glm::vec3 BlinnMicrofacetBxDF::EvaluateHemisphereScatteredEnergy(const glm::vec3 &wo, int num_samples, const glm::vec2 *samples) const
{
//TODO
glm::vec3 color( 0.f );
for( int i = 0; i < num_samples; ++i ){
float cos_theta( powf( samples[ i ].x, 1.f / ( exponent + 1.f ) ) );
float sin_theta( sqrtf( fmaxf( 0.f, 1.f - cos_theta * cos_theta ) ) );
float phi( samples[ i ].y * TWO_PI );
float cos_phi( cosf( phi ) );
float sin_phi( sinf( phi ) );
glm::vec3 wh( sin_theta * cos_phi, sin_theta * sin_phi, cos_theta );
float woDwh( glm::dot( wo, wh ) );
if( woDwh < 0.f ) wh = -wh;
glm::vec3 wi( -wo + 2.f * woDwh * wh );
color += EvaluateScatteredEnergy( wo, wi );
}
return color / ( float )num_samples;
}
glm::vec3 SpecularReflectionBxDF::SampleAndEvaluateScatteredEnergy(const glm::vec3 &wo, glm::vec3 &wi_ret, float rand1, float rand2, float &pdf_ret) const
{
// specular reflection wi = delta(w-wo) where w is perfectly reflective direction
glm::vec3 N(0,0,1);
wi_ret = 2.0f*glm::dot(N,wo)*N - wo;
wi_ret = glm::normalize(wi_ret);
//pdf_ret = PDF(wo, wi_ret);
return EvaluateScatteredEnergy(wo, wi_ret, pdf_ret);
}
glm::vec3 BxDF::SampleAndEvaluateScatteredEnergy(const glm::vec3 &wo, glm::vec3 &wi_ret, float rand1, float rand2, float &pdf_ret) const
{
glm::vec3 tmp = la::UnifSampleDisc(rand1, rand2);
tmp.z = sqrtf(std::max(0.f, 1.f - tmp.x*tmp.x - tmp.y*tmp.y));
if (wo.z < 0.f) tmp.z *= -1.f;
wi_ret = tmp;
pdf_ret = PDF(wo, wi_ret);
return EvaluateScatteredEnergy(wo, wi_ret);
}
glm::vec3 LambertBxDF::SampleAndEvaluateScatteredEnergy(const glm::vec3 &wo, glm::vec3 &wi_ret, float rand1, float rand2, float &pdf_ret) const
{
glm::vec3 normal=glm::vec3(0,0,1);
float t = 2*PI*rand1;
float u = rand2-0.5;//[-0.5,+0.5]*/
float x=u*cos(t);
float y=u*sin(t);
float z=sqrt(0.25-pow(x,2.0)-pow(y,2.0));
wi_ret=glm::normalize(glm::vec3(x,y,z));
pdf_ret=glm::dot(wi_ret,normal)/PI;
return EvaluateScatteredEnergy(wo, wi_ret);
}
glm::vec3 BxDF::SampleAndEvaluateScatteredEnergy(const glm::vec3 &wo, glm::vec3 &wi_ret, float rand1, float rand2, float &pdf_ret) const
{
//TODO
rand1 *= TWO_PI;
rand2 *= PI * .5f;
float x( cosf( rand1 ) * sinf( rand2 ) );
float y( sinf( rand1 ) * sinf( rand2 ) );
float z( cosf( rand2 ) );
wi_ret = glm::vec3( x, y, z );
pdf_ret = PDF( wo, wi_ret );
return EvaluateScatteredEnergy( wo, wi_ret );
}
glm::vec3 BlinnMicrofacetBxDF::SampleAndEvaluateScatteredEnergy(const glm::vec3 &wo, glm::vec3 &wi_ret, float rand1, float rand2, float &pdf_ret) const{
float cos_theta( powf( rand1, 1.f / ( exponent + 1.f ) ) );
float sin_theta( sqrtf( fmaxf( 0.f, 1.f - cos_theta * cos_theta ) ) );
float phi( rand2 * TWO_PI );
float cos_phi( cosf( phi ) );
float sin_phi( sinf( phi ) );
glm::vec3 wh( sin_theta * cos_phi, sin_theta * sin_phi, cos_theta );
float woDwh( glm::dot( wo, wh ) );
if( woDwh < 0.f ) wh = -wh;
wi_ret = -wo + 2.f * woDwh * wh;
pdf_ret = PDF( wo, wi_ret );
return EvaluateScatteredEnergy( wo, wi_ret );
}
glm::vec3 BxDF::EvaluateHemisphereScatteredEnergy(const glm::vec3 &wo, int num_samples, const glm::vec2* samples) const
{
//TODO
glm::vec3 color( 0.f );
for( int i = 0; i < num_samples; ++i ){
float r( sqrtf( samples[ i ].x ) );
float theta( samples[ i ].y * TWO_PI );
float x( r * cosf( theta ) );
float y( r * sinf( theta ) );
float z( sqrtf( 1.f - samples[ i ].x ) );
glm::vec3 wi( x, y, z );
color += EvaluateScatteredEnergy( wo, wi );
}
return color / ( float )num_samples;
}
