void PathCPURenderThread::DirectHitInfiniteLight(
const bool lastSpecular, const Spectrum &pathThrouput,
const Vector &eyeDir, const float lastPdfW, Spectrum *radiance) {
PathCPURenderEngine *engine = (PathCPURenderEngine *)renderEngine;
Scene *scene = engine->renderConfig->scene;
// Infinite light
float directPdfW;
if (scene->envLight) {
const Spectrum envRadiance = scene->envLight->GetRadiance(scene, -eyeDir, &directPdfW);
if (!envRadiance.Black()) {
if(!lastSpecular) {
// MIS between BSDF sampling and direct light sampling
*radiance += pathThrouput * PowerHeuristic(lastPdfW, directPdfW) * envRadiance;
} else
*radiance += pathThrouput * envRadiance;
}
}
// Sun light
if (scene->sunLight) {
const Spectrum sunRadiance = scene->sunLight->GetRadiance(scene, -eyeDir, &directPdfW);
if (!sunRadiance.Black()) {
if(!lastSpecular) {
// MIS between BSDF sampling and direct light sampling
*radiance += pathThrouput * PowerHeuristic(lastPdfW, directPdfW) * sunRadiance;
} else
*radiance += pathThrouput * sunRadiance;
}
}
}
Spectrum EstimateDirect(const Scene *scene, const Renderer *renderer,
MemoryArena &arena, const Light *light, const Point &p,
const Normal &n, const Vector &wo, float rayEpsilon, float time,
const BSDF *bsdf, RNG &rng, const LightSample &lightSample,
const BSDFSample &bsdfSample, BxDFType flags) {
Spectrum Ld(0.);
// Sample light source with multiple importance sampling
Vector wi;
float lightPdf, bsdfPdf;
VisibilityTester visibility;
Spectrum Li = light->Sample_L(p, rayEpsilon, lightSample, time,
&wi, &lightPdf, &visibility);
if (lightPdf > 0. && !Li.IsBlack()) {
Spectrum f = bsdf->f(wo, wi, flags);
if (!f.IsBlack() && visibility.Unoccluded(scene)) {
// Add light's contribution to reflected radiance
Li *= visibility.Transmittance(scene, renderer, NULL, rng, arena);
if (light->IsDeltaLight())
Ld += f * Li * (AbsDot(wi, n) / lightPdf);
else {
bsdfPdf = bsdf->Pdf(wo, wi, flags);
float weight = PowerHeuristic(1, lightPdf, 1, bsdfPdf);
Ld += f * Li * (AbsDot(wi, n) * weight / lightPdf);
}
}
}
// Sample BSDF with multiple importance sampling
if (!light->IsDeltaLight()) {
BxDFType sampledType;
Spectrum f = bsdf->Sample_f(wo, &wi, bsdfSample, &bsdfPdf, flags,
&sampledType);
if (!f.IsBlack() && bsdfPdf > 0.) {
float weight = 1.f;
if (!(sampledType & BSDF_SPECULAR)) {
lightPdf = light->Pdf(p, wi);
if (lightPdf == 0.)
return Ld;
weight = PowerHeuristic(1, bsdfPdf, 1, lightPdf);
}
// Add light contribution from BSDF sampling
Intersection lightIsect;
Spectrum Li(0.f);
RayDifferential ray(p, wi, rayEpsilon, INFINITY, time);
if (scene->Intersect(ray, &lightIsect)) {
if (lightIsect.primitive->GetAreaLight() == light)
Li = lightIsect.Le(-wi);
}
else
//Li = light->Le(ray,);
Li = Spectrum(0.);
if (!Li.IsBlack()) {
Li *= renderer->Transmittance(scene, ray, NULL, rng, arena);
Ld += f * Li * AbsDot(wi, n) * weight / bsdfPdf;
}
}
}
return Ld;
}
void PathCPURenderThread::DirectHitFiniteLight(
const bool lastSpecular, const Spectrum &pathThrouput,
const float distance, const BSDF &bsdf, const float lastPdfW,
Spectrum *radiance) {
PathCPURenderEngine *engine = (PathCPURenderEngine *)renderEngine;
Scene *scene = engine->renderConfig->scene;
float directPdfA;
const Spectrum emittedRadiance = bsdf.GetEmittedRadiance(scene, &directPdfA);
if (!emittedRadiance.Black()) {
float weight;
if (!lastSpecular) {
const float lightPickProb = scene->PickLightPdf();
const float directPdfW = PdfAtoW(directPdfA, distance,
AbsDot(bsdf.fixedDir, bsdf.shadeN));
// MIS between BSDF sampling and direct light sampling
weight = PowerHeuristic(lastPdfW, directPdfW * lightPickProb);
} else
weight = 1.f;
*radiance += pathThrouput * weight * emittedRadiance;
}
}
float ComputeHeuristic(float fpdf, float gpdf)
{
#if 0
return BalanceHeuristic(fpdf, gpdf);
#else
return PowerHeuristic(fpdf, gpdf);
#endif
}
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;
