+scale3d::scale3d(const scale3d& s) : transformation3d(s)
+{
+  // Do Nothing
+}
diff --git a/hw6/src/scene.cpp b/hw6/src/scene.cpp
new file mode 100644
index 0000000..35e0fe4
--- /dev/null
+++ b/hw6/src/scene.cpp
@@ -0,0 +1,60 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "scene.h"
+#include "render_base.h"
+
+////////////////
+// Inspectors //
+////////////////
+const camera& scene::getCamera(void) const
+{ 
+  return _camera; 
+}
+
+
+const lightsource_base& scene::getLightsource(size_t idx) const
+{
+  assert(idx < _lightsources.size());
+  return *(_lightsources[idx]);
+}
+
+
+size_t scene::numberOfLightsources(void) const
+{
+  return _lightsources.size();
+}
+
+
+bool scene::hasEnvironmentMap(void) const
+{
+  return (_environmentMap != nullptr);
+}
+
+
+color scene::evaluateEnvironmentMap(const vec3d& direction) const
+{
+  assert(_environmentMap);
+  return (*_environmentMap)(direction);
+}
+
+
+/////////////
+// Methods //
+/////////////
+intersectionPoint scene::intersect(const ray& r) const
+{
+  return _sceneGraphRoot->intersect(r);
+}
+
+
+image scene::render(void) const
+{
+  return _renderEngine->render(*this);
+}
diff --git a/hw6/src/sceneGraphNode.cpp b/hw6/src/sceneGraphNode.cpp
new file mode 100644
index 0000000..1a0f600
--- /dev/null
+++ b/hw6/src/sceneGraphNode.cpp
@@ -0,0 +1,39 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <algorithm>
+#include "sceneGraphNode.h"
+
+//////////////////
+// Constructors //
+//////////////////
+sceneGraphNode::sceneGraphNode(void)
+  : boundedCompound()
+{
+  // Do nothing
+}
+
+sceneGraphNode::sceneGraphNode(const std::vector<std::shared_ptr<const boundedPrimitive>>& nodes, const transformation3d& transform, const std::shared_ptr<const shader_base>& shader)
+  : boundedCompound(transform, shader)
+{
+  // copy nodes
+  _nodes = nodes;
+
+  // init bounding box
+  initializeBoundingBox();
+}
+
+
+/////////////
+// Methods //
+/////////////
+const std::vector<std::shared_ptr<const boundedPrimitive>>& sceneGraphNode::compounds(void) const
+{
+  return _nodes;
+}
+
diff --git a/hw6/src/sceneIO.cpp b/hw6/src/sceneIO.cpp
new file mode 100644
index 0000000..59e586d
--- /dev/null
+++ b/hw6/src/sceneIO.cpp
@@ -0,0 +1,93 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "util.h"
+#include "scene.h"
+#include "raycasting.h"
+#include "sceneGraphNode.h"
+#include "linear_intersector.h"
+
+#include "sceneIO_xml.h"
+#include "sceneIO_core.h"
+#include "sceneIO_cache.h"
+#include "sceneIO_basis.h"
+#include "sceneIO_light.h"
+#include "sceneIO_texture.h"
+#include "sceneIO_geometry.h"
+#include "sceneIO_material.h"
+
+
+void importScene(const std::string& filename, scene& s)
+{
+  // get root
+  std::string rootDir = getDirectory(filename);
+
+  // open xml
+  XMLNode sceneNode(filename);
+
+  // check if valid scene node
+  if(!sceneNode.isValid())
+    errorMessage("Failed to find 'scene' in %s.", filename.c_str());
+
+  // create sceneGraphNode, texture, and shader cache
+  nodeCache<boundedPrimitive> shape_cache;
+  nodeCache<texture_base> texture_cache;
+  nodeCache<shader_base> shader_cache;
+
+  // init scene data
+  bool autoTuneCamera = false;
+  std::unique_ptr<const intersector_factory_base> intersector(new linear_intersector_factory());
+  s._renderEngine = std::unique_ptr<const render_base>(new raycasting());
+ 
+  // process sceneNode
+  for(XMLNode node = sceneNode.firstChild(); node.isValid(); node++)
+  {
+    // check for general node-types
+    if(importTexture(node, texture_cache, rootDir)) continue;
+    if(importMaterial(node, shader_cache, texture_cache, rootDir)) continue;
+    if(importGeometry(node, shape_cache, shader_cache, texture_cache, rootDir)) continue;
+
+    // check for scene-root specific nodes
+    std::string nodeName = node.name();
+    if(nodeName == "camera") autoTuneCamera = importCamera(node, s._camera);
+    else if(nodeName == "light") s._lightsources.push_back( importLight(node, shape_cache, shader_cache, texture_cache, rootDir) );
+    else if(nodeName == "environmentMap") importEnvironmentMap(node, texture_cache, rootDir, s._environmentMap);
+    else if(nodeName == "intersector") importIntersector(node, intersector);
+    else if(nodeName == "renderer") importRenderEngine(node, s._renderEngine);
+    else errorMessage("Unknown node in scene xml: '%s'", nodeName.c_str());
+  }
+
+  // initialize all node's intersectors
+  auto nodeList = shape_cache.allNodes();
+  for(auto itr=nodeList.begin(); itr != nodeList.end(); itr++)
+    static_cast<boundedCompound*>(itr->get())->initialize(*intersector);
+  nodeList.clear();
+
+  // add all unreferences nodes to the _sceneGraphRoot.
+  // Note: remove any node without a shader
+  decltype(nodeList) unusedNodes;
+  nodeList = shape_cache.unusedNodes();
+  while(!nodeList.empty())
+  {
+    auto bck = nodeList.back();
+    if(bck->hasShader()) unusedNodes.push_back(bck);
+    nodeList.pop_back();
+  }
+
+  // -> init + add
+  std::unique_ptr<boundedCompound> root(new sceneGraphNode( *(reinterpret_cast< std::vector<std::shared_ptr<const boundedPrimitive>>* >(&unusedNodes)) ));
+  root->initialize(*intersector);
+  s._sceneGraphRoot = std::unique_ptr<const boundedCompound>(root.release());
+
+  // Auto Tune Camera is requested
+  if(autoTuneCamera) 
+    s._camera.frameBoundingBox( s._sceneGraphRoot->boundingbox() );
+
+  // Done.
+}
+
diff --git a/hw6/src/sceneIO_basis.cpp b/hw6/src/sceneIO_basis.cpp
new file mode 100644
index 0000000..6f768b0
--- /dev/null
+++ b/hw6/src/sceneIO_basis.cpp
@@ -0,0 +1,100 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+
+#include "errorMessage.h"
+#include "sceneIO_core.h"
+#include "sceneIO_basis.h"
+#include "sceneIO_cache.h"
+#include "sceneIO_texture.h"
+#include "sceneIO_transformation3d.h"
+
+#include "raycasting.h"
+#include "pathtracing.h"
+#include "recursiveRaytracing.h"
+
+#include "bvh_intersector.h"
+#include "linear_intersector.h"
+
+#include "environmentMap.h"
+
+bool importCamera(const XMLNode& node, camera& cam)
+{
+  // sanity check
+  assert(node.name() == "camera");
+
+  // import camera
+  cam = camera( getVec3d(node, "eye", vec3d(0.0f, 0.0f, 0.0f)),
+		getVec3d(node, "view", vec3d(0.0f, 0.0f, -1.0f)),
+		getVec3d(node, "up", vec3d(0.0f, 1.0f, 0.0f)),
+		getFloat(node, "fov", 60),
+		getInteger(node, "width", 256),
+		getInteger(node, "height", 256) );
+
+  // Done.
+  return( getString(node, "auto", "false") == "true");
+}
+
+
+void importRenderEngine(const XMLNode& node, std::unique_ptr<const render_base>& renderer)
+{
+  // sanity check
+  assert(node.name() == "renderer");
+
+  // get render engine type
+  std::string type = getString(node, "type", "raycasting");
+
+  // create render type
+  if(type == "raycasting") renderer = std::unique_ptr<const render_base>( new raycasting() );
+  else if(type == "recursiveRaytracing") renderer = std::unique_ptr<const render_base>( new recursiveRaytracing( getInteger(node, "maxDepth", 1), getInteger(node, "samplesPerPixel", 1) ) );
+  else if(type == "pathtracing") renderer = std::unique_ptr<const render_base>( new pathtracing( getInteger(node, "samplesPerPixel", 1), getString(node, "directOnly", "false") == "true") );
+  else errorMessage("Unknown render engine type (%s)", type.c_str());
+
+  // Done.
+}
+
+
+void importIntersector(const XMLNode& node, std::unique_ptr<const intersector_factory_base>& intersector)
+{
+  // sanity check
+  assert(node.name() == "intersector");
+
+  // get intersector type
+  std::string type = getString(node, "type", "linear");
+
+  // create intersector
+  if(type == "linear") intersector = std::unique_ptr<const intersector_factory_base>( new linear_intersector_factory());
+  else if(type == "bvh") intersector = std::unique_ptr<const intersector_factory_base>( new bvh_intersector_factory());
+  else errorMessage("Unknown intersector type (%s)", type.c_str());
+
+  // Done.  
+}
+
+
+void importEnvironmentMap(const XMLNode& node, nodeCache<texture_base>& texture_cache, const std::string& rootDir, std::unique_ptr<const environmentMap>& map)
+{
+  // sanity check
+  assert(node.name() == "environmentMap");
+
+  // node properties
+  transformation3d transform;
+  std::shared_ptr<const texture_base> texture;
+
+  // check child nodes
+  for(XMLNode child=node.firstChild(); child.isValid(); child++)
+  {
+    std::string name = child.name();
+    if(name == "transformation") importTransformation(child, transform);
+    else if(name == "texture") texture = importTexture(child, texture_cache, rootDir);
+    else errorMessage("Unknown node (%s) in environmentMap.", name.c_str());
+  }
+
+  // Done.
+  map = std::unique_ptr<const environmentMap>(new environmentMap(texture, transform));
+}
diff --git a/hw6/src/sceneIO_core.cpp b/hw6/src/sceneIO_core.cpp
new file mode 100644
index 0000000..123287e
--- /dev/null
+++ b/hw6/src/sceneIO_core.cpp
@@ -0,0 +1,99 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <string>
+#include <cstdlib>
+
+#include "sceneIO_core.h"
+#include "errorMessage.h"
+
+color getColor(const XMLNode& node, const std::string& name, const color& default_value)
+{
+  std::string value = node.attribute(name);
+
+  // if defined, process..
+  if(value != "") 
+  {
+    color result;
+    int s = sscanf(value.c_str(), "%f %f %f", &result.r, &result.g, &result.b);
+
+    // check if only 1 value is given or 3.
+    if(s == 1) return color(result.r, result.r, result.r);
+    else if(s == 3) return result;
+    else errorMessage("Failed to parse color value (%s)", value.c_str());
+  }
+
+  // else return default
+  return default_value;
+}
+
+
+vec3d getVec3d(const XMLNode& node, const std::string& name, const vec3d& default_value)
+{
+  std::string value = node.attribute(name);
+
+  // if defined, process..
+  if(value != "") 
+  {
+    vec3d result;
+    int s = sscanf(value.c_str(), "%f %f %f", &result.x, &result.y, &result.z);
+
+    // check if only 1 value is given or 3.
+    if(s == 1) return vec3d(result.x, result.x, result.x);
+    else if(s == 3) return result;
+    else errorMessage("Failed to parse vec3d value (%s)", value.c_str());
+  }
+
+  // else return default
+  return default_value;
+}
+
+
+vec2d getVec2d(const XMLNode& node, const std::string& name, const vec2d& default_value)
+{
+  std::string value = node.attribute(name);
+
+  // if defined, process..
+  if(value != "") 
+  {
+    vec2d result;
+    int s = sscanf(value.c_str(), "%f %f", &result.x, &result.y);
+
+    // check if only 1 value is given or 2.
+    if(s == 1) return vec2d(result.x, result.x);
+    else if(s == 2) return result;
+    else errorMessage("Failed to parse vec2d value (%s)", value.c_str());
+  }
+
+  // else returnd default
+  return default_value;
+}
+
+
+std::string getString(const XMLNode& node, const std::string& name, const std::string& default_value)
+{
+  std::string value = node.attribute(name);
+  if(value != "") return std::string(value);
+  else return default_value;
+}
+
+
+float getFloat(const XMLNode& node, const std::string& name, float default_value)
+{
+  std::string value = node.attribute(name);
+if(value != "") return atof(value.c_str());
+  else return default_value;
+}
+
+
+unsigned int getInteger(const XMLNode& node, const std::string& name, unsigned int default_value)
+{
+  std::string value = node.attribute(name);
+if(value != "") return atoi(value.c_str());
+  else return default_value;
+}
diff --git a/hw6/src/sceneIO_geometry.cpp b/hw6/src/sceneIO_geometry.cpp
new file mode 100644
index 0000000..5fa4a5c
--- /dev/null
+++ b/hw6/src/sceneIO_geometry.cpp
@@ -0,0 +1,187 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <vector>
+#include <memory>
+#include <string>
+#include <cstdio>
+#include <cassert>
+
+#include "sceneIO_xml.h"
+#include "sceneIO_core.h"
+#include "sceneIO_cache.h"
+#include "sceneIO_geometry.h"
+#include "sceneIO_material.h"
+#include "sceneIO_transformation3d.h"
+
+#include "util.h"
+#include "vec2d.h"
+#include "vec3d.h"
+#include "triangle.h"
+#include "constants.h"
+#include "importOBJ.h"
+#include "errorMessage.h"
+#include "triangleMesh.h"
+#include "random_number.h"
+#include "sceneGraphNode.h"
+
+static void importTriangle(const XMLNode& node, std::vector<triangle>& triangle_list)
+{
+  // sanity check
+  assert(node.name() == "triangle" || node.name() == "polygon");
+
+  // allocate temp data
+   unsigned int idx=0;
+   vec3d v[3], n[3];
+   vec2d t[3];
+
+   // for each child node, parse all vertices
+   for(XMLNode child = node.firstChild(); child.isValid(); child++)
+   {
+     std::string name = child.name();
+     if(name == "vertex") 
+     {
+       v[idx] = getVec3d(child, "v", vec3d(+LARGE));
+       n[idx] = getVec3d(child, "n", vec3d(0.0f));
+       t[idx] = getVec2d(child, "t", vec2d(+LARGE));
+
+       // check if valid vertex
+       if(v[idx].x >= +LARGE || v[idx].y >= +LARGE || v[idx].z >= +LARGE)
+	 errorMessage("Invalid vertex in %s definition.", node.name().c_str());
+
+       // create triangle
+       if(idx == 2)
+       {
+	 // determine which attributes are defined on the triangle
+	 bool hasNormals = (n[0].squared_length() > +EPSILON) && (n[0].squared_length() > +EPSILON) && (n[0].squared_length() > +EPSILON);
+	 bool hasTextureCoord = (fabs(t[0].x) < +LARGE && fabs(t[0].y) < +LARGE) && (fabs(t[1].x) < +LARGE && fabs(t[1].y) < +LARGE) && (fabs(t[2].x) < +LARGE && fabs(t[2].y) < +LARGE);
+
+	 if(!hasNormals && !hasTextureCoord) triangle_list.push_back(triangle(v[0], v[1], v[2]));
+	 else if(hasNormals && !hasTextureCoord) triangle_list.push_back(triangle(v[0], v[1], v[2], n[0], n[1], n[2]));
+	 else if(!hasNormals && hasTextureCoord) triangle_list.push_back(triangle(v[0], v[1], v[2], t[0], t[1], t[2]));
+	 else triangle_list.push_back(triangle(v[0], v[1], v[2], n[0], n[1], n[2], t[0], t[1], t[2]));
+
+	 // cycle (to support polygons)
+	 v[1] = v[2];
+	 n[1] = n[2];
+	 t[1] = t[2];
+       }
+       else idx++;
+     }
+     else errorMessage("Unknown child element in %s node (%s).", node.name().c_str(), name.c_str());
+   }
+
+   // check if at least one full triangle was found
+   if(idx != 2)
+     errorMessage("%s requires at least 3 vertices.", node.name().c_str());
+
+   // Done.
+ }
+
+
+/////////////////////////////////////////////////////////////////
+static std::shared_ptr<boundedPrimitive> importTriangleMesh(const XMLNode& node, nodeCache<boundedPrimitive>& shape_cache, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.name() == "triangleMesh");
+
+  // allocate node properties
+  transformation3d transform;
+  std::shared_ptr<const shader_base> material;
+  std::vector<triangle> triangle_list;
+
+  // import OBJ triangles
+  std::string objname = getString(node, "filename");
+  if(objname != "")
+  {
+    std::string path = getDirectory(objname);
+    if(path == "") objname = rootDir + objname;
+    importOBJ(objname, triangle_list);
+  }
+
+  // check child nodes
+  for(XMLNode child = node.firstChild(); child.isValid(); child++)
+  {
+    std::string name = child.name();
+
+    // general child nodes
+    auto tempmat = importMaterial(child, shader_cache, texture_cache, rootDir);
+    if(tempmat) material = tempmat;
+
+    // specialized child nodes
+    else if(name == "transformation") importTransformation(child, transform);
+    else if(name == "triangle" || name == "polygon") importTriangle(child, triangle_list);
+    else errorMessage("Unknown child-node in triangleMesh (%s).", name.c_str());
+  }
+
+  // Done.
+  return std::shared_ptr<boundedPrimitive>(new triangleMesh(triangle_list, material, transform));
+}
+
+/////////////////////////////////////////////////////////////////
+
+static std::shared_ptr<boundedPrimitive> importSceneGraphNode(const XMLNode& node, nodeCache<boundedPrimitive>& shape_cache, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.name() == "sceneGraphNode");
+
+  // node properties
+  transformation3d transform;
+  std::shared_ptr<const shader_base> material;
+  std::vector<std::shared_ptr<const boundedPrimitive>> child_nodes;
+
+  // check child nodes
+  for(XMLNode child = node.firstChild(); child.isValid(); child++)
+  {
+    std::string name = child.name();   
+
+    // general child nodes
+    auto tempmat = importMaterial(child, shader_cache, texture_cache, rootDir);
+    auto shape = importGeometry(child, shape_cache, shader_cache, texture_cache, rootDir);
+
+    if(tempmat) material = tempmat;
+    else if(shape) child_nodes.push_back(shape);
+
+    // node specific children.
+    else if(name == "transformation") importTransformation(child, transform);
+    else errorMessage("Unknown child-node in sceneGraphNode (%s).", name.c_str());
+  }
+
+  // Done.
+  return std::shared_ptr<boundedPrimitive>(new sceneGraphNode(child_nodes, transform, material));
+}
+
+/////////////////////////////////////////////////////////////////
+std::shared_ptr<boundedPrimitive> importGeometry(const XMLNode& node, nodeCache<boundedPrimitive>& shape_cache, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // check if geometry type
+  if(node.name() != "sceneGraphNode" && node.name() != "triangleMesh") return std::shared_ptr<boundedPrimitive>(nullptr);
+
+  // check if reference
+  std::string ref = getString(node, "ref");
+  std::shared_ptr<boundedPrimitive> shape = shape_cache.get(ref);
+  if(shape) return shape;
+  else if(ref != "") errorMessage("Unknown %s name (%s).", node.name().c_str(), ref.c_str());
+
+  // generate default name & get id
+  char defaultname[32]; sprintf(defaultname, "noname-%u", random_int());
+  std::string id = getString(node, "id", defaultname);
+
+  if(shape_cache.get(id))
+    errorMessage("%s-node id is not unique (%s).", node.name().c_str(), id.c_str());
+
+  // process primitive based on type
+  if(node.name() == "sceneGraphNode") shape = importSceneGraphNode(node, shape_cache, shader_cache, texture_cache, rootDir);
+  else if(node.name() == "triangleMesh") shape = importTriangleMesh(node, shape_cache, shader_cache, texture_cache, rootDir);
+  
+  // update cache
+  if(id != "") shape_cache.add(id, shape);
+
+  // Done.
+  return shape;
+}
diff --git a/hw6/src/sceneIO_light.cpp b/hw6/src/sceneIO_light.cpp
new file mode 100644
index 0000000..d763970
--- /dev/null
+++ b/hw6/src/sceneIO_light.cpp
@@ -0,0 +1,131 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+
+#include "errorMessage.h"
+#include "random_number.h"
+
+#include "sceneIO_core.h"
+#include "sceneIO_basis.h"
+#include "sceneIO_light.h"
+#include "sceneIO_texture.h"
+#include "sceneIO_material.h"
+#include "sceneIO_geometry.h"
+
+#include "spotLightsource.h"
+#include "areaLightsource.h"
+#include "pointLightsource.h"
+#include "directionalLightsource.h"
+
+#include "lightsourceGeometry.h"
+
+static std::shared_ptr<const lightsource_base> importDirectionalLight(const XMLNode& node)
+{
+  // get properties
+  vec3d direction = getVec3d(node, "direction", vec3d(0.0f, 0.0f, 1.0f));
+  color power = getColor(node, "power", color(1.0f, 1.0f, 1.0f));
+                                
+  // Done.
+  return std::shared_ptr<const lightsource_base>( new directionalLightsource( direction, power));
+}
+
+
+static std::shared_ptr<const lightsource_base> importPointLight(const XMLNode& node)
+{
+  // get properties
+  vec3d position = getVec3d(node, "position", vec3d(0.0f, 0.0f, 0.0f));
+  color power = getColor(node, "power", color(1.0f, 1.0f, 1.0f));
+  vec3d attenuation = getVec3d(node, "attenuation", vec3d(0.0f, 0.0f, 1.0f));
+
+  // Done
+  return std::shared_ptr<const lightsource_base>( new pointLightsource(position, power, attenuation)); 
+}
+
+
+static std::shared_ptr<const lightsource_base> importSpotLight(const XMLNode& node)
+{
+  // Get properties
+  vec3d position = getVec3d(node, "position", vec3d(0.0f, 0.0f, 0.0f));
+  vec3d direction = getVec3d(node, "direction", vec3d(0.0f, 0.0f, 1.0f));
+  float cutoff = getFloat(node, "cutoff", 30.0f);
+  float sharpness = getFloat(node, "sharpness", 1.0f);
+  color power = getColor(node, "power", color(1.0f, 1.0f, 1.0f));
+  vec3d attenuation = getVec3d(node, "attenuation", vec3d(0.0f, 0.0f, 1.0f));
+
+  // Done.
+  return std::shared_ptr<const lightsource_base>(new spotLightsource( position, direction, cutoff, sharpness, power, attenuation ));
+}
+
+
+static std::shared_ptr<const lightsource_base> importAreaLight(const XMLNode& node, nodeCache<boundedPrimitive>& shape_cache, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // get properties
+  color power = getColor(node, "power", color(1.0f, 1.0f, 1.0f));
+  vec3d attenuation = getVec3d(node, "attenuation", vec3d(0.0f, 0.0f, 1.0f));
+
+  // node properties
+  std::shared_ptr<const shader_base> reflectanceMaterial;
+  std::shared_ptr<const boundedPrimitive> geometry;
+
+  // get children
+  for(XMLNode child = node.firstChild(); child.isValid(); child++)
+  {
+    std::string name = child.name();
+
+    // general child nodes
+    auto tempMat = importMaterial(child, shader_cache, texture_cache, rootDir);
+    auto tempGeom = importGeometry(child, shape_cache, shader_cache, texture_cache, rootDir);
+
+    // specific child nodes
+    if(tempMat) reflectanceMaterial = tempMat;
+    else if(tempGeom) geometry = tempGeom;
+    else errorMessage("Unknown child-node in areaLightsource (%s).", name.c_str());
+  }
+  
+  // produce warning if shader defined on the geometry
+  if(geometry && geometry->hasShader() && !reflectanceMaterial)
+    warningMessage("Any shader defined on the geometry are ignored in AreaLightsource. Define a reflectance material explicitely in AreaLightsource instead.");
+
+  // Create
+  // 1) light source
+  // 2) light source geometry
+  std::shared_ptr<const lightsource_base> ls( new areaLightsource(power, geometry, attenuation) );
+  std::shared_ptr<boundedPrimitive> lsShape( new lightsourceGeometry(geometry, ls, reflectanceMaterial) );
+
+  // Add lsShape to shape_cache
+  char id[32]; sprintf(id, "lightgeometry-%u", random_int());
+shape_cache.add(std::string(id), lsShape);
+
+  // Done.
+  return ls;
+}
+
+
+std::shared_ptr<const lightsource_base> importLight(const XMLNode& node, nodeCache<boundedPrimitive>& shape_cache, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.name() == "light");
+
+  // get light source type
+  std::string type = getString(node, "type", "directional");
+ 
+  // create light source
+  std::shared_ptr<const lightsource_base> ls;
+  if(type == "directional") ls = importDirectionalLight(node);
+  else if(type == "point") ls = importPointLight(node);
+  else if(type == "spot") ls = importSpotLight(node);
+  else if(type == "area") ls = importAreaLight(node, shape_cache, shader_cache, texture_cache, rootDir);
+  else errorMessage("Unknown light source type (%s)", type.c_str());
+
+  // Done.
+  return ls;
+}
+
+
+
diff --git a/hw6/src/sceneIO_material.cpp b/hw6/src/sceneIO_material.cpp
new file mode 100644
index 0000000..7999eca
--- /dev/null
+++ b/hw6/src/sceneIO_material.cpp
@@ -0,0 +1,243 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+
+#include "sceneIO_xml.h"
+#include "sceneIO_core.h"
+#include "sceneIO_texture.h"
+#include "sceneIO_material.h"
+
+#include "bumpMap.h"
+#include "normalMap.h"
+#include "compoundShader.h"
+#include "reflectanceParameter.h"
+#include "phongReflectanceShader.h"
+#include "diffuseReflectanceShader.h"
+
+//////////////////////////////////////////////////////////////
+static colorReflectanceParameter importColorReflectanceParameter(const XMLNode& node, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // get parameter
+  color value = getColor(node, "value", color(0.0f, 0.0f, 0.0f));
+  
+  // check for texture
+  std::shared_ptr<const texture_base> texture = importTexture(node.firstChild(), texture_cache, rootDir);
