/******************************************************************/
/* 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;  
}