}
}
}
}
}
// MIS: sampling BRDF
glm::vec3 BidirectionalIntegrator::MIS_SampleBRDF(Intersection &intersection, Ray &r, Geometry* &light)
{
if(Number_BRDF == 0)
return glm::vec3(0);
// Direct light estimator: sample BRDF
glm::vec3 sum_brdf_sample(0.0f);
for(int i = 0; i < Number_BRDF; i++)
{
glm::vec3 wo_local = intersection.ToLocalNormalCoordinate(-r.direction);
glm::vec3 wj_local;
float pdf_brdf;
glm::vec3 F = intersection.object_hit->material->SampleAndEvaluateScatteredEnergy(intersection,wo_local,wj_local,pdf_brdf);
glm::vec3 wj_world = intersection.ToWorldNormalCoordinate(wj_local);
glm::vec3 wo_world = - r.direction;
Intersection isxOnLight = intersection_engine->GetIntersection(Ray(intersection.point+float(1e-3)*intersection.normal, wj_world));
if(isxOnLight.t > 0 && isxOnLight.object_hit == light && pdf_brdf > 0)
{
float temp,pdf_light = light->RayPDF(intersection, Ray(intersection.point, wj_world));
float W = PowerHeuristic(pdf_brdf,float(Number_BRDF),pdf_light,float(Number_Light));
glm::vec3 Ld = light->material->EvaluateScatteredEnergy(isxOnLight,wo_world,-wj_world,temp);
if(pdf_light > 0 )
{
if(isinf(pdf_brdf)) // delta specular surface
{
sum_brdf_sample = sum_brdf_sample +
F * Ld * float(fabs(glm::dot(wj_world, intersection.normal))) / pdf_light;
}
else
{
sum_brdf_sample = sum_brdf_sample +
W * F * Ld * float(fabs(glm::dot(wj_world,intersection.normal))) / pdf_brdf;
}
}
}
}
return sum_brdf_sample / float(Number_BRDF);
}
// MIS: sampling light source
glm::vec3 BidirectionalIntegrator::MIS_SampleLight(Intersection &intersection, Ray &r, Geometry* &light)
{
if(Number_Light == 0)
return glm::vec3(0);
// Direct light estimator: sample Light source
glm::vec3 sum_light_sample(0);
for(int i = 0; i < Number_Light; i++)
{
float u = uniform_distribution(generator);
float v = uniform_distribution(generator);
Intersection lightSample = light->SampleOnGeometrySurface(u, v, intersection.point + 1e-3f * intersection.normal);
//Intersection lightSample = light->RandomSampleOnSurface(u,v);
glm::vec3 wj = glm::normalize(lightSample.point - intersection.point);
glm::vec3 wo = - r.direction;
glm::vec3 P = intersection.point;
glm::vec3 N = intersection.normal;
float pdf_light = light->RayPDF(intersection, Ray(P + float(1e-3)*N, wj));
Intersection lightIntersection = intersection_engine->GetIntersection(Ray(P + float(1e-3)*N, wj));
float temp, pdf_brdf;
glm::vec3 wo_local = intersection.ToLocalNormalCoordinate(wo);
glm::vec3 wj_local = intersection.ToLocalNormalCoordinate(wj);
glm::vec3 F = intersection.object_hit->material->EvaluateScatteredEnergy(intersection, wo_local, wj_local, pdf_brdf);
// reach light directly && pdf(wj) > 0
if(lightIntersection.t > 0 && lightIntersection.object_hit == light && pdf_light > 0 && pdf_brdf > 0)
{
glm::vec3 Ld = light->material->EvaluateScatteredEnergy(lightSample, wo, -wj, temp);
float W = PowerHeuristic(pdf_light, float(Number_Light), pdf_brdf, float(Number_BRDF)); // cause shadow in center
sum_light_sample = sum_light_sample +
W * F * Ld * float(fabs(glm::dot(wj, N))) / pdf_light;
}
}
return sum_light_sample / float(Number_Light);
}
Color RayTracer::EstimateDirect(const Scene *scene, const Ray& ray, const LocalGeo& geom, const Light *light, const Sample *lightsample, const Sample *bsdfsample){
Vec3 wo = -ray.dir; // dir to camera
Ray lightray;
float light_pdf, bsdf_pdf;
Color color, lightcolor, surfacecolor;
// sample light sources with multiple importance sampling
light->SampleDirect(geom.point, lightsample, &lightray, &lightcolor, &light_pdf);
if (light_pdf > 0.f && lightcolor != Color::BLACK){
surfacecolor = geom.bsdf->Eval(lightray.dir, wo, geom, BSDFType(BSDF_ALL & ~BSDF_SPECULAR));
if (surfacecolor != Color::BLACK && !scene->Occlude(lightray)){
if (light->IsDelta())
color = surfacecolor * lightcolor * (Math::AbsDot(lightray.dir, geom.normal));