+
+  // create & return parameter, give preference to textured parameters
+  if(texture) return colorReflectanceParameter(texture);
+  else return colorReflectanceParameter(value);
+
+  // Done.
+}
+
+//////////////////////////////////////////////////////////////
+static scalarReflectanceParameter importScalarReflectanceParameter(const XMLNode& node, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // get parameters
+  float value = getFloat(node, "value", 0.0f);
+  unsigned int channel = getInteger(node, "channel", 0);
+
+  // check for texture
+  std::shared_ptr<const texture_base> texture = importTexture(node.firstChild(), texture_cache, rootDir);
+
+  // create & return parameter, give preference to textured parameters
+  if(texture) return scalarReflectanceParameter(texture, channel);
+  else return scalarReflectanceParameter(value);
+
+  // Done.
+}
+
+//////////////////////////////////////////////////////////////
+static std::shared_ptr<shader_base> importDiffuse(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.name() == "diffuse");
+
+  // parameter storage
+  colorReflectanceParameter albedo;
+
+  // check child nodes
+  for(XMLNode child=node.firstChild(); child.isValid(); child++)
+  {
+    std::string name = child.name();
+    if(name == "albedo") albedo = importColorReflectanceParameter(child, texture_cache, rootDir);
+    else errorMessage("Unknown parameter in diffuse-node (%s).", name.c_str());
+  }
+
+  // Done.
+  return std::shared_ptr<shader_base>(new diffuseReflectanceShader(albedo));
+}
+
+//////////////////////////////////////////////////////////////
+static std::shared_ptr<shader_base> importPhong(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.name() == "phong");
+
+  // parameter storage
+  colorReflectanceParameter albedo;
+  scalarReflectanceParameter sharpness;
+
+  // check child nodes
+  for(XMLNode child=node.firstChild(); child.isValid(); child++)
+  {
+    std::string name = child.name();
+    if(name == "albedo") albedo = importColorReflectanceParameter(child, texture_cache, rootDir);
+    else if(name == "sharpness") sharpness = importScalarReflectanceParameter(child, texture_cache, rootDir);
+    else errorMessage("Unknown parameter in phong-node (%s).", name.c_str());
+  }
+
+  // Done.
+  return std::shared_ptr<shader_base>(new phongReflectanceShader(albedo, sharpness));
+}
+
+//////////////////////////////////////////////////////////////
+static std::shared_ptr<shader_base> importCompoundMaterial(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.isValid() && node.name() == "material");
+
+  // storage for child material nodes
+  std::vector<std::shared_ptr<const shader_base>> shader_list;
+
+  // for each child
+  for(XMLNode child = node.firstChild(); child.isValid(); child++)
+  {
+    // try to import material
+    std::shared_ptr<shader_base> shader = importMaterial(child, shader_cache, texture_cache, rootDir);
+
+    // add to list if successful.
+    if(shader) shader_list.push_back(shader);
+    else errorMessage("Unknown material-node (%s).", child.name().c_str());
+  }
+
+  // Done.
+  return std::shared_ptr<shader_base>(new compoundShader(shader_list));
+}
+
+//////////////////////////////////////////////////////////////
+std::shared_ptr<shader_base> importNormalMap(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(getString(node, "type") == "normalMap");
+
+  // parameter storage
+  std::shared_ptr<const shader_base> shader;
+  std::shared_ptr<const texture_base> map;
+
+  // process child nodes
+  for(XMLNode child=node.firstChild(); child.isValid(); child++)
+  {
+    // process specific nodes
+    if(child.name() == "texture") map = importTexture(child, texture_cache, rootDir);
+
+    // process general shader nodes
+    else if(!shader) shader = importMaterial(child, shader_cache, texture_cache, rootDir);
+
+    else if(!shader) errorMessage("Unknown node in normalMap (%s).", child.name().c_str());
+  }
+
+  // check if shader & texture was specified
+  if(!shader) errorMessage("NormalMap requires a shader.");
+  if(!map) errorMessage("NormalMap requires a texture.");
+
+  // Done.
+  return std::shared_ptr<shader_base>(new normalMap(map, shader));
+}
+
+//////////////////////////////////////////////////////////////
+std::shared_ptr<shader_base> importBumpMap(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(getString(node, "type") == "bumpMap");
+
+  // obtain parameters
+  float scale = getFloat(node, "scale", 1.0f);
+  unsigned int channel = getInteger(node, "channel", 0);
+
+  // parameter storage
+  std::shared_ptr<const shader_base> shader;
+  std::shared_ptr<const texture_base> map;
+
+  // process child nodes
+  for(XMLNode child=node.firstChild(); child.isValid(); child++)
+  {
+    // process specific nodes
+    if(child.name() == "texture") map = importTexture(child, texture_cache, rootDir);
+
+    // process general shader nodes
+    else if(!shader) shader = importMaterial(child, shader_cache, texture_cache, rootDir);
+
+    else if(!shader) errorMessage("Unknown node in bumpMap (%s).", child.name().c_str());
+  }
+
+  // check if shader & texture was specified
+  if(!shader) errorMessage("BumpMap requires a shader.");
+  if(!map) errorMessage("BumpMap requires a texture.");
+
+  // Done.
+  return std::shared_ptr<shader_base>(new bumpMap(map, scale, channel, shader));
+}
+
+//////////////////////////////////////////////////////////////
+std::shared_ptr<shader_base> importShadingFrameTransformation(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // sanity check
+  assert(node.name() == "shadingFrameTransformation");
+
+  // get type
+  std::string type = getString(node, "type", "none specified");
+  
+  // specialize based on type
+  std::shared_ptr<shader_base> sft;
+
+  if(type == "normalMap") sft = importNormalMap(node, shader_cache, texture_cache, rootDir);
+  else if(type == "bumpMap") sft = importBumpMap(node, shader_cache, texture_cache, rootDir);
+  else errorMessage("Unknown shadingFrameTransformation type (%s).", type.c_str());
+
+  // Done.
+  return sft;
+}
+
+//////////////////////////////////////////////////////////////
+std::shared_ptr<shader_base> importMaterial(const XMLNode& node, nodeCache<shader_base>& shader_cache, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  std::string name = node.name();
+
+  // check material type
+  if(name != "material" &&
+     name != "shadingFrameTransformation" &&
+     name != "diffuse" &&
+     name != "phong") return std::shared_ptr<shader_base>(nullptr);
+
+  // check if reference
+  std::string ref = getString(node, "ref");
+  std::shared_ptr<shader_base> shader = shader_cache.get(ref);
+  if(shader) return shader;
+  else if(ref != "") errorMessage("Unknown %s name (%s).", name.c_str(), ref.c_str());
+ 
+  // get id
+  std::string id = getString(node, "id");
+  if(shader_cache.get(id))
+    errorMessage("%s-id is not unique (%s).", name.c_str(), id.c_str());
+
+  // process primitives based on type
+  if(name == "material") shader = importCompoundMaterial(node, shader_cache, texture_cache, rootDir);
+  else if(name == "shadingFrameTransformation") shader = importShadingFrameTransformation(node, shader_cache, texture_cache, rootDir);
+  else if(name == "diffuse") shader = importDiffuse(node, shader_cache, texture_cache, rootDir);
+  else if(name == "phong") shader = importPhong(node, shader_cache, texture_cache, rootDir);
+  else errorMessage("Unknown material-node (%s).", name.c_str());
+
+  // update cache
+  if(id != "") shader_cache.add(id, shader);
+
+  // Done.
+  return shader;
+}
+
diff --git a/hw6/src/sceneIO_texture.cpp b/hw6/src/sceneIO_texture.cpp
new file mode 100644
index 0000000..f537613
--- /dev/null
+++ b/hw6/src/sceneIO_texture.cpp
@@ -0,0 +1,55 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "sceneIO_core.h"
+#include "sceneIO_texture.h"
+
+#include "util.h"
+#include "imageIO.h"
+#include "nearestTexture.h"
+#include "bilinearTexture.h"
+
+std::shared_ptr<texture_base> importTexture(const XMLNode& node, nodeCache<texture_base>& texture_cache, const std::string& rootDir)
+{
+  // check if texture
+  if(!node.isValid() || node.name() != "texture") return std::shared_ptr<texture_base>(nullptr);
+
+  // get attributes
+  std::string type = getString(node, "type", "nearest");
+  std::string filename = getString(node, "filename");
+  bool repeatTexture = (getString(node, "repeatTexture", "false") == "false");
+
+  // sanity check
+  if(filename == "")
+    errorMessage("Missing texture 'filename'.");
+
+  // get full filename
+  std::string path = getDirectory(filename);
+  if(path == "") filename = rootDir + filename;
+
+  // get key name
+  std::string key = filename + "#" + type;
+  if(repeatTexture) key += "Repeat";
+
+  // check cache
+  if(std::shared_ptr<texture_base> ctexture = texture_cache.get(key))
+    return ctexture;
+
+  // create based on type
+  std::shared_ptr<texture_base> texture;
+  if(type == "nearest") texture = std::shared_ptr<texture_base>( new nearestTexture(repeatTexture));
+  else if(type == "bilinear") texture = std::shared_ptr<texture_base>( new bilinearTexture(repeatTexture) );
+  else errorMessage("Unknown texture type (%s).", type.c_str());
+
+  // load and add texture to cache
+  importImage(filename, *texture);
+  texture_cache.add(key, texture);
+
+  // Done.
+  return texture;
+}
diff --git a/hw6/src/sceneIO_transformation3d.cpp b/hw6/src/sceneIO_transformation3d.cpp
new file mode 100644
index 0000000..cf54449
--- /dev/null
+++ b/hw6/src/sceneIO_transformation3d.cpp
@@ -0,0 +1,80 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "sceneIO_core.h"
+#include "sceneIO_transformation3d.h"
+
+#include "rotationX3d.h"
+#include "rotationY3d.h"
+#include "rotationZ3d.h"
+#include "rotation3d.h"
+#include "translation3d.h"
+#include "scale3d.h"
+
+#include "errorMessage.h"
+
+static transformation3d importRotationX(const XMLNode& node)
+{
+  return rotationX3d(getFloat(node, "angle", 0.0f));
+}
+
+static transformation3d importRotationY(const XMLNode& node)
+{
+  return rotationY3d(getFloat(node, "angle", 0.0f));
+}
+
+static transformation3d importRotationZ(const XMLNode& node)
+{
+  return rotationZ3d(getFloat(node, "angle", 0.0f));
+}
+
+static transformation3d importRotationAxis(const XMLNode& node)
+{
+  return rotation3d(getFloat(node, "angle", 0.0f), 
+                    getVec3d(node, "axis", vec3d(0.0f, 0.0f, 1.0f)));
+}
+
+static transformation3d importTranslation(const XMLNode& node)
+{
+  return translation3d(getVec3d(node, "offset", vec3d(0.0f)));
+}
+
+static transformation3d importScale(const XMLNode& node)
+{
+  vec3d scale = getVec3d(node, "scale", vec3d(1.0f));
+  return scale3d(scale.x, scale.y, scale.z);
+}
+
+
+
+void importTransformation(const XMLNode& node, transformation3d& transform)
+{
+  // sanity check
+  assert(node.name() == "transformation");
+
+  // accumulate all child nodes
+  for(XMLNode childNode = node.firstChild(); childNode.isValid(); childNode++)
+  {
+    // get transformation type:
+    std::string type = childNode.name();
+
+    // parse
+    if(type == "rotationX") transform *= importRotationX(childNode);
+    else if(type == "rotationY") transform *= importRotationY(childNode);
+    else if(type == "rotationZ") transform *= importRotationZ(childNode);
+    else if(type == "rotation") transform *= importRotationAxis(childNode);
+    else if(type == "translation") transform *= importTranslation(childNode);
+    else if(type == "scale") transform *= importScale(childNode);
+    else errorMessage("Unknown transformation (%s)", type.c_str());
+  }
+
+  // Done.
+}
+
+
diff --git a/hw6/src/sceneIO_xml.cpp b/hw6/src/sceneIO_xml.cpp
new file mode 100644
index 0000000..47aa94e
--- /dev/null
+++ b/hw6/src/sceneIO_xml.cpp
@@ -0,0 +1,112 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cassert>
+#include "sceneIO_xml.h"
+#include "errorMessage.h"
+
+/////////////////
+// Constructor //
+/////////////////
+XMLNode::XMLNode(const std::string& filename)
+{
+  // open xml
+  _xml = std::make_shared<tinyxml2::XMLDocument>();
+  _xml->LoadFile(filename.c_str());
+
+  // check if open successful
+  if(_xml->ErrorID() != tinyxml2::XML_SUCCESS)
+    errorMessage("Failed to open scene file: '%s'.", filename.c_str());
+
+  // set first node.
+  _element = _xml->FirstChildElement("scene");
+}
+
+
+XMLNode::XMLNode(const XMLNode& node)
+{
+  _element = node._element;
+  _xml = node._xml;
+}
+
+XMLNode::XMLNode(const tinyxml2::XMLElement* element, const std::shared_ptr<tinyxml2::XMLDocument>& xml)
+{
+  _element = element;
+  _xml = xml;
+}
+
+
+/////////////
+// Methods //
+/////////////
+XMLNode XMLNode::firstChild(void) const
+{
+  assert(isValid());
+  return XMLNode(_element->FirstChildElement(), _xml);
+}
+ 
+
+XMLNode XMLNode::findChild(const std::string& name) const
+{
+  assert(isValid());
+  return XMLNode(_element->FirstChildElement(name.c_str()), _xml);
+}
+ 
+ 
+bool XMLNode::isValid(void) const
+{
+  return (_element != NULL);
+}
+
+
+std::string XMLNode::name(void) const
+{
+  assert(isValid());
+  return std::string(_element->Name());
+}
+
+
+std::string XMLNode::attribute(const std::string& attribute) const
+{
+  assert(isValid());
+
+  const char* str = _element->Attribute(attribute.c_str());
+  if(str == NULL) return std::string("");
+
+  // Done.
+  return std::string(str);
+}
+
+
+///////////////
+// Operators //
+///////////////
+XMLNode& XMLNode::operator=(const XMLNode& src)
+{
+  _element = src._element;
+  _xml = src._xml;
+  return *this;
+}
+
+
+XMLNode& XMLNode::operator++(int)
+{
+  assert(_element != NULL);
+  _element = _element->NextSiblingElement();
+  return *this;
+}
+
+
+XMLNode& XMLNode::operator++(void)
+{
+  assert(_element != NULL);
+  _element = _element->NextSiblingElement();
+  return *this;
+}
+
+
diff --git a/hw6/src/shaderProperties.cpp b/hw6/src/shaderProperties.cpp
new file mode 100644
index 0000000..235e73d
--- /dev/null
+++ b/hw6/src/shaderProperties.cpp
@@ -0,0 +1,62 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "shaderProperties.h"
+
+
+//////////////
+// Operator //
+//////////////
+bool shaderProperties::operator==(const shaderProperties& sp) const
+{
+  return (diffuse == sp.diffuse) && (specular == sp.specular);
+}
+
+
+bool shaderProperties::operator!=(const shaderProperties& sp) const
+{
+  return !(*this == sp);
+}
+
+
+shaderProperties& shaderProperties::operator&=(const shaderProperties& sp)
+{
+  diffuse &= sp.diffuse;
+  specular &= sp.specular;
+  return *this;
+}
+
+
+shaderProperties& shaderProperties::operator|=(const shaderProperties& sp)
+{
+  diffuse |= sp.diffuse;
+  specular |= sp.specular;
+  return *this;
+}
+
+
+shaderProperties& shaderProperties::operator~(void)
+{
+  diffuse = ~diffuse;
+  specular = ~specular;
+  return *this;
+}
+
+
+shaderProperties shaderProperties::operator&(const shaderProperties& sp) const
+{
+  return shaderProperties(diffuse & sp.diffuse,
+			  specular & sp.specular);
+}
+
+
+shaderProperties shaderProperties::operator|(const shaderProperties& sp) const
+{
+  return shaderProperties(diffuse | sp.diffuse,
+			  specular | sp.specular);
+}
diff --git a/hw6/src/shadingFrameTransformation.cpp b/hw6/src/shadingFrameTransformation.cpp
new file mode 100644
index 0000000..8dfb589
--- /dev/null
+++ b/hw6/src/shadingFrameTransformation.cpp
@@ -0,0 +1,82 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "shadingFrameTransformation.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+shadingFrameTransformation::shadingFrameTransformation(const std::shared_ptr<const shader_base>& shader)
+  : shader_base()
+{
+  _shader = shader;
+}
+
+
+/////////////
+// Methods //
+/////////////
+color shadingFrameTransformation::shade(const intersectionPoint& ip, const vec3d& light_dir) const 
+{
+  // transform to local shading frame
+  intersectionPoint localIp(ip);
+  localIp.inverseTransformShadingFrame( _transformation(ip.textureCoordinate()) );
+
+  // Done.
+  return _shader->shade(localIp, light_dir);
+}
+
+
+color shadingFrameTransformation::reflectance(const intersectionPoint& ip, const vec3d& light_dir) const
+{
+  // transform to local shading frame
+  intersectionPoint localIp(ip);
+  localIp.inverseTransformShadingFrame( _transformation(ip.textureCoordinate()) );
+
+  // Done.
+  return _shader->reflectance(localIp, light_dir);
+}
+
+
+brdfSample shadingFrameTransformation::sample(const intersectionPoint& ip, float r1, float r2) const
+{
+  // transform to local shading frame
+  intersectionPoint localIp(ip);
+  transformation3d ct = _transformation(ip.textureCoordinate());
+  localIp.inverseTransformShadingFrame(ct);
+
+  //get sample (in local shading frame)
+  brdfSample sample = _shader->sample(localIp, r1, r2);
+
+  // transform to global shading frame
+  return sample.transform(ct);
+}
+
+
+float shadingFrameTransformation::reflectivity(const intersectionPoint& ip) const
+{
+  return _shader->reflectivity(ip);
+}
+
+
+color shadingFrameTransformation::emittance(const intersectionPoint& ip) const
+{
+  // transform to local shading frame
+  intersectionPoint localIp(ip);
+  localIp.inverseTransformShadingFrame( _transformation(ip.textureCoordinate()) );
+
+  // Done.
+  return _shader->emittance(localIp);
+}
+
+
+shaderProperties shadingFrameTransformation::properties(const intersectionPoint& ip) const
+{
+  return _shader->properties(ip);
+}
diff --git a/hw6/src/spotLightsource.cpp b/hw6/src/spotLightsource.cpp
new file mode 100644
index 0000000..9b4d0ab
--- /dev/null
+++ b/hw6/src/spotLightsource.cpp
@@ -0,0 +1,69 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "constants.h"
+#include "spotLightsource.h"
+
+//////////////////
+// Constructors //
+//////////////////
+spotLightsource::spotLightsource(const vec3d& position, const vec3d& direction, float cutoffDegrees, float sharpness, const color& power, const vec3d& attenuation)
+{
+  _position = position;
+  _direction = normalize(direction);
+  _cutoff = cos(cutoffDegrees * PI / 180.0f);
+  _sharpness = sharpness;
+  _power = power;
+  _attenuation = attenuation;
+}
+
+
+/////////////
+// Methods //
+/////////////
+lightSample spotLightsource::intensityAt(const vec3d& point) const
+{
+  vec3d direction = point - _position;
+  float distance = direction.length();
+  float cosAngle = _direction.dot(direction) / distance;
+
+  // check if outside cone
+  if(cosAngle < _cutoff) return lightSample(direction, color(0.0f, 0.0f, 0.0f), distance);
+
+  // compute attenuation & scale
+  float attenuation = ((_attenuation[2]*distance + _attenuation[1])*distance + _attenuation[0]);
+  float scale = pow(cosAngle, _sharpness);
+
+  // Done.
+  return lightSample(direction, _power * scale / attenuation, distance);
+}
+
+
+lightSample spotLightsource::emittanceAt(const vec3d& point, float r1, float r2) const
+{
+  vec3d direction = point - _position;
+  float distance = direction.length();
+  float cosAngle = _direction.dot(direction) / distance;
+
+  // compute emittance
+  color emittance = (cosAngle < _cutoff) ? color(0.0f, 0.0f, 0.0f) : _power * pow(cosAngle, _sharpness) / (4.0f * PI);
+
+  // Done.
+  // PDF = 1.0 => there is only a single point
+  // Foreshortening => no normal
+  return lightSample(direction, emittance, distance, 1.0f, 1.0f);
+}
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void spotLightsource::_print(std::ostream& s) const
+{
+  s << "Spot Lightsource: position=" << _position << ", direction=" << _direction << ", cutoff=" << (acos(_cutoff)*180.0f/PI) << ", sharpness=" << _sharpness << ", power=" << _power << ", attenuation=" << _attenuation;  
+}
diff --git a/hw6/src/surfaceSample.cpp b/hw6/src/surfaceSample.cpp
new file mode 100644
index 0000000..464c969
--- /dev/null
+++ b/hw6/src/surfaceSample.cpp
@@ -0,0 +1,118 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <cmath>
+#include "surfaceSample.h"
+
+//////////////////
+// Constructors //
+//////////////////
+surfaceSample::surfaceSample(void)
+{
+  _position = vec3d();
+  _normal = vec3d();
+  _pdf = 0.0f;
+}
+
+
+surfaceSample::surfaceSample(const vec3d& position, const vec3d& normal, const float pdf)
+{
+  _position = position;
+  _normal = normal;
+  _pdf = std::max(pdf, 0.0f);
+}
+
+
+surfaceSample::surfaceSample(const surfaceSample& ss)
+{
+  _position = ss._position;
+  _normal = ss._normal;
+  _pdf = ss._pdf;
+}
+
+
+///////////////
+// Operators //
+///////////////
+surfaceSample& surfaceSample::operator=(const surfaceSample& ss)
+{
+  _assign(ss);
+  return *this;
+}
+  
+
+surfaceSample surfaceSample::operator*(float pdf) const
+{
+  return surfaceSample(_position, _normal, _pdf * pdf);
+}
+
+
+surfaceSample& surfaceSample::operator*=(float pdf)
+{
+  _pdf *= pdf;
+  return *this;
+}
+
+
+////////////////
+// Inspectors //
+////////////////
+const vec3d& surfaceSample::position(void) const
+{
+  return _position;
+}
+
+
+const vec3d& surfaceSample::normal(void) const
+{
+  return _normal;
+}
+
+
+float surfaceSample::pdf(void) const
+{
+  return _pdf;
+}
+
+
+/////////////
+// Methods //
+/////////////
+surfaceSample& surfaceSample::transform(const transformation3d& t)
+{
+  _position = t.transformPoint(_position);
+  _normal = t.transformNormal(_normal);
+  return *this;
+}
+
+
+surfaceSample& surfaceSample::inverseTransform(const transformation3d& t)
+{
+  _position = t.inverseTransformPoint(_position);
+  _normal = t.inverseTransformNormal(_normal);
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void surfaceSample::_swap(surfaceSample& s)
+{
+  swap(_position, s._position);
+  swap(_normal, s._normal);
+  std::swap(_pdf, s._pdf);
+}
+
+
+void surfaceSample::_assign(const surfaceSample& s)
+{
+  _position = s._position;
+  _normal = s._normal;
+  _pdf = s._pdf;
+}
diff --git a/hw6/src/texture_base.cpp b/hw6/src/texture_base.cpp
new file mode 100644
index 0000000..2a90146
--- /dev/null
+++ b/hw6/src/texture_base.cpp
@@ -0,0 +1,95 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "texture_base.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+texture_base::texture_base(bool repeat)
+  : image()
+{
+  _repeat = repeat;
+}
+
+texture_base::texture_base(const texture_base& src)
+  : image(src)
+{
+  _repeat = src._repeat;
+}
+
+
+///////////////
+// Operators //
+///////////////
+texture_base& texture_base::operator=(const texture_base& src)
+{
+  _assign(src);
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void texture_base::_assign(const texture_base& src)
+{
+  image::_assign(src);
+  _repeat = src._repeat;
+}
+
+
+static void repeatCoordinate(signed int& p, signed int maxCoord)
+{
+  if(p < 0) p = 0;
+  else if(p >= maxCoord) p = maxCoord-1;
+}
+
+static void wrapCoordinate(signed int& p, signed int maxCoord)
+{
+  if(p < 0) p = (maxCoord  + (p % maxCoord)) % maxCoord;
+  else if(p >= maxCoord) p %= maxCoord;
+}
+
+color& texture_base::_at(signed int x, signed int y)
+{
+  // repeat
+  if(_repeat) 
+  {
+    repeatCoordinate(x, width());
+    repeatCoordinate(y, height());
+  }
+  // wrap
+  else {
+    wrapCoordinate(x, width());
+    wrapCoordinate(y, height());
+  }
+
+  // get value
+  return image::operator()(x,y);
+}
+
+
+const color& texture_base::_at(signed int x, signed int y) const
+{
+  // repeat
+  if(_repeat) 
+  {
+    repeatCoordinate(x, width());
+    repeatCoordinate(y, height());
+  }
+  // wrap
+  else {
+    wrapCoordinate(x, width());
+    wrapCoordinate(y, height());
+  }
+
+  // get value
+  return image::operator()(x,y);
+}
diff --git a/hw6/src/tinyxml2.cpp b/hw6/src/tinyxml2.cpp
new file mode 100644
index 0000000..0c903fe
--- /dev/null
+++ b/hw6/src/tinyxml2.cpp
@@ -0,0 +1,2794 @@
+/*

