/******************************************************************/
/* 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
{
  // HW5: Implement this. Given a 'direction' return the corresponding
  //      texel from the _map. The environment map uses spherical coordinates
  //      for mapping a direction to a (phi, theta) pair (which are subsequently
  //      mapped to pixel coordinates. (x,y,z) = (cos(phi)*sin(theta),
  //      sin(phi)*sin(theta), cos(theta)).
  // Modifies: nothing
  // Returns: color
  vec3d reflect_dir = _transform.inverseTransformDirection(direction); // invert
  float phi = (acos(reflect_dir.z) + PI) / PI; // make positive, scale: 180
  float theta = atan2(reflect_dir.y, reflect_dir.x) / (2 * PI); // scale: 360
  return (*_map)(vec2d(theta, phi)); // return texel
}


///////////////////////
// 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 << ")";
}