else{
bsdf_pdf = geom.bsdf->Pdf(wo, lightray.dir, geom);
color = surfacecolor * lightcolor * (Math::AbsDot(lightray.dir, geom.normal) / light_pdf * PowerHeuristic(1, light_pdf, 1, bsdf_pdf));
}
}
}
if (light->IsDelta())
return color;
// sample bsdf with multiple importance sampling
surfacecolor = geom.bsdf->SampleDirect(wo, geom, *bsdfsample, &(lightray.dir), &bsdf_pdf, BSDFType(BSDF_ALL & ~BSDF_SPECULAR));
if (bsdf_pdf > 0.f && surfacecolor != Color::BLACK){
lightcolor = Color::BLACK;
LocalGeo geom_light;
if (scene->Intersect(lightray, geom_light)){
if (light == geom_light.prim->GetAreaLight()){
scene->PostIntersect(lightray, geom_light);
light_pdf = geom_light.prim->Pdf(geom_light.triId, geom.point, lightray.dir);
geom_light.Emit(-lightray.dir, &lightcolor);
}
}
//else
// light->Emit(lightray, &lightcolor);
if (lightcolor != Color::BLACK){
color += surfacecolor * lightcolor * (Math::AbsDot(lightray.dir, geom.normal) / bsdf_pdf * PowerHeuristic(1, bsdf_pdf, 1, light_pdf));
}
}
return color;
}
Spectrum PhotonIntegrator::Li(const Scene *scene, const Renderer *renderer,
const RayDifferential &ray, const Intersection &isect,
const Sample *sample, RNG &rng, MemoryArena &arena) const {
Spectrum L(0.);
Vector wo = -ray.d;
// Compute emitted light if ray hit an area light source
L += isect.Le(wo);
// Evaluate BSDF at hit pbrt::Point
BSDF *bsdf = isect.GetBSDF(ray, arena);
const pbrt::Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
L += UniformSampleAllLights(scene, renderer, arena, p, n,
wo, isect.rayEpsilon, ray.time, bsdf, sample, rng,
lightSampleOffsets, bsdfSampleOffsets);
// Compute caustic lighting for photon map integrator
ClosePhoton *lookupBuf = arena.Alloc<ClosePhoton>(nLookup);
L += LPhoton(causticMap, nCausticPaths, nLookup, lookupBuf, bsdf,
rng, isect, wo, maxDistSquared);
// Compute indirect lighting for photon map integrator
if (finalGather && indirectMap != NULL) {
#if 1
// Do one-bounce final gather for photon map
BxDFType nonSpecular = BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_DIFFUSE | BSDF_GLOSSY);
if (bsdf->NumComponents(nonSpecular) > 0) {
// Find indirect photons around point for importance sampling
const uint32_t nIndirSamplePhotons = 50;
PhotonProcess proc(nIndirSamplePhotons,
arena.Alloc<ClosePhoton>(nIndirSamplePhotons));
float searchDist2 = maxDistSquared;
while (proc.nFound < nIndirSamplePhotons) {
float md2 = searchDist2;
proc.nFound = 0;
indirectMap->Lookup(p, proc, md2);
searchDist2 *= 2.f;
}
// Copy photon directions to local array
Vector *photonDirs = arena.Alloc<Vector>(nIndirSamplePhotons);
for (uint32_t i = 0; i < nIndirSamplePhotons; ++i)
photonDirs[i] = proc.photons[i].photon->wi;
// Use BSDF to do final gathering
Spectrum Li = 0.;
for (int i = 0; i < gatherSamples; ++i) {
// Sample random direction from BSDF for final gather ray
Vector wi;
float pdf;
BSDFSample bsdfSample(sample, bsdfGatherSampleOffsets, i);
Spectrum fr = bsdf->Sample_f(wo, &wi, bsdfSample,
&pdf, BxDFType(BSDF_ALL & ~BSDF_SPECULAR));
if (fr.IsBlack() || pdf == 0.f) continue;
Assert(pdf >= 0.f);
// Trace BSDF final gather ray and accumulate radiance
RayDifferential bounceRay(p, wi, ray, isect.rayEpsilon);
Intersection gatherIsect;
if (scene->Intersect(bounceRay, &gatherIsect)) {
// Compute exitant radiance _Lindir_ using radiance photons
Spectrum Lindir = 0.f;
Normal nGather = gatherIsect.dg.nn;
nGather = Faceforward(nGather, -bounceRay.d);
RadiancePhotonProcess proc(nGather);
float md2 = INFINITY;
radianceMap->Lookup(gatherIsect.dg.p, proc, md2);
if (proc.photon != NULL)
Lindir = proc.photon->Lo;
Lindir *= renderer->Transmittance(scene, bounceRay, NULL, rng, arena);
// Compute MIS weight for BSDF-sampled gather ray
// Compute PDF for photon-sampling of direction _wi_
float photonPdf = 0.f;
float conePdf = UniformConePdf(cosGatherAngle);