+Original code by Lee Thomason (www.grinninglizard.com)

+

+This software is provided 'as-is', without any express or implied

+warranty. In no event will the authors be held liable for any

+damages arising from the use of this software.

+

+Permission is granted to anyone to use this software for any

+purpose, including commercial applications, and to alter it and

+redistribute it freely, subject to the following restrictions:

+

+1. The origin of this software must not be misrepresented; you must

+not claim that you wrote the original software. If you use this

+software in a product, an acknowledgment in the product documentation

+would be appreciated but is not required.

+

+2. Altered source versions must be plainly marked as such, and

+must not be misrepresented as being the original software.

+

+3. This notice may not be removed or altered from any source

+distribution.

+*/

+

+#include "tinyxml2.h"

+

+#include <new>		// yes, this one new style header, is in the Android SDK.

+#if defined(ANDROID_NDK) || defined(__BORLANDC__) || defined(__QNXNTO__)

+#   include <stddef.h>

+#   include <stdarg.h>

+#else

+#   include <cstddef>

+#   include <cstdarg>

+#endif

+

+#if defined(_MSC_VER) && (_MSC_VER >= 1400 ) && (!defined WINCE)

+	// Microsoft Visual Studio, version 2005 and higher. Not WinCE.

+	/*int _snprintf_s(

+	   char *buffer,

+	   size_t sizeOfBuffer,

+	   size_t count,

+	   const char *format [,

+		  argument] ...

+	);*/

+	static inline int TIXML_SNPRINTF( char* buffer, size_t size, const char* format, ... )

+	{

+		va_list va;

+		va_start( va, format );

+		int result = vsnprintf_s( buffer, size, _TRUNCATE, format, va );

+		va_end( va );

+		return result;

+	}

+

+	static inline int TIXML_VSNPRINTF( char* buffer, size_t size, const char* format, va_list va )

+	{

+		int result = vsnprintf_s( buffer, size, _TRUNCATE, format, va );

+		return result;

+	}

+

+	#define TIXML_VSCPRINTF	_vscprintf

+	#define TIXML_SSCANF	sscanf_s

+#elif defined _MSC_VER

+	// Microsoft Visual Studio 2003 and earlier or WinCE

+	#define TIXML_SNPRINTF	_snprintf

+	#define TIXML_VSNPRINTF _vsnprintf

+	#define TIXML_SSCANF	sscanf

+	#if (_MSC_VER < 1400 ) && (!defined WINCE)

+		// Microsoft Visual Studio 2003 and not WinCE.

+		#define TIXML_VSCPRINTF   _vscprintf // VS2003's C runtime has this, but VC6 C runtime or WinCE SDK doesn't have.

+	#else

+		// Microsoft Visual Studio 2003 and earlier or WinCE.

+		static inline int TIXML_VSCPRINTF( const char* format, va_list va )

+		{

+			int len = 512;

+			for (;;) {

+				len = len*2;

+				char* str = new char[len]();

+				const int required = _vsnprintf(str, len, format, va);

+				delete[] str;

+				if ( required != -1 ) {

+					TIXMLASSERT( required >= 0 );

+					len = required;

+					break;

+				}

+			}

+			TIXMLASSERT( len >= 0 );

+			return len;

+		}

+	#endif

+#else

+	// GCC version 3 and higher

+	//#warning( "Using sn* functions." )

+	#define TIXML_SNPRINTF	snprintf

+	#define TIXML_VSNPRINTF	vsnprintf

+	static inline int TIXML_VSCPRINTF( const char* format, va_list va )

+	{

+		int len = vsnprintf( 0, 0, format, va );

+		TIXMLASSERT( len >= 0 );

+		return len;

+	}

+	#define TIXML_SSCANF   sscanf

+#endif

+

+

+static const char LINE_FEED				= (char)0x0a;			// all line endings are normalized to LF

+static const char LF = LINE_FEED;

+static const char CARRIAGE_RETURN		= (char)0x0d;			// CR gets filtered out

+static const char CR = CARRIAGE_RETURN;

+static const char SINGLE_QUOTE			= '\'';

+static const char DOUBLE_QUOTE			= '\"';

+

+// Bunch of unicode info at:

+//		http://www.unicode.org/faq/utf_bom.html

+//	ef bb bf (Microsoft "lead bytes") - designates UTF-8

+

+static const unsigned char TIXML_UTF_LEAD_0 = 0xefU;

+static const unsigned char TIXML_UTF_LEAD_1 = 0xbbU;

+static const unsigned char TIXML_UTF_LEAD_2 = 0xbfU;

+

+namespace tinyxml2

+{

+

+struct Entity {

+    const char* pattern;

+    int length;

+    char value;

+};

+

+static const int NUM_ENTITIES = 5;

+static const Entity entities[NUM_ENTITIES] = {

+    { "quot", 4,	DOUBLE_QUOTE },

+    { "amp", 3,		'&'  },

+    { "apos", 4,	SINGLE_QUOTE },

+    { "lt",	2, 		'<'	 },

+    { "gt",	2,		'>'	 }

+};

+

+

+StrPair::~StrPair()

+{

+    Reset();

+}

+

+

+void StrPair::TransferTo( StrPair* other )

+{

+    if ( this == other ) {

+        return;

+    }

+    // This in effect implements the assignment operator by "moving"

+    // ownership (as in auto_ptr).

+

+    TIXMLASSERT( other != 0 );

+    TIXMLASSERT( other->_flags == 0 );

+    TIXMLASSERT( other->_start == 0 );

+    TIXMLASSERT( other->_end == 0 );

+

+    other->Reset();

+

+    other->_flags = _flags;

+    other->_start = _start;

+    other->_end = _end;

+

+    _flags = 0;

+    _start = 0;

+    _end = 0;

+}

+

+

+void StrPair::Reset()

+{

+    if ( _flags & NEEDS_DELETE ) {

+        delete [] _start;

+    }

+    _flags = 0;

+    _start = 0;

+    _end = 0;

+}

+

+

+void StrPair::SetStr( const char* str, int flags )

+{

+    TIXMLASSERT( str );

+    Reset();

+    size_t len = strlen( str );

+    TIXMLASSERT( _start == 0 );

+    _start = new char[ len+1 ];

+    memcpy( _start, str, len+1 );

+    _end = _start + len;

+    _flags = flags | NEEDS_DELETE;

+}

+

+

+char* StrPair::ParseText( char* p, const char* endTag, int strFlags, int* curLineNumPtr )

+{

+    TIXMLASSERT( p );

+    TIXMLASSERT( endTag && *endTag );

+	TIXMLASSERT(curLineNumPtr);

+

+    char* start = p;

+    char  endChar = *endTag;

+    size_t length = strlen( endTag );

+

+    // Inner loop of text parsing.

+    while ( *p ) {

+        if ( *p == endChar && strncmp( p, endTag, length ) == 0 ) {

+            Set( start, p, strFlags );

+            return p + length;

+        } else if (*p == '\n') {

+            ++(*curLineNumPtr);

+        }

+        ++p;

+        TIXMLASSERT( p );

+    }

+    return 0;

+}

+

+

+char* StrPair::ParseName( char* p )

+{

+    if ( !p || !(*p) ) {

+        return 0;

+    }

+    if ( !XMLUtil::IsNameStartChar( *p ) ) {

+        return 0;

+    }

+

+    char* const start = p;

+    ++p;

+    while ( *p && XMLUtil::IsNameChar( *p ) ) {

+        ++p;

+    }

+

+    Set( start, p, 0 );

+    return p;

+}

+

+

+void StrPair::CollapseWhitespace()

+{

+    // Adjusting _start would cause undefined behavior on delete[]

+    TIXMLASSERT( ( _flags & NEEDS_DELETE ) == 0 );

+    // Trim leading space.

+    _start = XMLUtil::SkipWhiteSpace( _start, 0 );

+

+    if ( *_start ) {

+        const char* p = _start;	// the read pointer

+        char* q = _start;	// the write pointer

+

+        while( *p ) {

+            if ( XMLUtil::IsWhiteSpace( *p )) {

+                p = XMLUtil::SkipWhiteSpace( p, 0 );

+                if ( *p == 0 ) {

+                    break;    // don't write to q; this trims the trailing space.

+                }

+                *q = ' ';

+                ++q;

+            }

+            *q = *p;

+            ++q;

+            ++p;

+        }

+        *q = 0;

+    }

+}

+

+

+const char* StrPair::GetStr()

+{

+    TIXMLASSERT( _start );

+    TIXMLASSERT( _end );

+    if ( _flags & NEEDS_FLUSH ) {

+        *_end = 0;

+        _flags ^= NEEDS_FLUSH;

+

+        if ( _flags ) {

+            const char* p = _start;	// the read pointer

+            char* q = _start;	// the write pointer

+

+            while( p < _end ) {

+                if ( (_flags & NEEDS_NEWLINE_NORMALIZATION) && *p == CR ) {

+                    // CR-LF pair becomes LF

+                    // CR alone becomes LF

+                    // LF-CR becomes LF

+                    if ( *(p+1) == LF ) {

+                        p += 2;

+                    }

+                    else {

+                        ++p;

+                    }

+                    *q = LF;

+                    ++q;

+                }

+                else if ( (_flags & NEEDS_NEWLINE_NORMALIZATION) && *p == LF ) {

+                    if ( *(p+1) == CR ) {

+                        p += 2;

+                    }

+                    else {

+                        ++p;

+                    }

+                    *q = LF;

+                    ++q;

+                }

+                else if ( (_flags & NEEDS_ENTITY_PROCESSING) && *p == '&' ) {

+                    // Entities handled by tinyXML2:

+                    // - special entities in the entity table [in/out]

+                    // - numeric character reference [in]

+                    //   &#20013; or &#x4e2d;

+

+                    if ( *(p+1) == '#' ) {

+                        const int buflen = 10;

+                        char buf[buflen] = { 0 };

+                        int len = 0;

+                        char* adjusted = const_cast<char*>( XMLUtil::GetCharacterRef( p, buf, &len ) );

+                        if ( adjusted == 0 ) {

+                            *q = *p;

+                            ++p;

+                            ++q;

+                        }

+                        else {

+                            TIXMLASSERT( 0 <= len && len <= buflen );

+                            TIXMLASSERT( q + len <= adjusted );

+                            p = adjusted;

+                            memcpy( q, buf, len );

+                            q += len;

+                        }

+                    }

+                    else {

+                        bool entityFound = false;

+                        for( int i = 0; i < NUM_ENTITIES; ++i ) {

+                            const Entity& entity = entities[i];

+                            if ( strncmp( p + 1, entity.pattern, entity.length ) == 0

+                                    && *( p + entity.length + 1 ) == ';' ) {

+                                // Found an entity - convert.

+                                *q = entity.value;

+                                ++q;

+                                p += entity.length + 2;

+                                entityFound = true;

+                                break;

+                            }

+                        }

+                        if ( !entityFound ) {

+                            // fixme: treat as error?

+                            ++p;

+                            ++q;

+                        }

+                    }

+                }

+                else {

+                    *q = *p;

+                    ++p;

+                    ++q;

+                }

+            }

+            *q = 0;

+        }

+        // The loop below has plenty going on, and this

+        // is a less useful mode. Break it out.

