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 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;
}
}
int main() {
#ifndef ONLINE_JUDGE
freopen("c.in", "rt", stdin);
//freopen("c.txt", "wt", stdout);
#endif
int n = 200;
while(true)
{
for (int i = 0; i < n; i++)
{
W[i + 1] = rand();
if(rand()%2)
W[i+1] *= -1;
}
assert(MIS(n) == BB_Tight(n));
}
return 0;
}
glm::vec3 AllLightingIntegrator::LightIndirectEnergy(const Intersection &isx, unsigned int n_split, const glm::vec3 &woW)
{
int depth = 0;
Intersection isx_temp = isx;//reflected intersection
Intersection isx_light; //sampled intersection with "light source"
glm::vec3 color_accum(0.0f, 0.0f, 0.0f); //accumulated color
glm::vec3 color_temp(0.0f, 0.0f, 0.0f);
glm::vec3 wi_temp(0.0f, 0.0f, 0.0f);
glm::vec3 wo_temp(woW);
glm::vec3 brdf_energy_accum(1.0f, 1.0f, 1.0f);
glm::vec3 brdf_energy_temp(0.0f, 0.0f, 0.0f);
glm::vec3 L_temp(0.0f, 0.0f, 0.0f);
Material* M_temp = isx.object_hit->material;
Geometry* obj_temp; //stores the temporary sampled object
Ray sampler;
float pdf_temp_brdf(0);
float pdf_light_temp(0);
float W(0); //for MIS
float rand1 = unif_distribution(mersenne_generator);
float rand2 = unif_distribution(mersenne_generator);
float epsilon = 0.0001f;
float throughput = 1.000001f;
float russian = unif_distribution(mersenne_generator);
//default samples for direct lighting when estimating the irradiance of some other point in the scene
unsigned int n_light = 10;
unsigned int n_brdf = 10;
int light_source_choice(0);
while(depth < max_depth && (russian < throughput || depth < 2))
{
//sample a random point on a random object in the scene
light_source_choice = rand()%scene->objects.count();
obj_temp = scene->objects[light_source_choice];
//if I hit a real light source, kill the ray
if (scene->objects[light_source_choice]->material->is_light_source) break;
isx_light = obj_temp->GetRandISX(rand1, rand2, isx_temp.normal);
//update random numbers
rand1 = unif_distribution(mersenne_generator);
rand2 = unif_distribution(mersenne_generator);
//make ray towards these points
wi_temp = glm::normalize(isx_light.point - isx_temp.point);
sampler = Ray(isx_temp.point, wi_temp);
//update my light intersection
isx_light = intersection_engine->GetIntersection(sampler);
//this ray dies if it hit nothing or is blocked, kill the ray as well
if(isx_light.object_hit == NULL) break;
if(isx_light.object_hit != obj_temp) break;
//to avoid shadow acne
isx_light.point = isx_light.point + epsilon*isx_light.normal;
//find out the pdf w/r/t light
pdf_light_temp = obj_temp->RayPDF(isx_light, sampler);
//if my pdf is negative, kill the ray as well
if(pdf_light_temp <= 0) break;
//update accumulated brdf energy
brdf_energy_temp = M_temp->EvaluateScatteredEnergy(isx_temp, wo_temp, wi_temp, pdf_temp_brdf);
brdf_energy_accum = ComponentMult(brdf_energy_accum, brdf_energy_temp);
//find the direct lighting irradiance of this point towards my original intersection
wo_temp = -wi_temp; //now the old incoming ray is the outgoing ray for the new intersection
L_temp = EstimateDirectLighting(isx_light, n_light, n_brdf, wo_temp);
W = MIS(pdf_light_temp, pdf_temp_brdf);
//this is light source sampling so use the illumination equation for BRDF sampling to accumulate color
color_temp = ComponentMult(brdf_energy_accum, L_temp);
color_temp = ComponentMult(ComponentMult(color_temp, M_temp->base_color), isx_temp.texture_color);
color_temp = color_temp*W/pdf_light_temp*glm::abs(glm::dot(isx_temp.normal, wi_temp));