for (uint32_t j = 0; j < nIndirSamplePhotons; ++j)
if (Dot(photonDirs[j], wi) > .999f * cosGatherAngle)
photonPdf += conePdf;
photonPdf /= nIndirSamplePhotons;
float wt = PowerHeuristic(gatherSamples, pdf, gatherSamples, photonPdf);
Li += fr * Lindir * (AbsDot(wi, n) * wt / pdf);
}
}
L += Li / gatherSamples;
// Use nearby photons to do final gathering
Li = 0.;
for (int i = 0; i < gatherSamples; ++i) {
// Sample random direction using photons for final gather ray
BSDFSample gatherSample(sample, indirGatherSampleOffsets, i);
int photonNum = min((int)nIndirSamplePhotons - 1,
Floor2Int(gatherSample.uComponent * nIndirSamplePhotons));
// Sample gather ray direction from _photonNum_
Vector vx, vy;
CoordinateSystem(photonDirs[photonNum], &vx, &vy);
Vector wi = UniformSampleCone(gatherSample.uDir[0], gatherSample.uDir[1],
cosGatherAngle, vx, vy, photonDirs[photonNum]);
// Trace photon-sampled final gather ray and accumulate radiance
Spectrum fr = bsdf->f(wo, wi);
if (fr.IsBlack()) continue;
RayDifferential bounceRay(p, wi, ray, isect.rayEpsilon);
Intersection gatherIsect;
PBRT_PHOTON_MAP_STARTED_GATHER_RAY(&bounceRay);
if (scene->Intersect(bounceRay, &gatherIsect)) {
// Compute exitant radiance _Lindir_ using radiance photons
Spectrum Lindir = 0.f;
Normal nGather = gatherIsect.dg.nn;
nGather = Faceforward(nGather, -bounceRay.d);
RadiancePhotonProcess proc(nGather);
float md2 = INFINITY;
radianceMap->Lookup(gatherIsect.dg.p, proc, md2);
if (proc.photon != NULL)
Lindir = proc.photon->Lo;
Lindir *= renderer->Transmittance(scene, bounceRay, NULL, rng, arena);
// Compute PDF for photon-sampling of direction _wi_
float photonPdf = 0.f;
float conePdf = UniformConePdf(cosGatherAngle);
for (uint32_t j = 0; j < nIndirSamplePhotons; ++j)
if (Dot(photonDirs[j], wi) > .999f * cosGatherAngle)
photonPdf += conePdf;
photonPdf /= nIndirSamplePhotons;
// Compute MIS weight for photon-sampled gather ray
float bsdfPdf = bsdf->Pdf(wo, wi);
float wt = PowerHeuristic(gatherSamples, photonPdf, gatherSamples, bsdfPdf);
Li += fr * Lindir * AbsDot(wi, n) * wt / photonPdf;
}
PBRT_PHOTON_MAP_FINISHED_GATHER_RAY(&bounceRay);
}
L += Li / gatherSamples;
}
#else
// for debugging / examples: use the photon map directly
Normal nn = Faceforward(n, -ray.d);
RadiancePhotonProcess proc(nn);
float md2 = INFINITY;
radianceMap->Lookup(p, proc, md2);
if (proc.photon)
L += proc.photon->Lo;
#endif
}
else
L += LPhoton(indirectMap, nIndirectPaths, nLookup, lookupBuf,
bsdf, rng, isect, wo, maxDistSquared);
if (ray.depth+1 < maxSpecularDepth) {
Vector wi;
// Trace rays for specular reflection and refraction
L += SpecularReflect(ray, bsdf, rng, isect, renderer, scene, sample,
arena);
L += SpecularTransmit(ray, bsdf, rng, isect, renderer, scene, sample,
arena);
}
return L;
}
Spectrum ExPhotonIntegrator::Li(const Scene *scene,
const RayDifferential &ray, const Sample *sample,
float *alpha) const {
// Compute reflected radiance with photon map
Spectrum L(0.);
Intersection isect;
if (scene->Intersect(ray, &isect)) {
if (alpha) *alpha = 1.;
Vector wo = -ray.d;
// Compute emitted light if ray hit an area light source
L += isect.Le(wo);
// Evaluate BSDF at hit point
BSDF *bsdf = isect.GetBSDF(ray);
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
L += UniformSampleAllLights(scene, p, n,
wo, bsdf, sample,
lightSampleOffset, bsdfSampleOffset,
bsdfComponentOffset);
// Compute indirect lighting for photon map integrator
L += LPhoton(causticMap, nCausticPaths, nLookup, bsdf,
isect, wo, maxDistSquared);
if (finalGather) {
#if 1
// Do one-bounce final gather for photon map
BxDFType nonSpecular = BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_DIFFUSE | BSDF_GLOSSY);
if (bsdf->NumComponents(nonSpecular) > 0) {
// Find indirect photons around point for importance sampling
u_int nIndirSamplePhotons = 50;
PhotonProcess proc(nIndirSamplePhotons, p);