+        if ( _flags & NEEDS_WHITESPACE_COLLAPSING ) {

+            CollapseWhitespace();

+        }

+        _flags = (_flags & NEEDS_DELETE);

+    }

+    TIXMLASSERT( _start );

+    return _start;

+}

+

+

+

+

+// --------- XMLUtil ----------- //

+

+const char* XMLUtil::writeBoolTrue  = "true";

+const char* XMLUtil::writeBoolFalse = "false";

+

+void XMLUtil::SetBoolSerialization(const char* writeTrue, const char* writeFalse)

+{

+	static const char* defTrue  = "true";

+	static const char* defFalse = "false";

+

+	writeBoolTrue = (writeTrue) ? writeTrue : defTrue;

+	writeBoolFalse = (writeFalse) ? writeFalse : defFalse;

+}

+

+

+const char* XMLUtil::ReadBOM( const char* p, bool* bom )

+{

+    TIXMLASSERT( p );

+    TIXMLASSERT( bom );

+    *bom = false;

+    const unsigned char* pu = reinterpret_cast<const unsigned char*>(p);

+    // Check for BOM:

+    if (    *(pu+0) == TIXML_UTF_LEAD_0

+            && *(pu+1) == TIXML_UTF_LEAD_1

+            && *(pu+2) == TIXML_UTF_LEAD_2 ) {

+        *bom = true;

+        p += 3;

+    }

+    TIXMLASSERT( p );

+    return p;

+}

+

+

+void XMLUtil::ConvertUTF32ToUTF8( unsigned long input, char* output, int* length )

+{

+    const unsigned long BYTE_MASK = 0xBF;

+    const unsigned long BYTE_MARK = 0x80;

+    const unsigned long FIRST_BYTE_MARK[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };

+

+    if (input < 0x80) {

+        *length = 1;

+    }

+    else if ( input < 0x800 ) {

+        *length = 2;

+    }

+    else if ( input < 0x10000 ) {

+        *length = 3;

+    }

+    else if ( input < 0x200000 ) {

+        *length = 4;

+    }

+    else {

+        *length = 0;    // This code won't convert this correctly anyway.

+        return;

+    }

+

+    output += *length;

+

+    // Scary scary fall throughs are annotated with carefully designed comments

+    // to suppress compiler warnings such as -Wimplicit-fallthrough in gcc

+    switch (*length) {

+        case 4:

+            --output;

+            *output = (char)((input | BYTE_MARK) & BYTE_MASK);

+            input >>= 6;

+            //fall through

+        case 3:

+            --output;

+            *output = (char)((input | BYTE_MARK) & BYTE_MASK);

+            input >>= 6;

+            //fall through

+        case 2:

+            --output;

+            *output = (char)((input | BYTE_MARK) & BYTE_MASK);

+            input >>= 6;

+            //fall through

+        case 1:

+            --output;

+            *output = (char)(input | FIRST_BYTE_MARK[*length]);

+            break;

+        default:

+            TIXMLASSERT( false );

+    }

+}

+

+

+const char* XMLUtil::GetCharacterRef( const char* p, char* value, int* length )

+{

+    // Presume an entity, and pull it out.

+    *length = 0;

+

+    if ( *(p+1) == '#' && *(p+2) ) {

+        unsigned long ucs = 0;

+        TIXMLASSERT( sizeof( ucs ) >= 4 );

+        ptrdiff_t delta = 0;

+        unsigned mult = 1;

+        static const char SEMICOLON = ';';

+

+        if ( *(p+2) == 'x' ) {

+            // Hexadecimal.

+            const char* q = p+3;

+            if ( !(*q) ) {

+                return 0;

+            }

+

+            q = strchr( q, SEMICOLON );

+

+            if ( !q ) {

+                return 0;

+            }

+            TIXMLASSERT( *q == SEMICOLON );

+

+            delta = q-p;

+            --q;

+

+            while ( *q != 'x' ) {

+                unsigned int digit = 0;

+

+                if ( *q >= '0' && *q <= '9' ) {

+                    digit = *q - '0';

+                }

+                else if ( *q >= 'a' && *q <= 'f' ) {

+                    digit = *q - 'a' + 10;

+                }

+                else if ( *q >= 'A' && *q <= 'F' ) {

+                    digit = *q - 'A' + 10;

+                }

+                else {

+                    return 0;

+                }

+                TIXMLASSERT( digit < 16 );

+                TIXMLASSERT( digit == 0 || mult <= UINT_MAX / digit );

+                const unsigned int digitScaled = mult * digit;

+                TIXMLASSERT( ucs <= ULONG_MAX - digitScaled );

+                ucs += digitScaled;

+                TIXMLASSERT( mult <= UINT_MAX / 16 );

+                mult *= 16;

+                --q;

+            }

+        }

+        else {

+            // Decimal.

+            const char* q = p+2;

+            if ( !(*q) ) {

+                return 0;

+            }

+

+            q = strchr( q, SEMICOLON );

+

+            if ( !q ) {

+                return 0;

+            }

+            TIXMLASSERT( *q == SEMICOLON );

+

+            delta = q-p;

+            --q;

+

+            while ( *q != '#' ) {

+                if ( *q >= '0' && *q <= '9' ) {

+                    const unsigned int digit = *q - '0';

+                    TIXMLASSERT( digit < 10 );

+                    TIXMLASSERT( digit == 0 || mult <= UINT_MAX / digit );

+                    const unsigned int digitScaled = mult * digit;

+                    TIXMLASSERT( ucs <= ULONG_MAX - digitScaled );

+                    ucs += digitScaled;

+                }

+                else {

+                    return 0;

+                }

+                TIXMLASSERT( mult <= UINT_MAX / 10 );

+                mult *= 10;

+                --q;

+            }

+        }

+        // convert the UCS to UTF-8

+        ConvertUTF32ToUTF8( ucs, value, length );

+        return p + delta + 1;

+    }

+    return p+1;

+}

+

+

+void XMLUtil::ToStr( int v, char* buffer, int bufferSize )

+{

+    TIXML_SNPRINTF( buffer, bufferSize, "%d", v );

+}

+

+

+void XMLUtil::ToStr( unsigned v, char* buffer, int bufferSize )

+{

+    TIXML_SNPRINTF( buffer, bufferSize, "%u", v );

+}

+

+

+void XMLUtil::ToStr( bool v, char* buffer, int bufferSize )

+{

+    TIXML_SNPRINTF( buffer, bufferSize, "%s", v ? writeBoolTrue : writeBoolFalse);

+}

+

+/*

+	ToStr() of a number is a very tricky topic.

+	https://github.com/leethomason/tinyxml2/issues/106

+*/

+void XMLUtil::ToStr( float v, char* buffer, int bufferSize )

+{

+    TIXML_SNPRINTF( buffer, bufferSize, "%.8g", v );

+}

+

+

+void XMLUtil::ToStr( double v, char* buffer, int bufferSize )

+{

+    TIXML_SNPRINTF( buffer, bufferSize, "%.17g", v );

+}

+

+

+void XMLUtil::ToStr(int64_t v, char* buffer, int bufferSize)

+{

+	// horrible syntax trick to make the compiler happy about %lld

+	TIXML_SNPRINTF(buffer, bufferSize, "%lld", (long long)v);

+}

+

+

+bool XMLUtil::ToInt( const char* str, int* value )

+{

+    if ( TIXML_SSCANF( str, "%d", value ) == 1 ) {

+        return true;

+    }

+    return false;

+}

+

+bool XMLUtil::ToUnsigned( const char* str, unsigned *value )

+{

+    if ( TIXML_SSCANF( str, "%u", value ) == 1 ) {

+        return true;

+    }

+    return false;

+}

+

+bool XMLUtil::ToBool( const char* str, bool* value )

+{

+    int ival = 0;

+    if ( ToInt( str, &ival )) {

+        *value = (ival==0) ? false : true;

+        return true;

+    }

+    if ( StringEqual( str, "true" ) ) {

+        *value = true;

+        return true;

+    }

+    else if ( StringEqual( str, "false" ) ) {

+        *value = false;

+        return true;

+    }

+    return false;

+}

+

+

+bool XMLUtil::ToFloat( const char* str, float* value )

+{

+    if ( TIXML_SSCANF( str, "%f", value ) == 1 ) {

+        return true;

+    }

+    return false;

+}

+

+

+bool XMLUtil::ToDouble( const char* str, double* value )

+{

+    if ( TIXML_SSCANF( str, "%lf", value ) == 1 ) {

+        return true;

+    }

+    return false;

+}

+

+

+bool XMLUtil::ToInt64(const char* str, int64_t* value)

+{

+	long long v = 0;	// horrible syntax trick to make the compiler happy about %lld

+	if (TIXML_SSCANF(str, "%lld", &v) == 1) {

+		*value = (int64_t)v;

+		return true;

+	}

+	return false;

+}

+

+

+char* XMLDocument::Identify( char* p, XMLNode** node )

+{

+    TIXMLASSERT( node );

+    TIXMLASSERT( p );

+    char* const start = p;

+    int const startLine = _parseCurLineNum;

+    p = XMLUtil::SkipWhiteSpace( p, &_parseCurLineNum );

+    if( !*p ) {

+        *node = 0;

+        TIXMLASSERT( p );

+        return p;

+    }

+

+    // These strings define the matching patterns:

+    static const char* xmlHeader		= { "<?" };

+    static const char* commentHeader	= { "<!--" };

+    static const char* cdataHeader		= { "<![CDATA[" };

+    static const char* dtdHeader		= { "<!" };

+    static const char* elementHeader	= { "<" };	// and a header for everything else; check last.

+

+    static const int xmlHeaderLen		= 2;

+    static const int commentHeaderLen	= 4;

+    static const int cdataHeaderLen		= 9;

+    static const int dtdHeaderLen		= 2;

+    static const int elementHeaderLen	= 1;

+

+    TIXMLASSERT( sizeof( XMLComment ) == sizeof( XMLUnknown ) );		// use same memory pool

+    TIXMLASSERT( sizeof( XMLComment ) == sizeof( XMLDeclaration ) );	// use same memory pool

+    XMLNode* returnNode = 0;

+    if ( XMLUtil::StringEqual( p, xmlHeader, xmlHeaderLen ) ) {

+        returnNode = CreateUnlinkedNode<XMLDeclaration>( _commentPool );

+        returnNode->_parseLineNum = _parseCurLineNum;

+        p += xmlHeaderLen;

+    }

+    else if ( XMLUtil::StringEqual( p, commentHeader, commentHeaderLen ) ) {

+        returnNode = CreateUnlinkedNode<XMLComment>( _commentPool );

+        returnNode->_parseLineNum = _parseCurLineNum;

+        p += commentHeaderLen;

+    }

+    else if ( XMLUtil::StringEqual( p, cdataHeader, cdataHeaderLen ) ) {

+        XMLText* text = CreateUnlinkedNode<XMLText>( _textPool );

+        returnNode = text;

+        returnNode->_parseLineNum = _parseCurLineNum;

+        p += cdataHeaderLen;

+        text->SetCData( true );

+    }

+    else if ( XMLUtil::StringEqual( p, dtdHeader, dtdHeaderLen ) ) {

+        returnNode = CreateUnlinkedNode<XMLUnknown>( _commentPool );

+        returnNode->_parseLineNum = _parseCurLineNum;

+        p += dtdHeaderLen;

+    }

+    else if ( XMLUtil::StringEqual( p, elementHeader, elementHeaderLen ) ) {

+        returnNode =  CreateUnlinkedNode<XMLElement>( _elementPool );

+        returnNode->_parseLineNum = _parseCurLineNum;

+        p += elementHeaderLen;

+    }

+    else {

+        returnNode = CreateUnlinkedNode<XMLText>( _textPool );

+        returnNode->_parseLineNum = _parseCurLineNum; // Report line of first non-whitespace character

+        p = start;	// Back it up, all the text counts.

+        _parseCurLineNum = startLine;

+    }

+

+    TIXMLASSERT( returnNode );

+    TIXMLASSERT( p );

+    *node = returnNode;

+    return p;

+}

+

+

+bool XMLDocument::Accept( XMLVisitor* visitor ) const

+{

+    TIXMLASSERT( visitor );

+    if ( visitor->VisitEnter( *this ) ) {

+        for ( const XMLNode* node=FirstChild(); node; node=node->NextSibling() ) {

+            if ( !node->Accept( visitor ) ) {

+                break;

+            }

+        }

+    }

+    return visitor->VisitExit( *this );

+}

+

+

+// --------- XMLNode ----------- //

+

+XMLNode::XMLNode( XMLDocument* doc ) :

+    _document( doc ),

+    _parent( 0 ),

+    _value(),

+    _parseLineNum( 0 ),

+    _firstChild( 0 ), _lastChild( 0 ),

+    _prev( 0 ), _next( 0 ),

+	_userData( 0 ),

+    _memPool( 0 )

+{

+}

+

+

+XMLNode::~XMLNode()

+{

+    DeleteChildren();

+    if ( _parent ) {

+        _parent->Unlink( this );

+    }

+}

+

+const char* XMLNode::Value() const 

+{

+    // Edge case: XMLDocuments don't have a Value. Return null.

+    if ( this->ToDocument() )

+        return 0;

+    return _value.GetStr();

+}

+

+void XMLNode::SetValue( const char* str, bool staticMem )

+{

+    if ( staticMem ) {

+        _value.SetInternedStr( str );

+    }

+    else {

+        _value.SetStr( str );

+    }

+}

+

+XMLNode* XMLNode::DeepClone(XMLDocument* target) const

+{

+	XMLNode* clone = this->ShallowClone(target);

+	if (!clone) return 0;

+

+	for (const XMLNode* child = this->FirstChild(); child; child = child->NextSibling()) {

+		XMLNode* childClone = child->DeepClone(target);

+		TIXMLASSERT(childClone);

+		clone->InsertEndChild(childClone);

+	}

+	return clone;

+}

+

+void XMLNode::DeleteChildren()

+{

+    while( _firstChild ) {

+        TIXMLASSERT( _lastChild );

+        DeleteChild( _firstChild );

+    }

+    _firstChild = _lastChild = 0;

+}

+

+

+void XMLNode::Unlink( XMLNode* child )

+{

+    TIXMLASSERT( child );

+    TIXMLASSERT( child->_document == _document );

+    TIXMLASSERT( child->_parent == this );

+    if ( child == _firstChild ) {

+        _firstChild = _firstChild->_next;

+    }

+    if ( child == _lastChild ) {

+        _lastChild = _lastChild->_prev;

+    }

+

+    if ( child->_prev ) {

+        child->_prev->_next = child->_next;

+    }

+    if ( child->_next ) {

+        child->_next->_prev = child->_prev;

+    }

+	child->_next = 0;

+	child->_prev = 0;

+	child->_parent = 0;

+}

+

+

+void XMLNode::DeleteChild( XMLNode* node )

+{

+    TIXMLASSERT( node );

+    TIXMLASSERT( node->_document == _document );

+    TIXMLASSERT( node->_parent == this );

+    Unlink( node );

+	TIXMLASSERT(node->_prev == 0);

+	TIXMLASSERT(node->_next == 0);

+	TIXMLASSERT(node->_parent == 0);

+    DeleteNode( node );

+}

+

+

+XMLNode* XMLNode::InsertEndChild( XMLNode* addThis )

+{

+    TIXMLASSERT( addThis );

+    if ( addThis->_document != _document ) {

+        TIXMLASSERT( false );

+        return 0;

+    }

+    InsertChildPreamble( addThis );

+

+    if ( _lastChild ) {

+        TIXMLASSERT( _firstChild );

+        TIXMLASSERT( _lastChild->_next == 0 );

+        _lastChild->_next = addThis;

+        addThis->_prev = _lastChild;

+        _lastChild = addThis;

+

+        addThis->_next = 0;

+    }

+    else {

+        TIXMLASSERT( _firstChild == 0 );

+        _firstChild = _lastChild = addThis;

+

+        addThis->_prev = 0;

+        addThis->_next = 0;

+    }

+    addThis->_parent = this;

+    return addThis;

+}

+

+

+XMLNode* XMLNode::InsertFirstChild( XMLNode* addThis )

+{

+    TIXMLASSERT( addThis );

+    if ( addThis->_document != _document ) {

+        TIXMLASSERT( false );

+        return 0;

+    }

+    InsertChildPreamble( addThis );

+

+    if ( _firstChild ) {

+        TIXMLASSERT( _lastChild );

+        TIXMLASSERT( _firstChild->_prev == 0 );

+

+        _firstChild->_prev = addThis;

+        addThis->_next = _firstChild;

+        _firstChild = addThis;

+

+        addThis->_prev = 0;

+    }

+    else {

+        TIXMLASSERT( _lastChild == 0 );

+        _firstChild = _lastChild = addThis;

+

+        addThis->_prev = 0;

+        addThis->_next = 0;

+    }

+    addThis->_parent = this;

+    return addThis;

+}

+

+

+XMLNode* XMLNode::InsertAfterChild( XMLNode* afterThis, XMLNode* addThis )

+{

+    TIXMLASSERT( addThis );

+    if ( addThis->_document != _document ) {

+        TIXMLASSERT( false );

+        return 0;

+    }

+

+    TIXMLASSERT( afterThis );

+

+    if ( afterThis->_parent != this ) {

+        TIXMLASSERT( false );

+        return 0;

+    }

+    if ( afterThis == addThis ) {

+        // Current state: BeforeThis -> AddThis -> OneAfterAddThis

+        // Now AddThis must disappear from it's location and then

+        // reappear between BeforeThis and OneAfterAddThis.

+        // So just leave it where it is.

+        return addThis;

+    }

+

+    if ( afterThis->_next == 0 ) {

+        // The last node or the only node.

+        return InsertEndChild( addThis );

+    }

+    InsertChildPreamble( addThis );

+    addThis->_prev = afterThis;

+    addThis->_next = afterThis->_next;

+    afterThis->_next->_prev = addThis;

+    afterThis->_next = addThis;

+    addThis->_parent = this;

+    return addThis;

+}

+

+

+

+

+const XMLElement* XMLNode::FirstChildElement( const char* name ) const

+{

+    for( const XMLNode* node = _firstChild; node; node = node->_next ) {

+        const XMLElement* element = node->ToElementWithName( name );

+        if ( element ) {

+            return element;

+        }

+    }

+    return 0;

+}

+

+

+const XMLElement* XMLNode::LastChildElement( const char* name ) const

+{

+    for( const XMLNode* node = _lastChild; node; node = node->_prev ) {

+        const XMLElement* element = node->ToElementWithName( name );

+        if ( element ) {

+            return element;

+        }

+    }

+    return 0;

+}

+

+

+const XMLElement* XMLNode::NextSiblingElement( const char* name ) const

+{

+    for( const XMLNode* node = _next; node; node = node->_next ) {

+        const XMLElement* element = node->ToElementWithName( name );

+        if ( element ) {

+            return element;

+        }

+    }

+    return 0;

+}

+

+

+const XMLElement* XMLNode::PreviousSiblingElement( const char* name ) const

+{

+    for( const XMLNode* node = _prev; node; node = node->_prev ) {

+        const XMLElement* element = node->ToElementWithName( name );

+        if ( element ) {

+            return element;

+        }

+    }

+    return 0;

+}

+

+

+char* XMLNode::ParseDeep( char* p, StrPair* parentEndTag, int* curLineNumPtr )

+{

+    // This is a recursive method, but thinking about it "at the current level"

+    // it is a pretty simple flat list:

+    //		<foo/>

+    //		<!-- comment -->

+    //

+    // With a special case:

+    //		<foo>

+    //		</foo>

+    //		<!-- comment -->

+    //

+    // Where the closing element (/foo) *must* be the next thing after the opening

+    // element, and the names must match. BUT the tricky bit is that the closing

+    // element will be read by the child.

+    //

+    // 'endTag' is the end tag for this node, it is returned by a call to a child.

+    // 'parentEnd' is the end tag for the parent, which is filled in and returned.

+

+    while( p && *p ) {

+        XMLNode* node = 0;

+

+        p = _document->Identify( p, &node );

+        TIXMLASSERT( p );

+        if ( node == 0 ) {

+            break;

+        }

+

+        int initialLineNum = node->_parseLineNum;

+

+        StrPair endTag;

+        p = node->ParseDeep( p, &endTag, curLineNumPtr );

+        if ( !p ) {

+            DeleteNode( node );

+            if ( !_document->Error() ) {

+                _document->SetError( XML_ERROR_PARSING, initialLineNum, 0);

+            }

+            break;

+        }

+

+        XMLDeclaration* decl = node->ToDeclaration();

+        if ( decl ) {

+            // Declarations are only allowed at document level

+            bool wellLocated = ( ToDocument() != 0 );

+            if ( wellLocated ) {

+                // Multiple declarations are allowed but all declarations

+                // must occur before anything else

+                for ( const XMLNode* existingNode = _document->FirstChild(); existingNode; existingNode = existingNode->NextSibling() ) {

+                    if ( !existingNode->ToDeclaration() ) {

+                        wellLocated = false;

+                        break;

+                    }

+                }

+            }

+            if ( !wellLocated ) {

+                _document->SetError( XML_ERROR_PARSING_DECLARATION, initialLineNum, "XMLDeclaration value=%s", decl->Value());

+                DeleteNode( node );

+                break;

+            }

+        }

+

+        XMLElement* ele = node->ToElement();

+        if ( ele ) {

+            // We read the end tag. Return it to the parent.

+            if ( ele->ClosingType() == XMLElement::CLOSING ) {

+                if ( parentEndTag ) {

+                    ele->_value.TransferTo( parentEndTag );

+                }

+                node->_memPool->SetTracked();   // created and then immediately deleted.

+                DeleteNode( node );

+                return p;

+            }

+

+            // Handle an end tag returned to this level.

+            // And handle a bunch of annoying errors.

