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