proc.photons = (ClosePhoton *)alloca(nIndirSamplePhotons *
sizeof(ClosePhoton));
float searchDist2 = maxDistSquared;
while (proc.foundPhotons < nIndirSamplePhotons) {
float md2 = searchDist2;
proc.foundPhotons = 0;
indirectMap->Lookup(p, proc, md2);
searchDist2 *= 2.f;
}
// Copy photon directions to local array
Vector *photonDirs = (Vector *)alloca(nIndirSamplePhotons *
sizeof(Vector));
for (u_int i = 0; i < nIndirSamplePhotons; ++i)
photonDirs[i] = proc.photons[i].photon->wi;
// Use BSDF to do final gathering
Spectrum Li = 0.;
static StatsCounter gatherRays("Photon Map", // NOBOOK
"Final gather rays traced"); // NOBOOK
for (int i = 0; i < gatherSamples; ++i) {
// Sample random direction from BSDF for final gather ray
Vector wi;
float u1 = sample->twoD[gatherSampleOffset[0]][2*i];
float u2 = sample->twoD[gatherSampleOffset[0]][2*i+1];
float u3 = sample->oneD[gatherComponentOffset[0]][i];
float pdf;
Spectrum fr = bsdf->Sample_f(wo, &wi, u1, u2, u3,
&pdf, BxDFType(BSDF_ALL & (~BSDF_SPECULAR)));
if (fr.Black() || pdf == 0.f) continue;
// Trace BSDF final gather ray and accumulate radiance
RayDifferential bounceRay(p, wi);
++gatherRays; // NOBOOK
Intersection gatherIsect;
if (scene->Intersect(bounceRay, &gatherIsect)) {
// Compute exitant radiance using precomputed irradiance
Spectrum Lindir = 0.f;
Normal n = gatherIsect.dg.nn;
if (Dot(n, bounceRay.d) > 0) n = -n;
RadiancePhotonProcess proc(gatherIsect.dg.p, n);
float md2 = INFINITY;
radianceMap->Lookup(gatherIsect.dg.p, proc, md2);
if (proc.photon)
Lindir = proc.photon->Lo;
Lindir *= scene->Transmittance(bounceRay);
// Compute MIS weight for BSDF-sampled gather ray
// Compute PDF for photon-sampling of direction _wi_
float photonPdf = 0.f;
float conePdf = UniformConePdf(cosGatherAngle);
for (u_int j = 0; j < nIndirSamplePhotons; ++j)
if (Dot(photonDirs[j], wi) > .999f * cosGatherAngle)
photonPdf += conePdf;
photonPdf /= nIndirSamplePhotons;
float wt = PowerHeuristic(gatherSamples, pdf,
gatherSamples, photonPdf);
Li += fr * Lindir * AbsDot(wi, n) * wt / pdf;
}
}
L += Li / gatherSamples;
// Use nearby photons to do final gathering
Li = 0.;
for (int i = 0; i < gatherSamples; ++i) {
// Sample random direction using photons for final gather ray
float u1 = sample->oneD[gatherComponentOffset[1]][i];
float u2 = sample->twoD[gatherSampleOffset[1]][2*i];
float u3 = sample->twoD[gatherSampleOffset[1]][2*i+1];
int photonNum = min((int)nIndirSamplePhotons - 1,
Floor2Int(u1 * nIndirSamplePhotons));
// Sample gather ray direction from _photonNum_
Vector vx, vy;
CoordinateSystem(photonDirs[photonNum], &vx, &vy);
Vector wi = UniformSampleCone(u2, u3, cosGatherAngle, vx, vy,
photonDirs[photonNum]);
// Trace photon-sampled final gather ray and accumulate radiance
Spectrum fr = bsdf->f(wo, wi);
if (fr.Black()) continue;
// Compute PDF for photon-sampling of direction _wi_
float photonPdf = 0.f;
float conePdf = UniformConePdf(cosGatherAngle);
for (u_int j = 0; j < nIndirSamplePhotons; ++j)
if (Dot(photonDirs[j], wi) > .999f * cosGatherAngle)
photonPdf += conePdf;
photonPdf /= nIndirSamplePhotons;
RayDifferential bounceRay(p, wi);
++gatherRays; // NOBOOK
Intersection gatherIsect;
if (scene->Intersect(bounceRay, &gatherIsect)) {
// Compute exitant radiance using precomputed irradiance
Spectrum Lindir = 0.f;
Normal n = gatherIsect.dg.nn;
if (Dot(n, bounceRay.d) > 0) n = -n;
RadiancePhotonProcess proc(gatherIsect.dg.p, n);
float md2 = INFINITY;
radianceMap->Lookup(gatherIsect.dg.p, proc, md2);
if (proc.photon)
Lindir = proc.photon->Lo;
Lindir *= scene->Transmittance(bounceRay);
// Compute MIS weight for photon-sampled gather ray
float bsdfPdf = bsdf->Pdf(wo, wi);
float wt = PowerHeuristic(gatherSamples, photonPdf,
gatherSamples, bsdfPdf);
Li += fr * Lindir * AbsDot(wi, n) * wt / photonPdf;
}
}
L += Li / gatherSamples;
}
#else
// look at radiance map directly..