+            bool mismatch = false;

+            if ( endTag.Empty() ) {

+                if ( ele->ClosingType() == XMLElement::OPEN ) {

+                    mismatch = true;

+                }

+            }

+            else {

+                if ( ele->ClosingType() != XMLElement::OPEN ) {

+                    mismatch = true;

+                }

+                else if ( !XMLUtil::StringEqual( endTag.GetStr(), ele->Name() ) ) {

+                    mismatch = true;

+                }

+            }

+            if ( mismatch ) {

+                _document->SetError( XML_ERROR_MISMATCHED_ELEMENT, initialLineNum, "XMLElement name=%s", ele->Name());

+                DeleteNode( node );

+                break;

+            }

+        }

+        InsertEndChild( node );

+    }

+    return 0;

+}

+

+/*static*/ void XMLNode::DeleteNode( XMLNode* node )

+{

+    if ( node == 0 ) {

+        return;

+    }

+	TIXMLASSERT(node->_document);

+	if (!node->ToDocument()) {

+		node->_document->MarkInUse(node);

+	}

+

+    MemPool* pool = node->_memPool;

+    node->~XMLNode();

+    pool->Free( node );

+}

+

+void XMLNode::InsertChildPreamble( XMLNode* insertThis ) const

+{

+    TIXMLASSERT( insertThis );

+    TIXMLASSERT( insertThis->_document == _document );

+

+	if (insertThis->_parent) {

+        insertThis->_parent->Unlink( insertThis );

+	}

+	else {

+		insertThis->_document->MarkInUse(insertThis);

+        insertThis->_memPool->SetTracked();

+	}

+}

+

+const XMLElement* XMLNode::ToElementWithName( const char* name ) const

+{

+    const XMLElement* element = this->ToElement();

+    if ( element == 0 ) {

+        return 0;

+    }

+    if ( name == 0 ) {

+        return element;

+    }

+    if ( XMLUtil::StringEqual( element->Name(), name ) ) {

+       return element;

+    }

+    return 0;

+}

+

+// --------- XMLText ---------- //

+char* XMLText::ParseDeep( char* p, StrPair*, int* curLineNumPtr )

+{

+    if ( this->CData() ) {

+        p = _value.ParseText( p, "]]>", StrPair::NEEDS_NEWLINE_NORMALIZATION, curLineNumPtr );

+        if ( !p ) {

+            _document->SetError( XML_ERROR_PARSING_CDATA, _parseLineNum, 0 );

+        }

+        return p;

+    }

+    else {

+        int flags = _document->ProcessEntities() ? StrPair::TEXT_ELEMENT : StrPair::TEXT_ELEMENT_LEAVE_ENTITIES;

+        if ( _document->WhitespaceMode() == COLLAPSE_WHITESPACE ) {

+            flags |= StrPair::NEEDS_WHITESPACE_COLLAPSING;

+        }

+

+        p = _value.ParseText( p, "<", flags, curLineNumPtr );

+        if ( p && *p ) {

+            return p-1;

+        }

+        if ( !p ) {

+            _document->SetError( XML_ERROR_PARSING_TEXT, _parseLineNum, 0 );

+        }

+    }

+    return 0;

+}

+

+

+XMLNode* XMLText::ShallowClone( XMLDocument* doc ) const

+{

+    if ( !doc ) {

+        doc = _document;

+    }

+    XMLText* text = doc->NewText( Value() );	// fixme: this will always allocate memory. Intern?

+    text->SetCData( this->CData() );

+    return text;

+}

+

+

+bool XMLText::ShallowEqual( const XMLNode* compare ) const

+{

+    TIXMLASSERT( compare );

+    const XMLText* text = compare->ToText();

+    return ( text && XMLUtil::StringEqual( text->Value(), Value() ) );

+}

+

+

+bool XMLText::Accept( XMLVisitor* visitor ) const

+{

+    TIXMLASSERT( visitor );

+    return visitor->Visit( *this );

+}

+

+

+// --------- XMLComment ---------- //

+

+XMLComment::XMLComment( XMLDocument* doc ) : XMLNode( doc )

+{

+}

+

+

+XMLComment::~XMLComment()

+{

+}

+

+

+char* XMLComment::ParseDeep( char* p, StrPair*, int* curLineNumPtr )

+{

+    // Comment parses as text.

+    p = _value.ParseText( p, "-->", StrPair::COMMENT, curLineNumPtr );

+    if ( p == 0 ) {

+        _document->SetError( XML_ERROR_PARSING_COMMENT, _parseLineNum, 0 );

+    }

+    return p;

+}

+

+

+XMLNode* XMLComment::ShallowClone( XMLDocument* doc ) const

+{

+    if ( !doc ) {

+        doc = _document;

+    }

+    XMLComment* comment = doc->NewComment( Value() );	// fixme: this will always allocate memory. Intern?

+    return comment;

+}

+

+

+bool XMLComment::ShallowEqual( const XMLNode* compare ) const

+{

+    TIXMLASSERT( compare );

+    const XMLComment* comment = compare->ToComment();

+    return ( comment && XMLUtil::StringEqual( comment->Value(), Value() ));

+}

+

+

+bool XMLComment::Accept( XMLVisitor* visitor ) const

+{

+    TIXMLASSERT( visitor );

+    return visitor->Visit( *this );

+}

+

+

+// --------- XMLDeclaration ---------- //

+

+XMLDeclaration::XMLDeclaration( XMLDocument* doc ) : XMLNode( doc )

+{

+}

+

+

+XMLDeclaration::~XMLDeclaration()

+{

+    //printf( "~XMLDeclaration\n" );

+}

+

+

+char* XMLDeclaration::ParseDeep( char* p, StrPair*, int* curLineNumPtr )

+{

+    // Declaration parses as text.

+    p = _value.ParseText( p, "?>", StrPair::NEEDS_NEWLINE_NORMALIZATION, curLineNumPtr );

+    if ( p == 0 ) {

+        _document->SetError( XML_ERROR_PARSING_DECLARATION, _parseLineNum, 0 );

+    }

+    return p;

+}

+

+

+XMLNode* XMLDeclaration::ShallowClone( XMLDocument* doc ) const

+{

+    if ( !doc ) {

+        doc = _document;

+    }

+    XMLDeclaration* dec = doc->NewDeclaration( Value() );	// fixme: this will always allocate memory. Intern?

+    return dec;

+}

+

+

+bool XMLDeclaration::ShallowEqual( const XMLNode* compare ) const

+{

+    TIXMLASSERT( compare );

+    const XMLDeclaration* declaration = compare->ToDeclaration();

+    return ( declaration && XMLUtil::StringEqual( declaration->Value(), Value() ));

+}

+

+

+

+bool XMLDeclaration::Accept( XMLVisitor* visitor ) const

+{

+    TIXMLASSERT( visitor );

+    return visitor->Visit( *this );

+}

+

+// --------- XMLUnknown ---------- //

+

+XMLUnknown::XMLUnknown( XMLDocument* doc ) : XMLNode( doc )

+{

+}

+

+

+XMLUnknown::~XMLUnknown()

+{

+}

+

+

+char* XMLUnknown::ParseDeep( char* p, StrPair*, int* curLineNumPtr )

+{

+    // Unknown parses as text.

+    p = _value.ParseText( p, ">", StrPair::NEEDS_NEWLINE_NORMALIZATION, curLineNumPtr );

+    if ( !p ) {

+        _document->SetError( XML_ERROR_PARSING_UNKNOWN, _parseLineNum, 0 );

+    }

+    return p;

+}

+

+

+XMLNode* XMLUnknown::ShallowClone( XMLDocument* doc ) const

+{

+    if ( !doc ) {

+        doc = _document;

+    }

+    XMLUnknown* text = doc->NewUnknown( Value() );	// fixme: this will always allocate memory. Intern?

+    return text;

+}

+

+

+bool XMLUnknown::ShallowEqual( const XMLNode* compare ) const

+{

+    TIXMLASSERT( compare );

+    const XMLUnknown* unknown = compare->ToUnknown();

+    return ( unknown && XMLUtil::StringEqual( unknown->Value(), Value() ));

+}

+

+

+bool XMLUnknown::Accept( XMLVisitor* visitor ) const

+{

+    TIXMLASSERT( visitor );

+    return visitor->Visit( *this );

+}

+

+// --------- XMLAttribute ---------- //

+

+const char* XMLAttribute::Name() const 

+{

+    return _name.GetStr();

+}

+

+const char* XMLAttribute::Value() const 

+{

+    return _value.GetStr();

+}

+

+char* XMLAttribute::ParseDeep( char* p, bool processEntities, int* curLineNumPtr )

+{

+    // Parse using the name rules: bug fix, was using ParseText before

+    p = _name.ParseName( p );

+    if ( !p || !*p ) {

+        return 0;

+    }

+

+    // Skip white space before =

+    p = XMLUtil::SkipWhiteSpace( p, curLineNumPtr );

+    if ( *p != '=' ) {

+        return 0;

+    }

+

+    ++p;	// move up to opening quote

+    p = XMLUtil::SkipWhiteSpace( p, curLineNumPtr );

+    if ( *p != '\"' && *p != '\'' ) {

+        return 0;

+    }

+

+    char endTag[2] = { *p, 0 };

+    ++p;	// move past opening quote

+

+    p = _value.ParseText( p, endTag, processEntities ? StrPair::ATTRIBUTE_VALUE : StrPair::ATTRIBUTE_VALUE_LEAVE_ENTITIES, curLineNumPtr );

+    return p;

+}

+

+

+void XMLAttribute::SetName( const char* n )

+{

+    _name.SetStr( n );

+}

+

+

+XMLError XMLAttribute::QueryIntValue( int* value ) const

+{

+    if ( XMLUtil::ToInt( Value(), value )) {

+        return XML_SUCCESS;

+    }

+    return XML_WRONG_ATTRIBUTE_TYPE;

+}

+

+

+XMLError XMLAttribute::QueryUnsignedValue( unsigned int* value ) const

+{

+    if ( XMLUtil::ToUnsigned( Value(), value )) {

+        return XML_SUCCESS;

+    }

+    return XML_WRONG_ATTRIBUTE_TYPE;

+}

+

+

+XMLError XMLAttribute::QueryInt64Value(int64_t* value) const

+{

+	if (XMLUtil::ToInt64(Value(), value)) {

+		return XML_SUCCESS;

+	}

+	return XML_WRONG_ATTRIBUTE_TYPE;

+}

+

+

+XMLError XMLAttribute::QueryBoolValue( bool* value ) const

+{

+    if ( XMLUtil::ToBool( Value(), value )) {

+        return XML_SUCCESS;

+    }

+    return XML_WRONG_ATTRIBUTE_TYPE;

+}

+

+

+XMLError XMLAttribute::QueryFloatValue( float* value ) const

+{

+    if ( XMLUtil::ToFloat( Value(), value )) {

+        return XML_SUCCESS;

+    }

+    return XML_WRONG_ATTRIBUTE_TYPE;

+}

+

+

+XMLError XMLAttribute::QueryDoubleValue( double* value ) const

+{

+    if ( XMLUtil::ToDouble( Value(), value )) {

+        return XML_SUCCESS;

+    }

+    return XML_WRONG_ATTRIBUTE_TYPE;

+}

+

+

+void XMLAttribute::SetAttribute( const char* v )

+{

+    _value.SetStr( v );

+}

+

+

+void XMLAttribute::SetAttribute( int v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    _value.SetStr( buf );

+}

+

+

+void XMLAttribute::SetAttribute( unsigned v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    _value.SetStr( buf );

+}

+

+

+void XMLAttribute::SetAttribute(int64_t v)

+{

+	char buf[BUF_SIZE];

+	XMLUtil::ToStr(v, buf, BUF_SIZE);

+	_value.SetStr(buf);

+}

+

+

+

+void XMLAttribute::SetAttribute( bool v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    _value.SetStr( buf );

+}

+

+void XMLAttribute::SetAttribute( double v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    _value.SetStr( buf );

+}

+

+void XMLAttribute::SetAttribute( float v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    _value.SetStr( buf );

+}

+

+

+// --------- XMLElement ---------- //

+XMLElement::XMLElement( XMLDocument* doc ) : XMLNode( doc ),

+    _closingType( OPEN ),

+    _rootAttribute( 0 )

+{

+}

+

+

+XMLElement::~XMLElement()

+{

+    while( _rootAttribute ) {

+        XMLAttribute* next = _rootAttribute->_next;

+        DeleteAttribute( _rootAttribute );

+        _rootAttribute = next;

+    }

+}

+

+

+const XMLAttribute* XMLElement::FindAttribute( const char* name ) const

+{

+    for( XMLAttribute* a = _rootAttribute; a; a = a->_next ) {

+        if ( XMLUtil::StringEqual( a->Name(), name ) ) {

+            return a;

+        }

+    }

+    return 0;

+}

+

+

+const char* XMLElement::Attribute( const char* name, const char* value ) const

+{

+    const XMLAttribute* a = FindAttribute( name );

+    if ( !a ) {

+        return 0;

+    }

+    if ( !value || XMLUtil::StringEqual( a->Value(), value )) {

+        return a->Value();

+    }

+    return 0;

+}

+

+int XMLElement::IntAttribute(const char* name, int defaultValue) const 

+{

+	int i = defaultValue;

+	QueryIntAttribute(name, &i);

+	return i;

+}

+

+unsigned XMLElement::UnsignedAttribute(const char* name, unsigned defaultValue) const 

+{

+	unsigned i = defaultValue;

+	QueryUnsignedAttribute(name, &i);

+	return i;

+}

+

+int64_t XMLElement::Int64Attribute(const char* name, int64_t defaultValue) const 

+{

+	int64_t i = defaultValue;

+	QueryInt64Attribute(name, &i);

+	return i;

+}

+

+bool XMLElement::BoolAttribute(const char* name, bool defaultValue) const 

+{

+	bool b = defaultValue;

+	QueryBoolAttribute(name, &b);

+	return b;

+}

+

+double XMLElement::DoubleAttribute(const char* name, double defaultValue) const 

+{

+	double d = defaultValue;

+	QueryDoubleAttribute(name, &d);

+	return d;

+}

+

+float XMLElement::FloatAttribute(const char* name, float defaultValue) const 

+{

+	float f = defaultValue;

+	QueryFloatAttribute(name, &f);

+	return f;

+}

+

+const char* XMLElement::GetText() const

+{

+    if ( FirstChild() && FirstChild()->ToText() ) {

+        return FirstChild()->Value();

+    }

+    return 0;

+}

+

+

+void	XMLElement::SetText( const char* inText )

+{

+	if ( FirstChild() && FirstChild()->ToText() )

+		FirstChild()->SetValue( inText );

+	else {

+		XMLText*	theText = GetDocument()->NewText( inText );

+		InsertFirstChild( theText );

+	}

+}

+

+

+void XMLElement::SetText( int v ) 

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    SetText( buf );

+}

+

+

+void XMLElement::SetText( unsigned v ) 

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    SetText( buf );

+}

+

+

+void XMLElement::SetText(int64_t v)

+{

+	char buf[BUF_SIZE];

+	XMLUtil::ToStr(v, buf, BUF_SIZE);

+	SetText(buf);

+}

+

+

+void XMLElement::SetText( bool v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    SetText( buf );

+}

+

+

+void XMLElement::SetText( float v ) 

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    SetText( buf );

+}

+

+

+void XMLElement::SetText( double v ) 

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    SetText( buf );

+}

+

+

+XMLError XMLElement::QueryIntText( int* ival ) const

+{

+    if ( FirstChild() && FirstChild()->ToText() ) {

+        const char* t = FirstChild()->Value();

+        if ( XMLUtil::ToInt( t, ival ) ) {

+            return XML_SUCCESS;

+        }

+        return XML_CAN_NOT_CONVERT_TEXT;

+    }

+    return XML_NO_TEXT_NODE;

+}

+

+

+XMLError XMLElement::QueryUnsignedText( unsigned* uval ) const

+{

+    if ( FirstChild() && FirstChild()->ToText() ) {

+        const char* t = FirstChild()->Value();

+        if ( XMLUtil::ToUnsigned( t, uval ) ) {

+            return XML_SUCCESS;

+        }

+        return XML_CAN_NOT_CONVERT_TEXT;

+    }

+    return XML_NO_TEXT_NODE;

+}

+

+

+XMLError XMLElement::QueryInt64Text(int64_t* ival) const

+{

+	if (FirstChild() && FirstChild()->ToText()) {

+		const char* t = FirstChild()->Value();

+		if (XMLUtil::ToInt64(t, ival)) {

+			return XML_SUCCESS;

+		}

+		return XML_CAN_NOT_CONVERT_TEXT;

+	}

+	return XML_NO_TEXT_NODE;

+}

+

+

+XMLError XMLElement::QueryBoolText( bool* bval ) const

+{

+    if ( FirstChild() && FirstChild()->ToText() ) {

+        const char* t = FirstChild()->Value();

+        if ( XMLUtil::ToBool( t, bval ) ) {

+            return XML_SUCCESS;

+        }

+        return XML_CAN_NOT_CONVERT_TEXT;

+    }

+    return XML_NO_TEXT_NODE;

+}

+

+

+XMLError XMLElement::QueryDoubleText( double* dval ) const

+{

+    if ( FirstChild() && FirstChild()->ToText() ) {

+        const char* t = FirstChild()->Value();

+        if ( XMLUtil::ToDouble( t, dval ) ) {

+            return XML_SUCCESS;

+        }

+        return XML_CAN_NOT_CONVERT_TEXT;

+    }

+    return XML_NO_TEXT_NODE;

+}

+

+

+XMLError XMLElement::QueryFloatText( float* fval ) const

+{

+    if ( FirstChild() && FirstChild()->ToText() ) {

+        const char* t = FirstChild()->Value();

+        if ( XMLUtil::ToFloat( t, fval ) ) {

+            return XML_SUCCESS;

+        }

+        return XML_CAN_NOT_CONVERT_TEXT;

+    }

+    return XML_NO_TEXT_NODE;

+}

+

+int XMLElement::IntText(int defaultValue) const

+{

+	int i = defaultValue;

+	QueryIntText(&i);

+	return i;

+}

+

+unsigned XMLElement::UnsignedText(unsigned defaultValue) const

+{

+	unsigned i = defaultValue;

+	QueryUnsignedText(&i);

+	return i;

+}

+

+int64_t XMLElement::Int64Text(int64_t defaultValue) const

+{

+	int64_t i = defaultValue;

+	QueryInt64Text(&i);

+	return i;

+}

+

+bool XMLElement::BoolText(bool defaultValue) const

+{

+	bool b = defaultValue;

+	QueryBoolText(&b);

+	return b;

+}

+

+double XMLElement::DoubleText(double defaultValue) const

+{

+	double d = defaultValue;

+	QueryDoubleText(&d);

+	return d;

+}

+

+float XMLElement::FloatText(float defaultValue) const

+{

+	float f = defaultValue;

+	QueryFloatText(&f);

+	return f;

+}

+

+

+XMLAttribute* XMLElement::FindOrCreateAttribute( const char* name )

+{

+    XMLAttribute* last = 0;

+    XMLAttribute* attrib = 0;

+    for( attrib = _rootAttribute;

+            attrib;

+            last = attrib, attrib = attrib->_next ) {

+        if ( XMLUtil::StringEqual( attrib->Name(), name ) ) {

+            break;

+        }

+    }

+    if ( !attrib ) {

+        attrib = CreateAttribute();

+        TIXMLASSERT( attrib );

+        if ( last ) {

+            TIXMLASSERT( last->_next == 0 );

+            last->_next = attrib;

+        }

+        else {

+            TIXMLASSERT( _rootAttribute == 0 );

+            _rootAttribute = attrib;

+        }

+        attrib->SetName( name );

+    }

+    return attrib;

+}

+

+

+void XMLElement::DeleteAttribute( const char* name )

+{

+    XMLAttribute* prev = 0;

+    for( XMLAttribute* a=_rootAttribute; a; a=a->_next ) {

+        if ( XMLUtil::StringEqual( name, a->Name() ) ) {

+            if ( prev ) {

+                prev->_next = a->_next;

+            }

+            else {

+                _rootAttribute = a->_next;

+            }

+            DeleteAttribute( a );

+            break;

+        }

+        prev = a;

+    }

+}

+

+

+char* XMLElement::ParseAttributes( char* p, int* curLineNumPtr )

+{

+    XMLAttribute* prevAttribute = 0;

+

+    // Read the attributes.

+    while( p ) {

+        p = XMLUtil::SkipWhiteSpace( p, curLineNumPtr );

+        if ( !(*p) ) {

+            _document->SetError( XML_ERROR_PARSING_ELEMENT, _parseLineNum, "XMLElement name=%s", Name() );

+            return 0;

+        }

+

+        // attribute.

+        if (XMLUtil::IsNameStartChar( *p ) ) {

+            XMLAttribute* attrib = CreateAttribute();

+            TIXMLASSERT( attrib );

+            attrib->_parseLineNum = _document->_parseCurLineNum;

+

+            int attrLineNum = attrib->_parseLineNum;

+

+            p = attrib->ParseDeep( p, _document->ProcessEntities(), curLineNumPtr );

+            if ( !p || Attribute( attrib->Name() ) ) {

+                DeleteAttribute( attrib );

+                _document->SetError( XML_ERROR_PARSING_ATTRIBUTE, attrLineNum, "XMLElement name=%s", Name() );

+                return 0;

+            }

+            // There is a minor bug here: if the attribute in the source xml

+            // document is duplicated, it will not be detected and the

+            // attribute will be doubly added. However, tracking the 'prevAttribute'

+            // avoids re-scanning the attribute list. Preferring performance for

+            // now, may reconsider in the future.

