/******************************************************************/
/* 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();
}