Normal nn = n;
if (Dot(nn, ray.d) > 0.) nn = -n;
RadiancePhotonProcess proc(p, nn);
float md2 = INFINITY;
radianceMap->Lookup(p, proc, md2);
if (proc.photon)
L += proc.photon->Lo;
#endif
}
else {
L += LPhoton(indirectMap, nIndirectPaths, nLookup,
bsdf, isect, wo, maxDistSquared);
}
if (specularDepth++ < maxSpecularDepth) {
Vector wi;
// Trace rays for specular reflection and refraction
Spectrum f = bsdf->Sample_f(wo, &wi,
BxDFType(BSDF_REFLECTION | BSDF_SPECULAR));
if (!f.Black()) {
// Compute ray differential _rd_ for specular reflection
RayDifferential rd(p, wi);
rd.hasDifferentials = true;
rd.rx.o = p + isect.dg.dpdx;
rd.ry.o = p + isect.dg.dpdy;
// Compute differential reflected directions
Normal dndx = bsdf->dgShading.dndu * bsdf->dgShading.dudx +
bsdf->dgShading.dndv * bsdf->dgShading.dvdx;
Normal dndy = bsdf->dgShading.dndu * bsdf->dgShading.dudy +
bsdf->dgShading.dndv * bsdf->dgShading.dvdy;
Vector dwodx = -ray.rx.d - wo, dwody = -ray.ry.d - wo;
float dDNdx = Dot(dwodx, n) + Dot(wo, dndx);
float dDNdy = Dot(dwody, n) + Dot(wo, dndy);
rd.rx.d = wi -
dwodx + 2 * Vector(Dot(wo, n) * dndx +
dDNdx * n);
rd.ry.d = wi -
dwody + 2 * Vector(Dot(wo, n) * dndy +
dDNdy * n);
L += scene->Li(rd, sample) * f * AbsDot(wi, n);
}
f = bsdf->Sample_f(wo, &wi,
BxDFType(BSDF_TRANSMISSION | BSDF_SPECULAR));
if (!f.Black()) {
// Compute ray differential _rd_ for specular transmission
RayDifferential rd(p, wi);
rd.hasDifferentials = true;
rd.rx.o = p + isect.dg.dpdx;
rd.ry.o = p + isect.dg.dpdy;
float eta = bsdf->eta;
Vector w = -wo;
if (Dot(wo, n) < 0) eta = 1.f / eta;
Normal dndx = bsdf->dgShading.dndu * bsdf->dgShading.dudx + bsdf->dgShading.dndv * bsdf->dgShading.dvdx;
Normal dndy = bsdf->dgShading.dndu * bsdf->dgShading.dudy + bsdf->dgShading.dndv * bsdf->dgShading.dvdy;
Vector dwodx = -ray.rx.d - wo, dwody = -ray.ry.d - wo;
float dDNdx = Dot(dwodx, n) + Dot(wo, dndx);
float dDNdy = Dot(dwody, n) + Dot(wo, dndy);
float mu = eta * Dot(w, n) - Dot(wi, n);
float dmudx = (eta - (eta*eta*Dot(w,n))/Dot(wi, n)) * dDNdx;
float dmudy = (eta - (eta*eta*Dot(w,n))/Dot(wi, n)) * dDNdy;
rd.rx.d = wi + eta * dwodx - Vector(mu * dndx + dmudx * n);
rd.ry.d = wi + eta * dwody - Vector(mu * dndy + dmudy * n);
L += scene->Li(rd, sample) * f * AbsDot(wi, n);
}
}
--specularDepth;
}
else {
// Handle ray with no intersection
if (alpha) *alpha = 0.;
for (u_int i = 0; i < scene->lights.size(); ++i)
L += scene->lights[i]->Le(ray);
if (alpha && !L.Black()) *alpha = 1.;
return L;
}
return L;
}
Spectrum EstimateDirect(const Interaction &it, const Point2f &uScattering,
const Light &light, const Point2f &uLight,
const Scene &scene, Sampler &sampler,
MemoryArena &arena, bool handleMedia, bool specular) {
BxDFType bsdfFlags =
specular ? BSDF_ALL : BxDFType(BSDF_ALL & ~BSDF_SPECULAR);
Spectrum Ld(0.f);
// Sample light source with multiple importance sampling
Vector3f wi;
Float lightPdf = 0, scatteringPdf = 0;
VisibilityTester visibility;
Spectrum Li = light.Sample_Li(it, uLight, &wi, &lightPdf, &visibility);
if (lightPdf > 0 && !Li.IsBlack()) {
// Compute BSDF or phase function's value for light sample
Spectrum f;
if (it.IsSurfaceInteraction()) {
// Evaluate BSDF for light sampling strategy
const SurfaceInteraction &isect = (const SurfaceInteraction &)it;
f = isect.bsdf->f(isect.wo, wi, bsdfFlags) *
AbsDot(wi, isect.shading.n);
scatteringPdf = isect.bsdf->Pdf(isect.wo, wi, bsdfFlags);
} else {
// Evaluate phase function for light sampling strategy
const MediumInteraction &mi = (const MediumInteraction &)it;
Float p = mi.phase->p(mi.wo, wi);
f = Spectrum(p);
scatteringPdf = p;
}
if (!f.IsBlack()) {
// Compute effect of visibility for light source sample
if (handleMedia)
Li *= visibility.Tr(scene, sampler);
else if (!visibility.Unoccluded(scene))
Li = Spectrum(0.f);
// Add light's contribution to reflected radiance
if (!Li.IsBlack()) {
if (IsDeltaLight(light.flags))
Ld += f * Li / lightPdf;
else {
Float weight =
PowerHeuristic(1, lightPdf, 1, scatteringPdf);
Ld += f * Li * weight / lightPdf;
}
}
}
}
// Sample BSDF with multiple importance sampling
if (!IsDeltaLight(light.flags)) {
Spectrum f;