+            if ( prevAttribute ) {

+                TIXMLASSERT( prevAttribute->_next == 0 );

+                prevAttribute->_next = attrib;

+            }

+            else {

+                TIXMLASSERT( _rootAttribute == 0 );

+                _rootAttribute = attrib;

+            }

+            prevAttribute = attrib;

+        }

+        // end of the tag

+        else if ( *p == '>' ) {

+            ++p;

+            break;

+        }

+        // end of the tag

+        else if ( *p == '/' && *(p+1) == '>' ) {

+            _closingType = CLOSED;

+            return p+2;	// done; sealed element.

+        }

+        else {

+            _document->SetError( XML_ERROR_PARSING_ELEMENT, _parseLineNum, 0 );

+            return 0;

+        }

+    }

+    return p;

+}

+

+void XMLElement::DeleteAttribute( XMLAttribute* attribute )

+{

+    if ( attribute == 0 ) {

+        return;

+    }

+    MemPool* pool = attribute->_memPool;

+    attribute->~XMLAttribute();

+    pool->Free( attribute );

+}

+

+XMLAttribute* XMLElement::CreateAttribute()

+{

+    TIXMLASSERT( sizeof( XMLAttribute ) == _document->_attributePool.ItemSize() );

+    XMLAttribute* attrib = new (_document->_attributePool.Alloc() ) XMLAttribute();

+    TIXMLASSERT( attrib );

+    attrib->_memPool = &_document->_attributePool;

+    attrib->_memPool->SetTracked();

+    return attrib;

+}

+

+//

+//	<ele></ele>

+//	<ele>foo<b>bar</b></ele>

+//

+char* XMLElement::ParseDeep( char* p, StrPair* parentEndTag, int* curLineNumPtr )

+{

+    // Read the element name.

+    p = XMLUtil::SkipWhiteSpace( p, curLineNumPtr );

+

+    // The closing element is the </element> form. It is

+    // parsed just like a regular element then deleted from

+    // the DOM.

+    if ( *p == '/' ) {

+        _closingType = CLOSING;

+        ++p;

+    }

+

+    p = _value.ParseName( p );

+    if ( _value.Empty() ) {

+        return 0;

+    }

+

+    p = ParseAttributes( p, curLineNumPtr );

+    if ( !p || !*p || _closingType != OPEN ) {

+        return p;

+    }

+

+    p = XMLNode::ParseDeep( p, parentEndTag, curLineNumPtr );

+    return p;

+}

+

+

+

+XMLNode* XMLElement::ShallowClone( XMLDocument* doc ) const

+{

+    if ( !doc ) {

+        doc = _document;

+    }

+    XMLElement* element = doc->NewElement( Value() );					// fixme: this will always allocate memory. Intern?

+    for( const XMLAttribute* a=FirstAttribute(); a; a=a->Next() ) {

+        element->SetAttribute( a->Name(), a->Value() );					// fixme: this will always allocate memory. Intern?

+    }

+    return element;

+}

+

+

+bool XMLElement::ShallowEqual( const XMLNode* compare ) const

+{

+    TIXMLASSERT( compare );

+    const XMLElement* other = compare->ToElement();

+    if ( other && XMLUtil::StringEqual( other->Name(), Name() )) {

+

+        const XMLAttribute* a=FirstAttribute();

+        const XMLAttribute* b=other->FirstAttribute();

+

+        while ( a && b ) {

+            if ( !XMLUtil::StringEqual( a->Value(), b->Value() ) ) {

+                return false;

+            }

+            a = a->Next();

+            b = b->Next();

+        }

+        if ( a || b ) {

+            // different count

+            return false;

+        }

+        return true;

+    }

+    return false;

+}

+

+

+bool XMLElement::Accept( XMLVisitor* visitor ) const

+{

+    TIXMLASSERT( visitor );

+    if ( visitor->VisitEnter( *this, _rootAttribute ) ) {

+        for ( const XMLNode* node=FirstChild(); node; node=node->NextSibling() ) {

+            if ( !node->Accept( visitor ) ) {

+                break;

+            }

+        }

+    }

+    return visitor->VisitExit( *this );

+}

+

+

+// --------- XMLDocument ----------- //

+

+// Warning: List must match 'enum XMLError'

+const char* XMLDocument::_errorNames[XML_ERROR_COUNT] = {

+    "XML_SUCCESS",

+    "XML_NO_ATTRIBUTE",

+    "XML_WRONG_ATTRIBUTE_TYPE",

+    "XML_ERROR_FILE_NOT_FOUND",

+    "XML_ERROR_FILE_COULD_NOT_BE_OPENED",

+    "XML_ERROR_FILE_READ_ERROR",

+    "UNUSED_XML_ERROR_ELEMENT_MISMATCH",

+    "XML_ERROR_PARSING_ELEMENT",

+    "XML_ERROR_PARSING_ATTRIBUTE",

+    "UNUSED_XML_ERROR_IDENTIFYING_TAG",

+    "XML_ERROR_PARSING_TEXT",

+    "XML_ERROR_PARSING_CDATA",

+    "XML_ERROR_PARSING_COMMENT",

+    "XML_ERROR_PARSING_DECLARATION",

+    "XML_ERROR_PARSING_UNKNOWN",

+    "XML_ERROR_EMPTY_DOCUMENT",

+    "XML_ERROR_MISMATCHED_ELEMENT",

+    "XML_ERROR_PARSING",

+    "XML_CAN_NOT_CONVERT_TEXT",

+    "XML_NO_TEXT_NODE"

+};

+

+

+XMLDocument::XMLDocument( bool processEntities, Whitespace whitespaceMode ) :

+    XMLNode( 0 ),

+    _writeBOM( false ),

+    _processEntities( processEntities ),

+    _errorID(XML_SUCCESS),

+    _whitespaceMode( whitespaceMode ),

+    _errorStr(),

+    _errorLineNum( 0 ),

+    _charBuffer( 0 ),

+    _parseCurLineNum( 0 ),

+    _unlinked(),

+    _elementPool(),

+    _attributePool(),

+    _textPool(),

+    _commentPool()

+{

+    // avoid VC++ C4355 warning about 'this' in initializer list (C4355 is off by default in VS2012+)

+    _document = this;

+}

+

+

+XMLDocument::~XMLDocument()

+{

+    Clear();

+}

+

+

+void XMLDocument::MarkInUse(XMLNode* node)

+{

+	TIXMLASSERT(node);

+	TIXMLASSERT(node->_parent == 0);

+

+	for (int i = 0; i < _unlinked.Size(); ++i) {

+		if (node == _unlinked[i]) {

+			_unlinked.SwapRemove(i);

+			break;

+		}

+	}

+}

+

+void XMLDocument::Clear()

+{

+    DeleteChildren();

+	while( _unlinked.Size()) {

+		DeleteNode(_unlinked[0]);	// Will remove from _unlinked as part of delete.

+	}

+

+#ifdef TINYXML2_DEBUG

+    const bool hadError = Error();

+#endif

+    ClearError();

+

+    delete [] _charBuffer;

+    _charBuffer = 0;

+

+#if 0

+    _textPool.Trace( "text" );

+    _elementPool.Trace( "element" );

+    _commentPool.Trace( "comment" );

+    _attributePool.Trace( "attribute" );

+#endif

+    

+#ifdef TINYXML2_DEBUG

+    if ( !hadError ) {

+        TIXMLASSERT( _elementPool.CurrentAllocs()   == _elementPool.Untracked() );

+        TIXMLASSERT( _attributePool.CurrentAllocs() == _attributePool.Untracked() );

+        TIXMLASSERT( _textPool.CurrentAllocs()      == _textPool.Untracked() );

+        TIXMLASSERT( _commentPool.CurrentAllocs()   == _commentPool.Untracked() );

+    }

+#endif

+}

+

+

+void XMLDocument::DeepCopy(XMLDocument* target) const

+{

+	TIXMLASSERT(target);

+    if (target == this) {

+        return; // technically success - a no-op.

+    }

+

+	target->Clear();

+	for (const XMLNode* node = this->FirstChild(); node; node = node->NextSibling()) {

+		target->InsertEndChild(node->DeepClone(target));

+	}

+}

+

+XMLElement* XMLDocument::NewElement( const char* name )

+{

+    XMLElement* ele = CreateUnlinkedNode<XMLElement>( _elementPool );

+    ele->SetName( name );

+    return ele;

+}

+

+

+XMLComment* XMLDocument::NewComment( const char* str )

+{

+    XMLComment* comment = CreateUnlinkedNode<XMLComment>( _commentPool );

+    comment->SetValue( str );

+    return comment;

+}

+

+

+XMLText* XMLDocument::NewText( const char* str )

+{

+    XMLText* text = CreateUnlinkedNode<XMLText>( _textPool );

+    text->SetValue( str );

+    return text;

+}

+

+

+XMLDeclaration* XMLDocument::NewDeclaration( const char* str )

+{

+    XMLDeclaration* dec = CreateUnlinkedNode<XMLDeclaration>( _commentPool );

+    dec->SetValue( str ? str : "xml version=\"1.0\" encoding=\"UTF-8\"" );

+    return dec;

+}

+

+

+XMLUnknown* XMLDocument::NewUnknown( const char* str )

+{

+    XMLUnknown* unk = CreateUnlinkedNode<XMLUnknown>( _commentPool );

+    unk->SetValue( str );

+    return unk;

+}

+

+static FILE* callfopen( const char* filepath, const char* mode )

+{

+    TIXMLASSERT( filepath );

+    TIXMLASSERT( mode );

+#if defined(_MSC_VER) && (_MSC_VER >= 1400 ) && (!defined WINCE)

+    FILE* fp = 0;

+    errno_t err = fopen_s( &fp, filepath, mode );

+    if ( err ) {

+        return 0;

+    }

+#else

+    FILE* fp = fopen( filepath, mode );

+#endif

+    return fp;

+}

+    

+void XMLDocument::DeleteNode( XMLNode* node )	{

+    TIXMLASSERT( node );

+    TIXMLASSERT(node->_document == this );

+    if (node->_parent) {

+        node->_parent->DeleteChild( node );

+    }

+    else {

+        // Isn't in the tree.

+        // Use the parent delete.

+        // Also, we need to mark it tracked: we 'know'

+        // it was never used.

+        node->_memPool->SetTracked();

+        // Call the static XMLNode version:

+        XMLNode::DeleteNode(node);

+    }

+}

+

+

+XMLError XMLDocument::LoadFile( const char* filename )

+{

+    Clear();

+    FILE* fp = callfopen( filename, "rb" );

+    if ( !fp ) {

+        SetError( XML_ERROR_FILE_NOT_FOUND, 0, "filename=%s", filename ? filename : "<null>");

+        return _errorID;

+    }

+    LoadFile( fp );

+    fclose( fp );

+    return _errorID;

+}

+

+// This is likely overengineered template art to have a check that unsigned long value incremented

+// by one still fits into size_t. If size_t type is larger than unsigned long type

+// (x86_64-w64-mingw32 target) then the check is redundant and gcc and clang emit

+// -Wtype-limits warning. This piece makes the compiler select code with a check when a check

+// is useful and code with no check when a check is redundant depending on how size_t and unsigned long

+// types sizes relate to each other.

+template

+<bool = (sizeof(unsigned long) >= sizeof(size_t))>

+struct LongFitsIntoSizeTMinusOne {

+    static bool Fits( unsigned long value )

+    {

+        return value < (size_t)-1;

+    }

+};

+

+template <>

+struct LongFitsIntoSizeTMinusOne<false> {

+    static bool Fits( unsigned long )

+    {

+        return true;

+    }

+};

+

+XMLError XMLDocument::LoadFile( FILE* fp )

+{

+    Clear();

+

+    fseek( fp, 0, SEEK_SET );

+    if ( fgetc( fp ) == EOF && ferror( fp ) != 0 ) {

+        SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );

+        return _errorID;

+    }

+

+    fseek( fp, 0, SEEK_END );

+    const long filelength = ftell( fp );

+    fseek( fp, 0, SEEK_SET );

+    if ( filelength == -1L ) {

+        SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );

+        return _errorID;

+    }

+    TIXMLASSERT( filelength >= 0 );

+

+    if ( !LongFitsIntoSizeTMinusOne<>::Fits( filelength ) ) {

+        // Cannot handle files which won't fit in buffer together with null terminator

+        SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );

+        return _errorID;

+    }

+

+    if ( filelength == 0 ) {

+        SetError( XML_ERROR_EMPTY_DOCUMENT, 0, 0 );

+        return _errorID;

+    }

+

+    const size_t size = filelength;

+    TIXMLASSERT( _charBuffer == 0 );

+    _charBuffer = new char[size+1];

+    size_t read = fread( _charBuffer, 1, size, fp );

+    if ( read != size ) {

+        SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );

+        return _errorID;

+    }

+

+    _charBuffer[size] = 0;

+

+    Parse();

+    return _errorID;

+}

+

+

+XMLError XMLDocument::SaveFile( const char* filename, bool compact )

+{

+    FILE* fp = callfopen( filename, "w" );

+    if ( !fp ) {

+        SetError( XML_ERROR_FILE_COULD_NOT_BE_OPENED, 0, "filename=%s", filename ? filename : "<null>");

+        return _errorID;

+    }

+    SaveFile(fp, compact);

+    fclose( fp );

+    return _errorID;

+}

+

+

+XMLError XMLDocument::SaveFile( FILE* fp, bool compact )

+{

+    // Clear any error from the last save, otherwise it will get reported

+    // for *this* call.

+    ClearError();

+    XMLPrinter stream( fp, compact );

+    Print( &stream );

+    return _errorID;

+}

+

+

+XMLError XMLDocument::Parse( const char* p, size_t len )

+{

+    Clear();

+

+    if ( len == 0 || !p || !*p ) {

+        SetError( XML_ERROR_EMPTY_DOCUMENT, 0, 0 );

+        return _errorID;

+    }

+    if ( len == (size_t)(-1) ) {

+        len = strlen( p );

+    }

+    TIXMLASSERT( _charBuffer == 0 );

+    _charBuffer = new char[ len+1 ];

+    memcpy( _charBuffer, p, len );

+    _charBuffer[len] = 0;

+

+    Parse();

+    if ( Error() ) {

+        // clean up now essentially dangling memory.

+        // and the parse fail can put objects in the

+        // pools that are dead and inaccessible.

+        DeleteChildren();

+        _elementPool.Clear();

+        _attributePool.Clear();

+        _textPool.Clear();

+        _commentPool.Clear();

+    }

+    return _errorID;

+}

+

+

+void XMLDocument::Print( XMLPrinter* streamer ) const

+{

+    if ( streamer ) {

+        Accept( streamer );

+    }

+    else {

+        XMLPrinter stdoutStreamer( stdout );

+        Accept( &stdoutStreamer );

+    }

+}

+

+

+void XMLDocument::SetError( XMLError error, int lineNum, const char* format, ... )

+{

+    TIXMLASSERT( error >= 0 && error < XML_ERROR_COUNT );

+    _errorID = error;

+    _errorLineNum = lineNum;

+	_errorStr.Reset();

+

+    size_t BUFFER_SIZE = 1000;

+    char* buffer = new char[BUFFER_SIZE];

+

+    TIXML_SNPRINTF(buffer, BUFFER_SIZE, "Error=%s ErrorID=%d (0x%x) Line number=%d", ErrorIDToName(error), int(error), int(error), lineNum);

+

+	if (format) {

+		size_t len = strlen(buffer);

+		TIXML_SNPRINTF(buffer + len, BUFFER_SIZE - len, ": ");

+		len = strlen(buffer);

+

+		va_list va;

+		va_start(va, format);

+		TIXML_VSNPRINTF(buffer + len, BUFFER_SIZE - len, format, va);

+		va_end(va);

+	}

+	_errorStr.SetStr(buffer);

+	delete[] buffer;

+}

+

+

+/*static*/ const char* XMLDocument::ErrorIDToName(XMLError errorID)

+{

+	TIXMLASSERT( errorID >= 0 && errorID < XML_ERROR_COUNT );

+    const char* errorName = _errorNames[errorID];

+    TIXMLASSERT( errorName && errorName[0] );

+    return errorName;

+}

+

+const char* XMLDocument::ErrorStr() const 

+{

+	return _errorStr.Empty() ? "" : _errorStr.GetStr();

+}

+

+

+void XMLDocument::PrintError() const

+{

+    printf("%s\n", ErrorStr());

+}

+

+const char* XMLDocument::ErrorName() const

+{

+    return ErrorIDToName(_errorID);

+}

+

+void XMLDocument::Parse()

+{

+    TIXMLASSERT( NoChildren() ); // Clear() must have been called previously

+    TIXMLASSERT( _charBuffer );

+    _parseCurLineNum = 1;

+    _parseLineNum = 1;

+    char* p = _charBuffer;

+    p = XMLUtil::SkipWhiteSpace( p, &_parseCurLineNum );

+    p = const_cast<char*>( XMLUtil::ReadBOM( p, &_writeBOM ) );

+    if ( !*p ) {

+        SetError( XML_ERROR_EMPTY_DOCUMENT, 0, 0 );

+        return;

+    }

+    ParseDeep(p, 0, &_parseCurLineNum );

+}

+

+XMLPrinter::XMLPrinter( FILE* file, bool compact, int depth ) :

+    _elementJustOpened( false ),

+    _stack(),

+    _firstElement( true ),

+    _fp( file ),

+    _depth( depth ),

+    _textDepth( -1 ),

+    _processEntities( true ),

+    _compactMode( compact ),

+    _buffer()

+{

+    for( int i=0; i<ENTITY_RANGE; ++i ) {

+        _entityFlag[i] = false;

+        _restrictedEntityFlag[i] = false;

+    }

+    for( int i=0; i<NUM_ENTITIES; ++i ) {

+        const char entityValue = entities[i].value;

+        const unsigned char flagIndex = (unsigned char)entityValue;

+        TIXMLASSERT( flagIndex < ENTITY_RANGE );

+        _entityFlag[flagIndex] = true;

+    }

+    _restrictedEntityFlag[(unsigned char)'&'] = true;

+    _restrictedEntityFlag[(unsigned char)'<'] = true;

+    _restrictedEntityFlag[(unsigned char)'>'] = true;	// not required, but consistency is nice

+    _buffer.Push( 0 );

+}

+

+

+void XMLPrinter::Print( const char* format, ... )

+{

+    va_list     va;

+    va_start( va, format );

+

+    if ( _fp ) {

+        vfprintf( _fp, format, va );

+    }

+    else {

+        const int len = TIXML_VSCPRINTF( format, va );

+        // Close out and re-start the va-args

+        va_end( va );

+        TIXMLASSERT( len >= 0 );

+        va_start( va, format );

+        TIXMLASSERT( _buffer.Size() > 0 && _buffer[_buffer.Size() - 1] == 0 );

+        char* p = _buffer.PushArr( len ) - 1;	// back up over the null terminator.

+		TIXML_VSNPRINTF( p, len+1, format, va );

+    }

+    va_end( va );

+}

+

+

+void XMLPrinter::Write( const char* data, size_t size )

+{

+    if ( _fp ) {

+        fwrite ( data , sizeof(char), size, _fp);

+    }

+    else {

+        char* p = _buffer.PushArr( static_cast<int>(size) ) - 1;   // back up over the null terminator.

+        memcpy( p, data, size );

+        p[size] = 0;

+    }

+}

+

+

+void XMLPrinter::Putc( char ch )

+{

+    if ( _fp ) {

+        fputc ( ch, _fp);

+    }

+    else {

+        char* p = _buffer.PushArr( sizeof(char) ) - 1;   // back up over the null terminator.

+        p[0] = ch;

+        p[1] = 0;

+    }

+}

+

+

+void XMLPrinter::PrintSpace( int depth )

+{

+    for( int i=0; i<depth; ++i ) {

+        Write( "    " );

+    }

+}

+

+

+void XMLPrinter::PrintString( const char* p, bool restricted )

+{

+    // Look for runs of bytes between entities to print.

+    const char* q = p;

+

+    if ( _processEntities ) {

+        const bool* flag = restricted ? _restrictedEntityFlag : _entityFlag;

+        while ( *q ) {

+            TIXMLASSERT( p <= q );

+            // Remember, char is sometimes signed. (How many times has that bitten me?)

+            if ( *q > 0 && *q < ENTITY_RANGE ) {

+                // Check for entities. If one is found, flush

+                // the stream up until the entity, write the

+                // entity, and keep looking.