color_accum = color_accum + color_temp/static_cast<float>(n_split);
throughput = throughput * glm::max(glm::max(color_accum.r, color_accum.g), color_accum.b);
//update the temporary material
M_temp = isx_light.object_hit->material;
isx_temp = isx_light;
//update random number
//update depth
depth++;
russian = unif_distribution(mersenne_generator);
}
return color_accum;
}
glm::vec3 AllLightingIntegrator::BxDFIndirectEnergy(const Intersection &isx, unsigned int n_split, const glm::vec3 &woW)
{
int depth = 0;
Intersection isx_temp = isx;//reflected intersection
Intersection isx_light; //sampled intersection with "light source"
glm::vec3 color_accum(0.0f, 0.0f, 0.0f); //accumulated color
glm::vec3 color_temp(0.0f, 0.0f, 0.0f);
glm::vec3 wi_temp(0.0f, 0.0f, 0.0f);
glm::vec3 wo_temp(woW);
glm::vec3 brdf_energy_accum(1.0f, 1.0f, 1.0f);
glm::vec3 brdf_energy_temp(0.0f, 0.0f, 0.0f);
glm::vec3 L_temp(0.0f, 0.0f, 0.0f);
Material* M_temp = isx.object_hit->material;
Ray sampler;
float pdf_temp_brdf(0);
float pdf_light_temp(0);
float W(0); //for MIS
float rand1 = unif_distribution(mersenne_generator);
float rand2 = unif_distribution(mersenne_generator);
float epsilon = 0.0001;
float throughput = 1.000001f;
float russian = unif_distribution(mersenne_generator);
//default samples for direct lighting when estimating the irradiance of some other point in the scene
unsigned int n_light = 10;
unsigned int n_brdf = 10;
while(depth < max_depth && (russian < throughput || depth < 2))
{
//sample random brdf starting at the input isx direction to get reflected ray to begin
brdf_energy_temp = M_temp->SampleAndEvaluateScatteredEnergy(isx_temp, wo_temp, wi_temp, pdf_temp_brdf, rand1, rand2);
//update accumulated brdf energy
brdf_energy_accum = ComponentMult(brdf_energy_accum, brdf_energy_temp);
//use the sampled incoming ray to find a reflected intersection
sampler = Ray(isx_temp.point, wi_temp);
isx_light = intersection_engine->GetIntersection(sampler);
//this ray dies if I hit a real light source or nothing
if(isx_light.object_hit == NULL) break;
else if(isx_light.object_hit->material->is_light_source) break;
//
//to avoid shadow acne
isx_light.point = isx_light.point + epsilon*isx_light.normal;
//find the direct lighting irradiance of this point towards my original intersection
wo_temp = -wi_temp; //now the old incoming ray is the outgoing ray for the new intersection
L_temp = EstimateDirectLighting(isx_light, n_light, n_brdf, wo_temp); //the direct lighting towards the isx
pdf_light_temp = isx_light.object_hit->RayPDF(isx_light, sampler);
W = MIS(pdf_temp_brdf, pdf_light_temp);
//this is BRDF sampling so use the illumination equation for BRDF sampling to accumulate color
color_temp = ComponentMult(brdf_energy_accum, L_temp);
color_temp = ComponentMult(ComponentMult(color_temp, M_temp->base_color), isx_temp.texture_color);
color_temp = color_temp*W/pdf_temp_brdf*glm::abs(glm::dot(isx_temp.normal, wi_temp));
color_accum = color_accum + color_temp/static_cast<float>(n_split);
throughput = throughput * glm::max(glm::max(color_accum.r, color_accum.g), color_accum.b);
//update the temporary material
M_temp = isx_light.object_hit->material;
isx_temp = isx_light;
//update random number
rand1 = unif_distribution(mersenne_generator);
rand2 = unif_distribution(mersenne_generator);
//update depth
depth++;
russian = unif_distribution(mersenne_generator);
}
return color_accum;
}