bool sampledSpecular = false;
if (it.IsSurfaceInteraction()) {
// Sample scattered direction for surface interactions
BxDFType sampledType;
const SurfaceInteraction &isect = (const SurfaceInteraction &)it;
f = isect.bsdf->Sample_f(isect.wo, &wi, uScattering, &scatteringPdf,
bsdfFlags, &sampledType);
f *= AbsDot(wi, isect.shading.n);
sampledSpecular = sampledType & BSDF_SPECULAR;
} else {
// Sample scattered direction for medium interactions
const MediumInteraction &mi = (const MediumInteraction &)it;
Float p = mi.phase->Sample_p(mi.wo, &wi, uScattering);
f = Spectrum(p);
scatteringPdf = p;
}
if (!f.IsBlack() && scatteringPdf > 0) {
// Account for light contributions along sampled direction _wi_
Float weight = 1;
if (!sampledSpecular) {
lightPdf = light.Pdf_Li(it, wi);
if (lightPdf == 0) return Ld;
weight = PowerHeuristic(1, scatteringPdf, 1, lightPdf);
}
// Find intersection and compute transmittance
SurfaceInteraction lightIsect;
Ray ray = it.SpawnRay(wi);
Spectrum Tr(1.f);
bool foundSurfaceInteraction =
handleMedia ? scene.IntersectTr(ray, sampler, &lightIsect, &Tr)
: scene.Intersect(ray, &lightIsect);
// Add light contribution from material sampling
Spectrum Li(0.f);
if (foundSurfaceInteraction) {
if (lightIsect.primitive->GetAreaLight() == &light)
Li = lightIsect.Le(-wi);
} else
Li = light.Le(ray);
if (!Li.IsBlack()) Ld += f * Li * Tr * weight / scatteringPdf;
}
}
return Ld;
}
float3 DiTracer::GetDi(World const& world, Light const& light, Sampler const& lightsampler, Sampler const& bsdfsampler, float3 const& wo, ShapeBundle::Hit& hit) const
{
float3 radiance;
// TODO: fix that later with correct heuristic
assert(lightsampler.num_samples() == bsdfsampler.num_samples());
// Sample light source first to apply MIS later
{
// Direction from the shading point to the light
float3 lightdir;
// PDF for BSDF sample
float bsdfpdf = 0.f;
// PDF for light sample
float lightpdf = 0.f;
// Sample numsamples times
int numsamples = lightsampler.num_samples();
// Allocate samples
std::vector<float2> lightsamples(numsamples);
std::vector<float2> bsdfsamples(numsamples);
// Generate samples
for (int i = 0; i < numsamples; ++i)
{
lightsamples[i] = lightsampler.Sample2D();
bsdfsamples[i] = bsdfsampler.Sample2D();
}
// Cache singularity flag to avoid virtual call in the loop below
bool singularlight = light.Singular();
// Fetch the material
Material const& mat = *world.materials_[hit.m];
// Start sampling
for (int i=0; i<numsamples; ++i)
{
lightpdf = 0.f;
bsdfpdf = 0.f;
// This is needed to support normal mapping.
// Original intersection needs to be kept around since bsdf might alter the normal
ShapeBundle::Hit hitlocal = hit;
// Sample light source
float3 le = light.GetSample(hitlocal, lightsamples[i], lightdir, lightpdf);
// Continue if intensity > 0 and there is non-zero probability of sampling the point
if (lightpdf > MINPDF && le.sqnorm() > 0.f)
{
// Normalize direction to light
float3 wi = normalize(lightdir);
// Calculate distance for shadow testing
float dist = sqrtf(lightdir.sqnorm());
// Spawn shadow ray
ray shadowray;
// From an intersection point
shadowray.o = hitlocal.p;
// Into evaluated direction
shadowray.d = wi;
// TODO: move ray epsilon into some global options object
shadowray.t = float2(0.01f, dist - 0.01f);
// Check for an occlusion
float shadow = world.Intersect(shadowray) ? 0.f : 1.f;
// If we are not in shadow
if (shadow > 0.f)
{
// Evaluate BSDF
float3 bsdf = mat.Evaluate(hitlocal, wi, wo);
// We can't apply MIS for singular lights, so use simple estimator
if (singularlight)
{
// Estimate with Monte-Carlo L(wo) = int{ Ld(wi, wo) * fabs(dot(n, wi)) * dwi }
radiance += le * bsdf * fabs(dot(hitlocal.n, wi)) * (1.f / lightpdf);
assert(!has_nans(radiance));
}
else
{
// Apply MIS
bsdfpdf = mat.GetPdf(hitlocal, wi, wo);
// Evaluate weight
float weight = PowerHeuristic(1, lightpdf, 1, bsdfpdf);
// Estimate with Monte-Carlo L(wo) = int{ Ld(wi, wo) * fabs(dot(n, wi)) * dwi }
radiance += le * bsdf * fabs(dot(hitlocal.n, wi)) * weight * (1.f / lightpdf);
assert(!has_nans(radiance));
}
}
}
// Sample BSDF if the light is not singular
if (!singularlight)
{