+                if ( flag[(unsigned char)(*q)] ) {

+                    while ( p < q ) {

+                        const size_t delta = q - p;

+                        const int toPrint = ( INT_MAX < delta ) ? INT_MAX : (int)delta;

+                        Write( p, toPrint );

+                        p += toPrint;

+                    }

+                    bool entityPatternPrinted = false;

+                    for( int i=0; i<NUM_ENTITIES; ++i ) {

+                        if ( entities[i].value == *q ) {

+                            Putc( '&' );

+                            Write( entities[i].pattern, entities[i].length );

+                            Putc( ';' );

+                            entityPatternPrinted = true;

+                            break;

+                        }

+                    }

+                    if ( !entityPatternPrinted ) {

+                        // TIXMLASSERT( entityPatternPrinted ) causes gcc -Wunused-but-set-variable in release

+                        TIXMLASSERT( false );

+                    }

+                    ++p;

+                }

+            }

+            ++q;

+            TIXMLASSERT( p <= q );

+        }

+    }

+    // Flush the remaining string. This will be the entire

+    // string if an entity wasn't found.

+    TIXMLASSERT( p <= q );

+    if ( !_processEntities || ( p < q ) ) {

+        const size_t delta = q - p;

+        const int toPrint = ( INT_MAX < delta ) ? INT_MAX : (int)delta;

+        Write( p, toPrint );

+    }

+}

+

+

+void XMLPrinter::PushHeader( bool writeBOM, bool writeDec )

+{

+    if ( writeBOM ) {

+        static const unsigned char bom[] = { TIXML_UTF_LEAD_0, TIXML_UTF_LEAD_1, TIXML_UTF_LEAD_2, 0 };

+        Write( reinterpret_cast< const char* >( bom ) );

+    }

+    if ( writeDec ) {

+        PushDeclaration( "xml version=\"1.0\"" );

+    }

+}

+

+

+void XMLPrinter::OpenElement( const char* name, bool compactMode )

+{

+    SealElementIfJustOpened();

+    _stack.Push( name );

+

+    if ( _textDepth < 0 && !_firstElement && !compactMode ) {

+        Putc( '\n' );

+    }

+    if ( !compactMode ) {

+        PrintSpace( _depth );

+    }

+

+    Write ( "<" );

+    Write ( name );

+

+    _elementJustOpened = true;

+    _firstElement = false;

+    ++_depth;

+}

+

+

+void XMLPrinter::PushAttribute( const char* name, const char* value )

+{

+    TIXMLASSERT( _elementJustOpened );

+    Putc ( ' ' );

+    Write( name );

+    Write( "=\"" );

+    PrintString( value, false );

+    Putc ( '\"' );

+}

+

+

+void XMLPrinter::PushAttribute( const char* name, int v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    PushAttribute( name, buf );

+}

+

+

+void XMLPrinter::PushAttribute( const char* name, unsigned v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    PushAttribute( name, buf );

+}

+

+

+void XMLPrinter::PushAttribute(const char* name, int64_t v)

+{

+	char buf[BUF_SIZE];

+	XMLUtil::ToStr(v, buf, BUF_SIZE);

+	PushAttribute(name, buf);

+}

+

+

+void XMLPrinter::PushAttribute( const char* name, bool v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    PushAttribute( name, buf );

+}

+

+

+void XMLPrinter::PushAttribute( const char* name, double v )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( v, buf, BUF_SIZE );

+    PushAttribute( name, buf );

+}

+

+

+void XMLPrinter::CloseElement( bool compactMode )

+{

+    --_depth;

+    const char* name = _stack.Pop();

+

+    if ( _elementJustOpened ) {

+        Write( "/>" );

+    }

+    else {

+        if ( _textDepth < 0 && !compactMode) {

+            Putc( '\n' );

+            PrintSpace( _depth );

+        }

+        Write ( "</" );

+        Write ( name );

+        Write ( ">" );

+    }

+

+    if ( _textDepth == _depth ) {

+        _textDepth = -1;

+    }

+    if ( _depth == 0 && !compactMode) {

+        Putc( '\n' );

+    }

+    _elementJustOpened = false;

+}

+

+

+void XMLPrinter::SealElementIfJustOpened()

+{

+    if ( !_elementJustOpened ) {

+        return;

+    }

+    _elementJustOpened = false;

+    Putc( '>' );

+}

+

+

+void XMLPrinter::PushText( const char* text, bool cdata )

+{

+    _textDepth = _depth-1;

+

+    SealElementIfJustOpened();

+    if ( cdata ) {

+        Write( "<![CDATA[" );

+        Write( text );

+        Write( "]]>" );

+    }

+    else {

+        PrintString( text, true );

+    }

+}

+

+void XMLPrinter::PushText( int64_t value )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( value, buf, BUF_SIZE );

+    PushText( buf, false );

+}

+

+void XMLPrinter::PushText( int value )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( value, buf, BUF_SIZE );

+    PushText( buf, false );

+}

+

+

+void XMLPrinter::PushText( unsigned value )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( value, buf, BUF_SIZE );

+    PushText( buf, false );

+}

+

+

+void XMLPrinter::PushText( bool value )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( value, buf, BUF_SIZE );

+    PushText( buf, false );

+}

+

+

+void XMLPrinter::PushText( float value )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( value, buf, BUF_SIZE );

+    PushText( buf, false );

+}

+

+

+void XMLPrinter::PushText( double value )

+{

+    char buf[BUF_SIZE];

+    XMLUtil::ToStr( value, buf, BUF_SIZE );

+    PushText( buf, false );

+}

+

+

+void XMLPrinter::PushComment( const char* comment )

+{

+    SealElementIfJustOpened();

+    if ( _textDepth < 0 && !_firstElement && !_compactMode) {

+        Putc( '\n' );

+        PrintSpace( _depth );

+    }

+    _firstElement = false;

+

+    Write( "<!--" );

+    Write( comment );

+    Write( "-->" );

+}

+

+

+void XMLPrinter::PushDeclaration( const char* value )

+{

+    SealElementIfJustOpened();

+    if ( _textDepth < 0 && !_firstElement && !_compactMode) {

+        Putc( '\n' );

+        PrintSpace( _depth );

+    }

+    _firstElement = false;

+

+    Write( "<?" );

+    Write( value );

+    Write( "?>" );

+}

+

+

+void XMLPrinter::PushUnknown( const char* value )

+{

+    SealElementIfJustOpened();

+    if ( _textDepth < 0 && !_firstElement && !_compactMode) {

+        Putc( '\n' );

+        PrintSpace( _depth );

+    }

+    _firstElement = false;

+

+    Write( "<!" );

+    Write( value );

+    Putc( '>' );

+}

+

+

+bool XMLPrinter::VisitEnter( const XMLDocument& doc )

+{

+    _processEntities = doc.ProcessEntities();

+    if ( doc.HasBOM() ) {

+        PushHeader( true, false );

+    }

+    return true;

+}

+

+

+bool XMLPrinter::VisitEnter( const XMLElement& element, const XMLAttribute* attribute )

+{

+    const XMLElement* parentElem = 0;

+    if ( element.Parent() ) {

+        parentElem = element.Parent()->ToElement();

+    }

+    const bool compactMode = parentElem ? CompactMode( *parentElem ) : _compactMode;

+    OpenElement( element.Name(), compactMode );

+    while ( attribute ) {

+        PushAttribute( attribute->Name(), attribute->Value() );

+        attribute = attribute->Next();

+    }

+    return true;

+}

+

+

+bool XMLPrinter::VisitExit( const XMLElement& element )

+{

+    CloseElement( CompactMode(element) );

+    return true;

+}

+

+

+bool XMLPrinter::Visit( const XMLText& text )

+{

+    PushText( text.Value(), text.CData() );

+    return true;

+}

+

+

+bool XMLPrinter::Visit( const XMLComment& comment )

+{

+    PushComment( comment.Value() );

+    return true;

+}

+

+bool XMLPrinter::Visit( const XMLDeclaration& declaration )

+{

+    PushDeclaration( declaration.Value() );

+    return true;

+}

+

+

+bool XMLPrinter::Visit( const XMLUnknown& unknown )

+{

+    PushUnknown( unknown.Value() );

+    return true;

