void PathCPURenderThread::DirectLightSampling(
const float u0, const float u1, const float u2,
const float u3, const float u4,
const Spectrum &pathThrouput, const BSDF &bsdf,
const int depth, Spectrum *radiance) {
PathCPURenderEngine *engine = (PathCPURenderEngine *)renderEngine;
Scene *scene = engine->renderConfig->scene;
if (!bsdf.IsDelta()) {
// Pick a light source to sample
float lightPickPdf;
const LightSource *light = scene->SampleAllLights(u0, &lightPickPdf);
Vector lightRayDir;
float distance, directPdfW;
Spectrum lightRadiance = light->Illuminate(scene, bsdf.hitPoint,
u1, u2, u3, &lightRayDir, &distance, &directPdfW);
if (!lightRadiance.Black()) {
BSDFEvent event;
float bsdfPdfW;
Spectrum bsdfEval = bsdf.Evaluate(lightRayDir, &event, &bsdfPdfW);
if (!bsdfEval.Black()) {
const float epsilon = Max(MachineEpsilon::E(bsdf.hitPoint), MachineEpsilon::E(distance));
Ray shadowRay(bsdf.hitPoint, lightRayDir,
epsilon,
distance - epsilon);
RayHit shadowRayHit;
BSDF shadowBsdf;
Spectrum connectionThroughput;
// Check if the light source is visible
if (!scene->Intersect(device, false, u4, &shadowRay,
&shadowRayHit, &shadowBsdf, &connectionThroughput)) {
const float cosThetaToLight = AbsDot(lightRayDir, bsdf.shadeN);
const float directLightSamplingPdfW = directPdfW * lightPickPdf;
const float factor = cosThetaToLight / directLightSamplingPdfW;
if (depth >= engine->rrDepth) {
// Russian Roulette
bsdfPdfW *= Max(bsdfEval.Filter(), engine->rrImportanceCap);
}
// MIS between direct light sampling and BSDF sampling
const float weight = PowerHeuristic(directLightSamplingPdfW, bsdfPdfW);
*radiance += (weight * factor) * pathThrouput * connectionThroughput * lightRadiance * bsdfEval;
}
}
}
}
}
void PathHybridState::DirectLightSampling(const PathHybridRenderThread *renderThread,
const float u0, const float u1, const float u2,
const float u3, const BSDF &bsdf) {
if (!bsdf.IsDelta()) {
PathHybridRenderEngine *renderEngine = (PathHybridRenderEngine *)renderThread->renderEngine;
Scene *scene = renderEngine->renderConfig->scene;
// Pick a light source to sample
float lightPickPdf;
const LightSource *light = scene->SampleAllLights(u0, &lightPickPdf);
Vector lightRayDir;
float distance, directPdfW;
Spectrum lightRadiance = light->Illuminate(*scene, bsdf.hitPoint.p,
u1, u2, u3, &lightRayDir, &distance, &directPdfW);
if (!lightRadiance.Black()) {
BSDFEvent event;
float bsdfPdfW;
Spectrum bsdfEval = bsdf.Evaluate(lightRayDir, &event, &bsdfPdfW);
if (!bsdfEval.Black()) {
const float epsilon = Max(MachineEpsilon::E(bsdf.hitPoint.p), MachineEpsilon::E(distance));
directLightRay = Ray(bsdf.hitPoint.p, lightRayDir,
epsilon, distance - epsilon);
const float cosThetaToLight = AbsDot(lightRayDir, bsdf.hitPoint.shadeN);
const float directLightSamplingPdfW = directPdfW * lightPickPdf;
const float factor = cosThetaToLight / directLightSamplingPdfW;
if (depth >= renderEngine->rrDepth) {
// Russian Roulette
bsdfPdfW *= RenderEngine::RussianRouletteProb(bsdfEval, renderEngine->rrImportanceCap);
}
// MIS between direct light sampling and BSDF sampling
const float weight = PowerHeuristic(directLightSamplingPdfW, bsdfPdfW);
directLightRadiance = (weight * factor) * throuput * lightRadiance * bsdfEval;
} else
directLightRadiance = Spectrum();
} else
directLightRadiance = Spectrum();
} else
directLightRadiance = Spectrum();
}