int bsdftype = 0;
float3 wi;
// Sample material
float3 bsdf = mat.Sample(hitlocal, bsdfsamples[i], wo, wi, bsdfpdf, bsdftype);
//assert(!has_nans(bsdf));
//assert(!has_nans(bsdfpdf < 1000000.f));
// Normalize wi
wi = normalize(wi);
// If something would be reflected
if (bsdf.sqnorm() > 0.f && bsdfpdf > MINPDF)
{
float weight = 1.f;
// Apply MIS if BSDF is not specular
if (! (bsdftype & Bsdf::SPECULAR))
{
// Evaluate light PDF
lightpdf = light.GetPdf(hitlocal, wi);
// If light PDF is zero skip to next sample
if (lightpdf < MINPDF)
{
continue;
}
// Apply heuristic
weight = PowerHeuristic(1, bsdfpdf, 1, lightpdf);
}
// Spawn shadow ray
ray shadowray;
// From an intersection point
shadowray.o = hitlocal.p;
// Into evaluated direction
shadowray.d = wi;
// TODO: move ray epsilon into some global options object
shadowray.t = float2(0.01f, 10000000.f);
// Cast the ray into the scene
ShapeBundle::Hit shadowhit;
float3 le(0.f, 0.f, 0.f);
// If the ray intersects the scene check if we have intersected this light
// TODO: move that to area light class
if (world.Intersect(shadowray, shadowhit))
{
// Only sample if this is our light
if ((Light const*)shadowhit.bundle->GetAreaLight() == &light)
{
Material const& lightmat = *world.materials_[shadowhit.m];
// Get material emission properties
ShapeBundle::Sample sampledata(shadowhit);
float3 d = sampledata.p - hitlocal.p;
// If the object facing the light compute emission
if (dot(sampledata.n, -wi) > 0.f)
{
// Emissive power with squared fallof
float d2inv = 1.f / d.sqnorm();
// Return emission characteristic of the material
le = lightmat.GetLe(sampledata, -wi) * d2inv;
}
}
}
else
{
// This is to give a chance for IBL to contribute
le = light.GetLe(shadowray);
}
if (le.sqnorm() > 0.f)
{
// Estimate with Monte-Carlo L(wo) = int{ Ld(wi, wo) * fabs(dot(n, wi)) * dwi }
radiance += le * bsdf * fabs(dot(hitlocal.n, wi)) * weight * (1.f / bsdfpdf);
//assert(!has_nans(radiance));
}
}
}
}
return (1.f / numsamples) * radiance;
}
}
Spectrum EstimateDirect(const Scene *scene,
const Light *light, const Point &p,
const Normal &n, const Vector &wo,
BSDF *bsdf, const Sample *sample, int lightSamp,
int bsdfSamp, int bsdfComponent, u_int sampleNum) {
Spectrum Ld(0.);
// Find light and BSDF sample values for direct lighting estimate
float ls1, ls2, bs1, bs2, bcs;
if (lightSamp != -1 && bsdfSamp != -1 &&
sampleNum < sample->n2D[lightSamp] &&
sampleNum < sample->n2D[bsdfSamp]) {
ls1 = sample->twoD[lightSamp][2*sampleNum];
ls2 = sample->twoD[lightSamp][2*sampleNum+1];
bs1 = sample->twoD[bsdfSamp][2*sampleNum];
bs2 = sample->twoD[bsdfSamp][2*sampleNum+1];
bcs = sample->oneD[bsdfComponent][sampleNum];
}
else {
ls1 = RandomFloat();
ls2 = RandomFloat();
bs1 = RandomFloat();
bs2 = RandomFloat();
bcs = RandomFloat();
}
// Sample light source with multiple importance sampling
Vector wi;
float lightPdf, bsdfPdf;
VisibilityTester visibility;
Spectrum Li = light->Sample_L(p, n,
ls1, ls2, &wi, &lightPdf, &visibility);
if (lightPdf > 0. && !Li.Black()) {
Spectrum f = bsdf->f(wo, wi);
if (!f.Black() && visibility.Unoccluded(scene)) {
// Add light's contribution to reflected radiance
Li *= visibility.Transmittance(scene);
if (light->IsDeltaLight())
Ld += f * Li * AbsDot(wi, n) / lightPdf;
else {
bsdfPdf = bsdf->Pdf(wo, wi);
float weight = PowerHeuristic(1, lightPdf, 1, bsdfPdf);
Ld += f * Li * AbsDot(wi, n) * weight / lightPdf;
}
}
}
// Sample BSDF with multiple importance sampling
if (!light->IsDeltaLight()) {
BxDFType flags = BxDFType(BSDF_ALL & ~BSDF_SPECULAR);
Spectrum f = bsdf->Sample_f(wo, &wi,
bs1, bs2, bcs, &bsdfPdf, flags);
if (!f.Black() && bsdfPdf > 0.) {
lightPdf = light->Pdf(p, n, wi);
if (lightPdf > 0.) {
// Add light contribution from BSDF sampling
float weight = PowerHeuristic(1, bsdfPdf, 1, lightPdf);
Intersection lightIsect;
Spectrum Li(0.f);
RayDifferential ray(p, wi);
if (scene->Intersect(ray, &lightIsect)) {
if (lightIsect.primitive->GetAreaLight() == light)
Li = lightIsect.Le(-wi);
}
else
Li = light->Le(ray);
if (!Li.Black()) {
Li *= scene->Transmittance(ray);
Ld += f * Li * AbsDot(wi, n) * weight / bsdfPdf;
}
}
}
}
return Ld;
}
