glm::vec3 DirectLightingIntegrator::LightPDFEnergy(const Intersection &light_sample_isx, const Intersection &isx, const Ray &light_sample, const glm::vec3 &woW, unsigned int n_light, unsigned int n_brdf)
{
glm::vec3 ray_color(0, 0, 0);
Material* M = isx.object_hit->material; //material of point hit
Geometry* L = light_sample_isx.object_hit; //light source
float lightPDF = L->RayPDF(light_sample_isx, light_sample);
//if light pdf is less than zero, return no light
if (lightPDF <= 0.0f)
{
return glm::vec3(0);
}
//get BRDFPDF and energy from the material
float brdfPDF;
float dummy;
glm::vec3 M_energy(M->EvaluateScatteredEnergy(isx, woW, light_sample.direction, brdfPDF));
//terminate early if brdf pdf is zero;
if (brdfPDF <= 0.0f) return ray_color;
glm::vec3 L_energy(L->material->EvaluateScatteredEnergy(light_sample_isx, woW, -light_sample.direction, dummy));
float W = MIS(lightPDF, brdfPDF); //MIS power heuristic weighing function
ray_color = ComponentMult(L_energy, M_energy); // multiply the energy of the light with BRDF reflected energy
ray_color = ComponentMult(ComponentMult(ray_color, M->base_color), isx.texture_color);
ray_color = ray_color*W/lightPDF*glm::abs(glm::dot(isx.normal, light_sample.direction)); // and then do the solid angle PDF and the cosine
return ray_color;
}
glm::vec3 Integrator::CalculateEnergy(const Intersection &light_sample_isx, const Intersection &isx, const Ray &light_sample, const glm::vec3 &woW)
{
glm::vec3 ray_color(0, 0, 0);
Material* M = isx.object_hit->material; //material of point hit
Geometry* L = light_sample_isx.object_hit; //light source
float dummy;
//Intersection isx_light = L->GetIntersection(light_sample);
ray_color = ComponentMult(L->material->EvaluateScatteredEnergy(light_sample_isx, woW, -light_sample.direction, dummy), M->EvaluateScatteredEnergy(isx, woW, light_sample.direction, dummy)); // multiply the energy of the light with BRDF reflected energy
ray_color = ray_color/L->RayPDF(light_sample_isx, light_sample)*glm::abs(glm::dot(isx.normal, light_sample.direction)); // and then do the solid angle PDF and the cosine
ray_color = glm::clamp(ray_color, 0.0f, 1.0f);
return ray_color;
}
glm::vec3 DirectLightingIntegrator::BxDFPDFEnergy(const Intersection &isx, const glm::vec3 &woW, unsigned int n_light, unsigned int n_brdf)
{
glm::vec3 ray_color(0, 0, 0);
glm::vec3 wiW(0, 0, 0);//this will be obtained by sampling BxDf
Material* M = isx.object_hit->material; //material of point hit
float brdfPDF;
float lightPDF;
float dummy;
float rand1 = unif_distribution(mersenne_generator);
float rand2 = unif_distribution(mersenne_generator);
glm::vec3 M_energy(M->SampleAndEvaluateScatteredEnergy(isx, woW, wiW, brdfPDF, rand1, rand2));
//use sampled wiW to check if I can hit the light
Ray shadow_feeler(isx.point, wiW);
Intersection light_isx = intersection_engine->GetIntersection(shadow_feeler);
Geometry* L; //this holds the intersected light source
//terminate early if brdf pdf is zero;
if (brdfPDF <= 0.0f) return ray_color;
if (light_isx.object_hit == NULL)//if ray didnt hit anything
return ray_color;
if (light_isx.object_hit->material->is_light_source)
{
L = light_isx.object_hit;
lightPDF = L->RayPDF(light_isx, shadow_feeler);
if (lightPDF <= 0)
{
return ray_color;
}
glm::vec3 L_energy(L->material->EvaluateScatteredEnergy(light_isx, woW, -shadow_feeler.direction, dummy));
float W = MIS(brdfPDF, lightPDF);
ray_color = ComponentMult(L_energy, M_energy);
ray_color = ComponentMult(ComponentMult(ray_color, M->base_color), isx.texture_color);
ray_color = ray_color*W/brdfPDF*glm::abs(glm::dot(isx.normal, shadow_feeler.direction));
return ray_color;
}
else
{
return ray_color;
}
}