Color3 PathIntegrator::li(const Scene *scene_ptr, const Ray &ray, const hitRecord &record, const Sample* sample_ptr,
Random462 &rng) {
Color3 L = Color3::Black();
if (record.shape_ptr == NULL)
return L;
for (uint32_t j = 0; j < num_per_path; j++) {
bool specular_bounce = false;
const hitRecord *current_h_ptr = &record;
hitRecord path_record;
Ray current_ray(ray);
Color3 path_weight = Color3::White();
LightSampleSet light_set;
BSDFSampleSet bsdf_set;
BSDFSample path_sample;
float select;
light_set.num = 1;
bsdf_set.num = 1;
Color3 new_path_l;
Color3 bsdf_factor;
Color3 weight_records[7];
for (uint32_t i = 0; i < max_depth; i++) {
Vector3 p = current_h_ptr->p;
Vector3 n = current_h_ptr->n;
Vector3 wo = -current_ray.d;
BSDF *bsdf_ptr = current_h_ptr->bsdf_ptr;
if (i == 0 || specular_bounce) {
if (current_h_ptr->shape_ptr->light_ptr != NULL) {
L += path_weight *
current_h_ptr->shape_ptr->light_ptr->L(n, wo);
}
}
// TODO: hit light source?
if (current_h_ptr->shape_ptr->light_ptr != NULL)
break;
if (i < sample_depth) {
light_set.light_1d = (float*) sample_ptr + 2 + light_offsets[j * sample_depth + i].offset_1d;
light_set.light_2d = (float*) sample_ptr + 2 + light_offsets[j * sample_depth + i].offset_2d;
bsdf_set.bsdf_1d = (float*) sample_ptr + 2 + bsdf_offsets[j * sample_depth + i].offset_1d;
bsdf_set.bsdf_2d = (float*) sample_ptr + 2 + bsdf_offsets[j * sample_depth + i].offset_2d;
float* path_sample_ptr = (float*) sample_ptr + 2 + path_offsets[j * sample_depth + i].offset_2d;
path_sample.r1 = path_sample_ptr[0];
path_sample.r2 = path_sample_ptr[1];
path_sample.c = *((float*) sample_ptr + 2 + path_offsets[j * sample_depth + i].offset_1d);
select = *((float*)sample_ptr + 2);
}
else {
light_set.light_1d = NULL;
light_set.light_2d = NULL;
bsdf_set.bsdf_1d = NULL;
bsdf_set.bsdf_2d = NULL;
path_sample.r1 = rng.random();
path_sample.r2 = rng.random();
path_sample.c = rng.random();
select = -1;
}
new_path_l = path_weight * uniform_sample_one_light(scene_ptr, bsdf_ptr, p, n,
wo, select, &light_set, &bsdf_set, rng);
L += new_path_l;
Vector3 wi;
float path_pdf;
BxDFType flags;
Color3 f = bsdf_ptr->sample_f(wo, path_sample.r1,path_sample.r2, path_sample.c,
&wi, n, &path_pdf, BSDF_ALL, &flags);
if (f == Color3::Black() || path_pdf < 1e-3)
break;
specular_bounce = (flags & BSDF_SPECULAR) > 0;
bsdf_factor = f * std::fabs(dot(n, wi)) / path_pdf;
weight_records[i] = bsdf_factor;
path_weight *= bsdf_factor;
if (i >= sample_depth) {
// TODO : how to determine the prob?
