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