+}

+

+}   // namespace tinyxml2

+

diff --git a/hw6/src/transformation3d.cpp b/hw6/src/transformation3d.cpp
new file mode 100644
index 0000000..bde9caa
--- /dev/null
+++ b/hw6/src/transformation3d.cpp
@@ -0,0 +1,174 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "transformation3d.h"
+
+
+//////////////////
+// Constructors //
+//////////////////
+transformation3d::transformation3d(void)
+{
+  _translation = vec3d();
+  _transformation = mat3d(1.0f);
+  _inverseTransformation = mat3d(1.0f);
+}
+
+
+transformation3d::transformation3d(const vec3d& translation, const mat3d& transformation, const mat3d& inverseTransformation)
+{
+  _translation = translation;
+  _transformation = transformation;
+  _inverseTransformation = inverseTransformation;
+}
+
+
+transformation3d::transformation3d(const transformation3d& t)
+{
+  _translation = t._translation;
+  _transformation = t._transformation;
+  _inverseTransformation = t._inverseTransformation;
+}
+
+
+//////////////
+// Operator //
+//////////////
+transformation3d& transformation3d::operator=(const transformation3d& t)
+{
+  _assign(t);
+  return *this;
+}
+
+
+transformation3d transformation3d::operator*(const transformation3d& t) const
+{
+  return transformation3d( transformPoint(t._translation),
+			   _transformation * t._transformation,
+			   t._inverseTransformation * _inverseTransformation);
+}
+
+
+transformation3d& transformation3d::operator*=(const transformation3d& t)
+{
+  *this = *this * t;
+  return *this;
+}
+
+
+//////////////
+// Mutators //
+//////////////
+transformation3d& transformation3d::invert(void)
+{
+  _translation = _inverseTransformation * (-_translation);
+  swap(_transformation, _inverseTransformation);
+  return *this;
+}
+
+/////////////
+// Methods //
+/////////////
+vec3d transformation3d::transformPoint(const vec3d& p) const
+{
+  // first transform, then translate
+  vec3d transformed = _transformation * p;
+  transformed += _translation;
+  
+  // Done.
+  return transformed;
+}
+
+
+vec3d transformation3d::transformDirection(const vec3d& d) const
+{
+  // Only apply transformation
+  vec3d transformed = _transformation * d;
+
+  // Done.
+  return transformed.normalize();
+}
+
+
+vec3d transformation3d::transformNormal(const vec3d& n) const
+{
+  // Don't apply translation.
+  // n' = (_transformation^T)^-1 * n
+  // n'^T = n^T * _transformation^-1
+  // n'^T = n^T * _inverseTransformation
+  vec3d transformed = n * _inverseTransformation;
+  
+  // Done.
+  return transformed.normalize();
+}
+
+
+vec3d transformation3d::inverseTransformPoint(const vec3d& p) const
+{
+  // for undo translation, then invert the transformation
+  vec3d transformed = p - _translation;
+  transformed = _inverseTransformation * transformed;
+
+  // Done.
+  return transformed;
+}
+
+
+vec3d transformation3d::inverseTransformDirection(const vec3d& d) const
+{
+  // Only invert the transformation
+  vec3d transformed = _inverseTransformation * d;
+
+  // Done.
+  return transformed.normalize();
+}
+
+
+vec3d transformation3d::inverseTransformNormal(const vec3d& n) const
+{
+  // Don't apply translation. Undo (transformation^T)^-1
+  vec3d transformed = n * _transformation;
+
+  // Done.
+  return transformed.normalize();
+}
+
+
+///////////////////////
+// Protected Methods //
+///////////////////////
+void transformation3d::_swap(transformation3d& t)
+{
+  std::swap(_translation, t._translation);
+  std::swap(_transformation, t._transformation);
+  std::swap(_inverseTransformation, t._inverseTransformation);
+}
+
+
+void transformation3d::_assign(const transformation3d& t)
+{
+  // avoid copying when self-assigning
+  if(&t == this) return;
+
+  // Copy
+  _translation = t._translation;
+  _transformation = t._transformation;
+  _inverseTransformation = t._inverseTransformation;
+
+  // Done.
+}
+
+
+void transformation3d::_print(std::ostream& s) const
+{
+  s << "{";
+  s << "Translation = " << _translation << ", ";
+  s << "Transformation = " << _transformation << ", ";
+  s << "Inverse Trans. = " << _inverseTransformation;
+  s << "}";
+}
diff --git a/hw6/src/translation3d.cpp b/hw6/src/translation3d.cpp
new file mode 100644
index 0000000..a8facd3
--- /dev/null
+++ b/hw6/src/translation3d.cpp
@@ -0,0 +1,29 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "translation3d.h"
+
+//////////////////
+// Constructors //
+//////////////////
+translation3d::translation3d(void) : transformation3d()
+{
+  // Do Nothing
+}
+
+
+translation3d::translation3d(const vec3d& translation) : transformation3d()
+{
+  _translation = translation;
+}
+
+
+translation3d::translation3d(const translation3d& t) : transformation3d(t)
+{
+  // Do Nothing
+}
diff --git a/hw6/src/triangle.cpp b/hw6/src/triangle.cpp
new file mode 100644
index 0000000..940363e
--- /dev/null
+++ b/hw6/src/triangle.cpp
@@ -0,0 +1,465 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include <cassert>
+#include <algorithm>
+
+#include "triangle.h"
+#include "constants.h"
+
+//////////////////
+// Constructors //
+//////////////////
+triangle::triangle(void)
+{
+  _vertex_list = nullptr;
+  _normal_list = nullptr;
+  _textureCoord_list = nullptr;
+}
+
+
+//////////////////////
+// Copy Constructor //
+//////////////////////
+triangle::triangle(const triangle& t)
+  : triangle()
+{
+  // share ptr to list
+  _vertex_list = t._vertex_list;
+  _normal_list = t._normal_list;
+  _textureCoord_list = t._textureCoord_list;
+
+  // copy indices
+  _vertex_idx = t._vertex_idx;
+  _normal_idx = t._normal_idx;
+  _textureCoord_idx = t._textureCoord_idx;
+}
+
+
+//////////////////////
+// Move Constructor //
+//////////////////////
+triangle::triangle(triangle&& t)
+  : triangle()
+{
+  // swap list (no need to increment ref-count)
+  std::swap(_vertex_list, t._vertex_list);
+  std::swap(_normal_list, t._normal_list);
+  std::swap(_textureCoord_list, t._textureCoord_list);
+
+  // copy indices
+  _vertex_idx = t._vertex_idx;
+  _normal_idx = t._normal_idx;
+  _textureCoord_idx = t._textureCoord_idx;
+}
+
+
+//////////////////////////
+// General Constructors //
+//////////////////////////
+triangle::triangle(const vec3d& v1, const vec3d& v2, const vec3d& v3)
+  : triangle()
+{
+  // create a list of three vertices
+  auto vertex_list = std::make_shared<std::vector<vec3d>>(3);
+  _vertex_list = vertex_list;
+
+  // copy values
+  (*vertex_list)[0] = v1;
+  (*vertex_list)[1] = v2;
+  (*vertex_list)[2] = v3;
+
+  // set indices
+  _vertex_idx = {0,1,2};
+}
+
+
+triangle::triangle(size_t v1_idx, size_t v2_idx, size_t v3_idx, const std::shared_ptr<const std::vector<vec3d>>& vertex_list)
+  : triangle()
+{
+  // share vertex list
+  _vertex_list = vertex_list;
+
+  // copy indices
+  _vertex_idx[0] = v1_idx;
+  _vertex_idx[1] = v2_idx;
+  _vertex_idx[2] = v3_idx;
+}
+
+
+
+triangle::triangle(const vec3d& v1, const vec3d& v2, const vec3d& v3,
+		  const vec3d& n1, const vec3d& n2, const vec3d& n3)
+  : triangle(v1, v2, v3)
+{
+  // create a list of three normals
+  auto normal_list = std::make_shared<std::vector<vec3d>>(3);
+  _normal_list = normal_list;
+
+  // copy values
+  (*normal_list)[0] = n1;
+  (*normal_list)[1] = n2;
+  (*normal_list)[2] = n3;
+
+  // set indices
+  _normal_idx = {0,1,2};
+}
+
+
+triangle::triangle(size_t v1_idx, size_t v2_idx, size_t v3_idx, const std::shared_ptr<const std::vector<vec3d>>& vertex_list,
+		     size_t n1_idx, size_t n2_idx, size_t n3_idx, const std::shared_ptr<const std::vector<vec3d>>& normal_list)
+  : triangle(v1_idx, v2_idx, v3_idx, vertex_list)
+{
+  // share normal list
+  _normal_list = normal_list;
+
+  // copy indices
+  _normal_idx[0] = n1_idx;
+  _normal_idx[1] = n2_idx;
+  _normal_idx[2] = n3_idx;
+}
+
+
+
+triangle::triangle(const vec3d& v1, const vec3d& v2, const vec3d& v3,
+		   const vec2d& t1, const vec2d& t2, const vec2d& t3)
+  : triangle(v1, v2, v3)
+{
+  // create a list of three texture coordinates
+  auto textureCoord_list = std::make_shared<std::vector<vec2d>>(3);
+  _textureCoord_list = textureCoord_list;
+
+  // copy values
+  (*textureCoord_list)[0] = t1;
+  (*textureCoord_list)[1] = t2;
+  (*textureCoord_list)[2] = t3;
+
+  // set indices
+  _textureCoord_idx = {0,1,2};
+}
+
+
+triangle::triangle(size_t v1_idx, size_t v2_idx, size_t v3_idx, const std::shared_ptr<const std::vector<vec3d>>& vertex_list,
+		   size_t t1_idx, size_t t2_idx, size_t t3_idx, const std::shared_ptr<const std::vector<vec2d>>& texcoord_list)
+  : triangle(v1_idx, v2_idx, v3_idx, vertex_list)
+{
+  // share normal list
+  _textureCoord_list = texcoord_list;
+
+  // copy indices
+  _textureCoord_idx[0] = t1_idx;
+  _textureCoord_idx[1] = t2_idx;
+  _textureCoord_idx[2] = t3_idx;
+}
+
+
+
+triangle::triangle(const vec3d& v1, const vec3d& v2, const vec3d& v3,
+		   const vec3d& n1, const vec3d& n2, const vec3d& n3,
+		   const vec2d& t1, const vec2d& t2, const vec2d& t3)
+  : triangle(v1, v2, v3, n1, n2, n3)
+{
+  // create a list of three texture coordinates
+  auto textureCoord_list = std::make_shared<std::vector<vec2d>>(3);
+  _textureCoord_list = textureCoord_list;
+
+  // copy values
+  (*textureCoord_list)[0] = t1;
+  (*textureCoord_list)[1] = t2;
+  (*textureCoord_list)[2] = t3;
+
+  // set indices
+  _textureCoord_idx = {0,1,2};
+}
+
+
+triangle::triangle(size_t v1_idx, size_t v2_idx, size_t v3_idx, const std::shared_ptr<const std::vector<vec3d>>& vertex_list,
+		   size_t n1_idx, size_t n2_idx, size_t n3_idx, const std::shared_ptr<const std::vector<vec3d>>& normal_list,
+		   size_t t1_idx, size_t t2_idx, size_t t3_idx, const std::shared_ptr<const std::vector<vec2d>>& texcoord_list)
+  : triangle(v1_idx, v2_idx, v3_idx, vertex_list,
+	     n1_idx, n2_idx, n3_idx, normal_list)
+{
+  // share normal list
+  _textureCoord_list = texcoord_list;
+
+  // copy indices
+  _textureCoord_idx[0] = t1_idx;
+  _textureCoord_idx[1] = t2_idx;
+  _textureCoord_idx[2] = t3_idx;
+}
+
+
+
+////////////////
+// Inspectors //
+////////////////
+const vec3d& triangle::vertex(size_t index) const
+{
+  // bounds check
+  assert(_vertex_list && index < 3);
+
+  // Done.
+  return (*_vertex_list)[_vertex_idx[index]];
+}
+
+
+const vec3d& triangle::normal(size_t index) const
+{
+  // bounds check
+  assert(_normal_list && index < 3);
+  
+  // Done.
+  return (*_normal_list)[_normal_idx[index]];
+}
+
+
+const vec2d& triangle::textureCoordinate(size_t index) const
+{
+  // bounds check
+  assert(_textureCoord_list && index < 3);
+
+  // Done.
+  return (*_textureCoord_list)[_textureCoord_idx[index]];
+}
+
+
+bool triangle::hasPerVertexNormals(void) const
+{
+  return (bool)(_normal_list);
+}
+
+
+bool triangle::hasPerVertexTextureCoordinates(void) const
+{
+  return (bool)(_textureCoord_list);
+}
+
+
+///////////////
+// Operators //
+///////////////
+triangle& triangle::operator=(const triangle& t)
+{
+  _assign(t);
+  return *this;
+}
+
+
+triangle& triangle::operator=(triangle&& t)
+{
+  // swap list (no need to increment ref-count)
+  std::swap(_vertex_list, t._vertex_list);
+  std::swap(_normal_list, t._normal_list);
+  std::swap(_textureCoord_list, t._textureCoord_list);
+
+  // copy indices
+  _vertex_idx = t._vertex_idx;
+  _normal_idx = t._normal_idx;
+  _textureCoord_idx = t._textureCoord_idx;
+
+  // Done.
+  return *this;
+}
+
+
+/////////////
+// Methods //
+/////////////
+bool triangle::intersect(const ray& r, vec3d& barycentricCoord, float& t) const
+{
+  // Ray-Triangle intersection [Moller and Trumbore 1997]
+  //
+  // [t           ]                1             [ ((r.origin-v0) x (v1-v0)).(v2-v0) ]
+  // [barycenter.y] = -------------------------- [ (r.dir x (v2-v0)).(r.origin-v0)   ]
+  // [barycenter.z]   ((r.dir x (v2-vo)).(v1-v0) [ ((r.origin-v0) x (v1-v0)).r.dir   ]
+  //
+  
+  // compute denominator
+  vec3d e1 = vertex(1) - vertex(0);
+  vec3d e2 = vertex(2) - vertex(0);
+  vec3d p = r.direction().cross(e2);
+  float denom = p.dot(e1);
+
+  // check if parallel (denominator == 0)
+  if(fabs(denom) < EPSILON) return false;
+  denom = 1.0f / denom;
+
+  // compute barycentricCoord.y
+  vec3d diff = r.origin() - vertex(0);
+  barycentricCoord.y = denom * p.dot(diff);
+
+  // check if barycenter.y inside triangle
+  if(barycentricCoord.y < -EPSILON || barycentricCoord.y > 1.0f+EPSILON) return false;
+
+  // compute barycentricCoord.z
+  vec3d diffXe1 = diff.cross(e1);
+  barycentricCoord.z = denom * diffXe1.dot(r.direction());
+  
+  // check if barycenter.z inside triangle
+  if(barycentricCoord.z < -EPSILON || barycentricCoord.z > 1.0f+EPSILON) return false;
+
+  // compute barycenter.x and check if inside
+  barycentricCoord.x = 1.0f - barycentricCoord.y - barycentricCoord.z;
+  if(barycentricCoord.y + barycentricCoord.z > 1.0f+EPSILON) return false;
+
+  // compute t
+  t = denom * diffXe1.dot(e2);
+
+  // check if in front (i.e., t>0)
+  if(t < EPSILON) return false;
+
+  // Clamp (to compensate for roundoff errors)
+  barycentricCoord.clamp(0.0f, 1.0f);
+
+  // Done.
+  return true;
+}
+
+
+boundingBox triangle::boundingbox(void) const
+{
+  boundingBox bb;
+  for(unsigned int i=0; i < 3; i++)
+    bb += vertex(i);
+  return bb;
+}
+
+
+vec3d triangle::vertex(const vec3d& barycentricCoord) const
+{
+  vec3d result(0.0f);
+  for(unsigned int i=0; i < 3; i++)
+    result += vertex(i) * barycentricCoord[i];
+  return result;
+}
+
+
+vec3d triangle::normal(void) const
+{
+  vec3d e1 = vertex(1) - vertex(0);
+  vec3d e2 = vertex(2) - vertex(0);
+  return e1.cross(e2).normalize();
+}
+
+vec3d triangle::shadingAxis(void) const
+{
+  // follow texture coordinates if defined, otherwise, return the first axis.
+  if(!_textureCoord_list) return normalize(vertex(1)-vertex(0));
+
+  // find the vector that follows the U-axis of the texture coordinates
+  // solve:
+  // [ (t1-t0) (t2-t0) ] [ delta_beta delta_gamma ]^T = [1 0]^T
+  // for delta_beta and delta_gamma.
+  vec3d v1 = vertex(1) - vertex(0);
+  vec3d v2 = vertex(2) - vertex(0);
+  vec2d t1 = textureCoordinate(1) - textureCoordinate(0);
+  vec2d t2 = textureCoordinate(2) - textureCoordinate(0);
+
+  // check special cases where U or V is aligned with a vertex
+  if( fabs(t1.v) < EPSILON ) return normalize(t1.u*v1);
+  if( fabs(t2.v) < EPSILON ) return normalize(t2.u*v2);
+
+  // compute delta_beta
+  float inv_delta_beta = t1.u - t1.v*t2.u/t2.v;
+
+  // => degenrate case
+  if(fabs(inv_delta_beta) < EPSILON) return normalize(v1);
+
+  float delta_beta = 1.0f / inv_delta_beta;
+  float delta_gamma = -delta_beta * t1.v / t2.v;
+
+  // compute U
+  return normalize( delta_beta*v1 + delta_gamma*v2 );
+}
+
+
+vec3d triangle::normal(const vec3d& barycentricCoord) const
+{
+  // sanity check
+  if(!hasPerVertexNormals()) return normal();
+  
+  // interpolate
+  vec3d result(0.0f);
+  for(unsigned int i=0; i < 3; i++)
+    result += normal(i) * barycentricCoord[i];
+  return result.normalize();
+}
+
+
+vec2d triangle::textureCoordinate(const vec3d& barycentricCoord) const
+{
+  // sanity check
+  if(!hasPerVertexTextureCoordinates()) return vec2d();
+
+  // interpolate
+  vec2d result(0.0f);
+  for(unsigned int i=0; i < 3; i++)
+    result += textureCoordinate(i) * barycentricCoord[i];
+  return result;
+}
+
+
+float triangle::area(void) const
+{
+  vec3d e1 = vertex(1) - vertex(0);
+  vec3d e2 = vertex(2) - vertex(0);
+  return 0.5f * e1.cross(e2).length();
+}
+
+
+vec3d triangle::sample(float r1, float r2, vec3d& barycentricCoord, float& pdf) const
+{
+  r2 = sqrt(r2);
+
+  // compute barycentric coordinate
+  barycentricCoord.x = r1*r2;
+  barycentricCoord.y = (1.0f - r2);
+  barycentricCoord.z = 1.0f - barycentricCoord.x - barycentricCoord.y;
+  
+  // compute pdf
+  pdf = 1.0f / area();
+
+  // Done.
+  return vertex(barycentricCoord);
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void triangle::_assign(const triangle& t)
+{
+  // avoid self-assign
+  if(&t == this) return;
+
+  // share ptr to list
+  _vertex_list = t._vertex_list;
+  _normal_list = t._normal_list;
+  _textureCoord_list = t._textureCoord_list;
+
+  // copy indices
+  _vertex_idx = t._vertex_idx;
+  _normal_idx = t._normal_idx;
+  _textureCoord_idx = t._textureCoord_idx;
+}
+
+
+void triangle::_swap(triangle& t)
+{
+  // copy list ptr
+  std::swap(_vertex_list, t._vertex_list);
+  std::swap(_normal_list, t._normal_list);
+  std::swap(_textureCoord_list, t._textureCoord_list);
+
+  // copy indices
+  std::swap(_vertex_idx, t._vertex_idx);
+  std::swap(_normal_idx, t._normal_idx);
+  std::swap(_textureCoord_idx, t._textureCoord_idx);
+}
+
diff --git a/hw6/src/triangleMesh.cpp b/hw6/src/triangleMesh.cpp
new file mode 100644
index 0000000..5507a9c
--- /dev/null
+++ b/hw6/src/triangleMesh.cpp
@@ -0,0 +1,57 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include <algorithm>
+#include "triangleMesh.h"
+
+/////////////////
+// Constructors //
+//////////////////
+triangleMesh::triangleMesh(void)
+  : boundedCompound()
+{
+  // Nothing.
+}
+
+
+triangleMesh::triangleMesh(const std::vector<triangle>& triangle_list, const std::shared_ptr<const shader_base>& shader, const transformation3d& transform)
+  : boundedCompound(transform, shader)
+{
+  // allocate sufficient memory
+  _triangles.reserve(triangle_list.size());
+
+  // construct vector of boundedTriangles 
+  for_each(triangle_list.begin(), triangle_list.end(), [&](const triangle& tri)
+  {
+    _triangles.push_back( std::make_shared<boundedTriangle>(tri, shader) );
+  });
+
+  // Done.
+  initializeBoundingBox();
+}
+
+
+/////////////
+// Methods //
+/////////////
+const std::vector<std::shared_ptr<const boundedPrimitive>>& triangleMesh::compounds(void) const
+{
+  return _triangles;
+}
+
+
+bool triangleMesh::hasShader(void) const
+{
+  return boundedPrimitive::hasShader();
+}
+
+
+void triangleMesh::_print(std::ostream& s) const
+{
+  s << "triangleMesh (" << _bb << ", " << _triangles.size() << " compounds)";
+}
diff --git a/hw6/src/util.cpp b/hw6/src/util.cpp
new file mode 100644
index 0000000..917eef4
--- /dev/null
+++ b/hw6/src/util.cpp
@@ -0,0 +1,45 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+#include "util.h"
+
+
+std::string getFilename(const std::string& path)
+{
+#ifdef _WIN32
+  unsigned char pathSep = '\\';
+#else
+  unsigned char pathSep = '/';
+#endif
+  size_t start = path.find_last_of(pathSep);
+  size_t end = path.find_last_of(".");
+  if(start == std::string::npos) start = -1;
+  if(end == std::string::npos) end = path.size();
+  return path.substr(start+1, end-start-1);
+}
+
+
+std::string getExtension(const std::string& path)
+{
+  size_t lastidx = path.find_last_of("."); 
+  if(lastidx == std::string::npos) return std::string();
+  else return path.substr(lastidx+1, std::string::npos);
+}
+
+
+std::string getDirectory(const std::string& path)
+{
+#ifdef _WIN32
+  unsigned char pathSep = '\\';
+#else
+  unsigned char pathSep = '/';
+#endif
+  size_t lastidx = path.find_last_of(pathSep);
+  if(lastidx == std::string::npos) return std::string();
+  return path.substr(0, lastidx+1);
+}
diff --git a/hw6/src/vec2d.cpp b/hw6/src/vec2d.cpp
new file mode 100644
index 0000000..ae12e41
--- /dev/null
+++ b/hw6/src/vec2d.cpp
@@ -0,0 +1,258 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include <cassert>
+#include <algorithm>
+#include "vec2d.h"
+
+//////////////////
+// Constructors //
+//////////////////
+vec2d::vec2d(vec2d::const_reference value)
+{ 
+  x = y = value;
+}
+
+
+vec2d::vec2d(vec2d::const_reference x, vec2d::const_reference y) 
+{
+  this->x = x;
+  this->y = y;
+}
+
+
+vec2d::vec2d(const vec2d& v)
+{
+  x = v.x;
+  y = v.y;
+}
+ 
+
+////////////////
+// Inspectors //
+////////////////
+vec2d::const_reference vec2d::operator[](size_t index) const 
+{ 
+  assert(index < size());
+  return data[index]; 
+}
+
+
+vec2d::reference vec2d::operator[](size_t index) 
+{ 
+  assert(index < size());
+  return data[index]; 
+}
+
+
+vec2d::iterator vec2d::begin(void)
+{
+  return data;
+}
+
+
+vec2d::const_iterator vec2d::begin(void) const
+{
+  return data;
+}
+
+
+vec2d::iterator vec2d::end(void)
+{
+  return begin() + size();
+}
+
+
+vec2d::const_iterator vec2d::end(void) const
+{
+  return begin() + size();
+}
+
+
+///////////////
+// Operators //
+///////////////
+vec2d& vec2d::operator=(const vec2d& v) 
+{ 
+  _assign(v); 
+  return *this; 
+}
+
+
+bool vec2d::operator==(const vec2d& v) const 
+{ 
+  return (x == v.x) && (y == v.y); 
+}
+
+
+bool vec2d::operator!=(const vec2d& v) const 
+{ 
+  return (x != v.x) || (y != v.y); 
+}
+  
+
+vec2d vec2d::operator-(void) const
+{
+  return vec2d(-x, -y);
+}
+
+
+vec2d vec2d::operator+(const vec2d& v) const 
+{ 
+  return vec2d(x + v.x, y + v.y); 
+}
+
+
+vec2d vec2d::operator-(const vec2d& v) const 
+{ 
+  return vec2d(x - v.x, y - v.y); 
+}
+
+
+vec2d vec2d::operator*(const vec2d& v) const 
+{ 
+  return vec2d(x * v.x, y * v.y); 
+}
+
+
+vec2d vec2d::operator*(vec2d::const_reference scale) const 
+{ 
+  return vec2d(x * scale, y * scale); 
+}
+
+
+vec2d vec2d::operator/(const vec2d& v) const 
+{ 
+  return vec2d(x / v.x, y / v.y); 
+}
+
+
+vec2d vec2d::operator/(vec2d::const_reference scale) const 
+{ 
+  return vec2d(x / scale, y / scale); 
+}
+
+
+vec2d& vec2d::operator+=(const vec2d& v) 
+{ 
+  x += v.x; 
+  y += v.y; 
+  return *this; 
+}
+
+
+vec2d& vec2d::operator-=(const vec2d& v) 
+{ 
+  x -= v.x;
+  y -= v.y;
+  return *this; 
+}
+
+
+vec2d& vec2d::operator*=(const vec2d& v) 
+{ 
+  x *= v.x;
+  y *= v.y;
+  return *this; 
+}
+
+
+vec2d& vec2d::operator*=(vec2d::const_reference scale) 
+{ 
+  x *= scale;
+  y *= scale;
+  return *this; 
+}
+
+
+vec2d& vec2d::operator/=(const vec2d& v) 
+{ 
+  x /= v.x;
+  y /= v.y;
+  return *this; 
+}							
+
+
+vec2d& vec2d::operator/=(vec2d::const_reference scale) 
+{ 
+  x /= scale;
+  y /= scale;
+  return *this; 
+}
+
+
+
+///////////////
+// Modifiers //
+///////////////
+vec2d::value_type vec2d::dot(const vec2d& v) const 
+{ 
+  return (x*v.x + y*v.y);
+}
+
+
+vec2d::value_type vec2d::squared_length(void) const 
+{ 
+  return dot(*this); 
+}
+
+
+vec2d::value_type vec2d::length(void) const 
+{ 
+  return sqrt(squared_length()); 
+}
+
+
+vec2d::value_type vec2d::squared_distance(const vec2d& v) const 
+{
+  return (*this - v).squared_length(); 
+}
+
+
+vec2d::value_type vec2d::distance(const vec2d& v) const 
+{ 
+  return sqrt(squared_distance(v)); 
+}
+
+
+///////////////
+// Modifiers //
+///////////////
+vec2d& vec2d::abs(void)
+{
+  std::for_each(begin(), end(), [](reference val) 
+  { 
+    if(val < 0) val = -val; 
+  });
+  return *this;
+}
+
+
+vec2d& vec2d::normalize(void)
+{ 
+  *this /= length();
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void vec2d::_assign(const vec2d& v)
+{ 
+  x = v.x;  
+  y = v.y; 
+}
+
+
+void vec2d::_swap(vec2d& v) 
+{
+  std::swap(x, v.x);
+  std::swap(y, v.y);
+}
diff --git a/hw6/src/vec3d.cpp b/hw6/src/vec3d.cpp
new file mode 100644
index 0000000..3b20ad5
--- /dev/null
+++ b/hw6/src/vec3d.cpp
@@ -0,0 +1,287 @@
+/******************************************************************/
+/* This file is part of the homework assignments for CSCI-427/527 */
+/* at The College of William & Mary and authored by Pieter Peers. */
+/* No part of this file, whether altered or in original form, can */
+/* be distributed or used outside the context of CSCI-427/527     */
+/* without consent of either the College of William & Mary or     */
+/* Pieter Peers.                                                  */
+/******************************************************************/
+
+#include <cassert>
+#include <algorithm>
+#include "vec3d.h"
+
+//////////////////
+// Constructors //
+//////////////////
+vec3d::vec3d(vec3d::const_reference value)
+{ 
+  x = y = z = value;
+}
+
+
+vec3d::vec3d(vec3d::const_reference x, vec3d::const_reference y, vec3d::const_reference z) 
+{
+  this->x = x;
+  this->y = y;
+  this->z = z;
+}
+
+
+vec3d::vec3d(const vec3d& v)
+{
+  x = v.x;
+  y = v.y;
+  z = v.z;
+}
+ 
+
+////////////////
+// Inspectors //
+////////////////
+vec3d::const_reference vec3d::operator[](size_t index) const 
+{ 
+  assert(index < size());
+  return data[index]; 
+}
+
+
+vec3d::reference vec3d::operator[](size_t index) 
+{ 
+  assert(index < size());
+  return data[index]; 
+}
+
+
+vec3d::iterator vec3d::begin(void)
+{
+  return data;
+}
+
+
+vec3d::const_iterator vec3d::begin(void) const
+{
+  return data;
+}
+
+
+vec3d::iterator vec3d::end(void)
+{
+  return begin() + size();
+}
+
+
+vec3d::const_iterator vec3d::end(void) const
+{
+  return begin() + size();
+}
+
+
+///////////////
+// Operators //
+///////////////
+vec3d& vec3d::operator=(const vec3d& v) 
+{ 
+  _assign(v); 
+  return *this; 
+}
+
+
+bool vec3d::operator==(const vec3d& v) const 
+{ 
+  return (x == v.x) && (y == v.y) && (z == v.z); 
+}
+
+
+bool vec3d::operator!=(const vec3d& v) const 
+{ 
+  return (x != v.x) || (y != v.y) || (z != v.z); 
+}
+  
+
+vec3d vec3d::operator-(void) const
+{
+  return vec3d(-x, -y, -z);
+}
+
+
+vec3d vec3d::operator+(const vec3d& v) const 
+{ 
+  return vec3d(x + v.x, y + v.y, z + v.z); 
+}
+
+
+vec3d vec3d::operator-(const vec3d& v) const 
+{ 
+  return vec3d(x - v.x, y - v.y, z - v.z); 
+}
+
+
+vec3d vec3d::operator*(const vec3d& v) const 
+{ 
+  return vec3d(x * v.x, y * v.y, z * v.z); 
+}
+
+
+vec3d vec3d::operator*(vec3d::const_reference scale) const 
+{ 
+  return vec3d(x * scale, y * scale, z * scale); 
+}
+
+
+vec3d vec3d::operator/(const vec3d& v) const 
+{ 
+  return vec3d(x / v.x, y / v.y, z / v.z); 
+}
+
+
+vec3d vec3d::operator/(vec3d::const_reference scale) const 
+{ 
+  return vec3d(x / scale, y / scale, z / scale); 
+}
+
+
+vec3d& vec3d::operator+=(const vec3d& v) 
+{ 
+  x += v.x; 
+  y += v.y; 
+  z += v.z; 
+  return *this; 
+}
+
+
+vec3d& vec3d::operator-=(const vec3d& v) 
+{ 
+  x -= v.x;
+  y -= v.y;
+  z -= v.z;
+  return *this; 
+}
+
+
+vec3d& vec3d::operator*=(const vec3d& v) 
+{ 
+  x *= v.x;
+  y *= v.y;
+  z *= v.z;
+  return *this; 
+}
+
+
+vec3d& vec3d::operator*=(vec3d::const_reference scale) 
+{ 
+  x *= scale;
+  y *= scale;
+  z *= scale;
+  return *this; 
+}
+
+
+vec3d& vec3d::operator/=(const vec3d& v) 
+{ 
+  x /= v.x;
+  y /= v.y;
+  z /= v.z;
+  return *this; 
+}							
+
+
+vec3d& vec3d::operator/=(vec3d::const_reference scale) 
+{ 
+  x /= scale;
+  y /= scale;
+  z /= scale;
+  return *this; 
+}
+
+
+
+///////////////
+// Modifiers //
+///////////////
+vec3d::value_type vec3d::dot(const vec3d& v) const 
+{ 
+  return (x*v.x + y*v.y + z*v.z);
+}
+
+
+vec3d::value_type vec3d::squared_length(void) const 
+{ 
+  return dot(*this); 
+}
+
+
+vec3d::value_type vec3d::length(void) const 
+{ 
+  return sqrt(squared_length()); 
+}
+
+
+vec3d::value_type vec3d::squared_distance(const vec3d& v) const 
+{
+  return (*this - v).squared_length(); 
+}
+
+
+vec3d::value_type vec3d::distance(const vec3d& v) const 
+{ 
+  return sqrt(squared_distance(v)); 
+}
+
+
+vec3d vec3d::cross(const vec3d& v) const
+{
+  return vec3d(y*v.z - z*v.y,
+	       z*v.x - x*v.z,
+	       x*v.y - y*v.x); 
+}
+
+
+///////////////
+// Modifiers //
+///////////////
+vec3d& vec3d::abs(void)
+{
+  std::for_each(begin(), end(), [](reference val) 
+  { 
+    if(val < 0) val = -val; 
+  });
+  return *this;
+}
+
+
+vec3d& vec3d::clamp(vec3d::value_type lower, vec3d::value_type upper)
+{
+  std::for_each(begin(), end(), [&](reference val) 
+  { 
+    if(val < lower) val = lower; 
+    else if(val > upper) val = upper;
+  });
+  return *this;
+}
+
+
+vec3d& vec3d::normalize(void)
+{ 
+  *this /= length();
+  return *this;
+}
+
+
+/////////////////////
+// Private Methods //
+/////////////////////
+void vec3d::_assign(const vec3d& v)
+{ 
+  x = v.x;  
+  y = v.y; 
+  z = v.z; 
+}
+
+
+void vec3d::_swap(vec3d& v) 
+{
+  std::swap(x, v.x);
+  std::swap(y, v.y);
+  std::swap(z, v.z);
+}