float continue_prob = std::min(0.5, path_weight.relative_luminance());
if (rng.random() > continue_prob)
break;
path_weight /= continue_prob;
}
else if (i >= max_depth) {
break;
}
Ray path_ray(p, wi);
if (!scene_ptr->hit(path_ray, 1e-3, BIG_NUMBER, path_record, true)) {
if (specular_bounce)
for (uint32_t i = 0; i < scene_ptr->num_lights(); i++)
L += path_weight * scene_ptr->get_lights()[i]->Le(path_ray);
break;
}
current_ray.e = path_ray.e;
current_ray.d = path_ray.d;
current_h_ptr = &path_record;
}
}
L /= num_per_path;
return L;
}
rose::Spectrum rose::PathTracerIntegrator::IncomingRadiance(const rose::Ray &ray,
const rose::RayInterval &interval,
const rose::Scene &scene,
uint32_t) const {
// Final incoming radiance and accumulation value
Spectrum L(0.f), beta(1.f);
Ray current_ray(ray);
RayInterval current_interval(interval);
bool specular_bounce = false;
uint32_t bounces;
// Keep track of specular bounce
for (bounces = 0;; ++bounces) {
SurfaceInteraction interaction;
bool found_interaction = scene.Intersect(current_ray, current_interval, &interaction);
// Possibly add emission
if (bounces == 0 || specular_bounce) {
// Add emitted light
if (found_interaction) {
L += beta * interaction.Le(Normalize(-current_ray.Direction()));
} else {
for (const auto &light : scene.Lights()) {
L += beta * light->Le(current_ray);
}
}
}
// Terminate path if ray escaped or max depth reached
if (!found_interaction || bounces >= max_depth) { break; }
// Compute scattering function
std::unique_ptr<BSDF> bsdf = interaction.CreateBSDF(true);
// Get shading variables
const Vector3f n = interaction.sh_frame.N();
const Vector3f wo = Normalize(-current_ray.Direction());
// Loop over all lights and add direct contribution
for (const auto &light : scene.Lights()) {
// Sample light
LightSample light_sample;
OcclusionTester occlusion_tester;
Spectrum Li = light->SampleLi(interaction, sampler->Next2D(), &light_sample, &occlusion_tester);
// Check light return
if (Li.IsBlack() || light_sample.pdf == 0.f) { continue; }
// Evaluate BSDF
Spectrum f = bsdf->F(wo, light_sample.wi);
if (!f.IsBlack() && occlusion_tester.Unoccluded(scene)) {
L += beta * f * Li * AbsDotProduct(n, light_sample.wi) / light_sample.pdf;
}
}
// Sample BSDF to get new path
BXDFSample bsdf_sample;
Spectrum f = bsdf->SampleF(wo, sampler->Next2D(), &bsdf_sample);
if (f.IsBlack() || bsdf_sample.pdf == 0.f) { break; }
// Update beta
beta *= f * AbsDotProduct(bsdf_sample.wi, n) / bsdf_sample.pdf;
// Check if bounce is specular
specular_bounce = (bsdf_sample.sampled_type & SPECULAR) != 0;
// Compute new ray
current_ray = interaction.SpawnRay(bsdf_sample.wi);
// Possibly terminate path with Russian roulette
if (bounces > 3) {
float q = std::max(0.05f, 1.f - beta.Norm());
if (sampler->Next1D() < q) { break; }
beta /= 1.f - q;
}
}
return L;
}
Spectrum PathTracer::Integration (
const Scene * thisScene,
const Ray & ray
)
{
Spectrum intensity;
Attenuation throughput;
throughput.resetOne();
Intersection intersectionInfo;
double cos_i = 0;
double pdf = 1;
double rr = 1;
Ray current_ray( ray.origin, ray.direction );
size_t current_depth = 0;
while ( !( current_depth == maxDepth ) )
{
if ( !thisScene->IntersectionWithScene( current_ray, intersectionInfo ) )
break;
Objects * obj = intersectionInfo.object;
if ( obj->emitter )
{
intensity +=
Attenuate_Light_Spectrum(
throughput,
obj->emission
);
}
BRDFModels * brdf = obj->brdf_model;
// Get surface (macro) normal direction
Vector geometryNormalDirection;
geometryNormalDirection = intersectionInfo.normal;
Vector sampledNextDirection( 0, 0, 0 );
Attenuation attenuationFactor;
attenuationFactor = brdf->SampleBRDF(
current_ray.direction,
sampledNextDirection,
geometryNormalDirection,
pdf
);
// double randnum = getUniformRandomNumber ( 0.0 , 0.99 );
// if ( randnum < rr)
// break;
attenuationFactor.Scaled_by_Spectrum_Value( obj->material_type->color );
cos_i = AbsDot( sampledNextDirection, geometryNormalDirection );
throughput = throughput * ( attenuationFactor * ( cos_i / ( rr * pdf ) ) );
// update ray
current_ray.origin = intersectionInfo.intersectionPoint;
current_ray.direction = sampledNextDirection;
current_depth++;
}
return intensity;
}
