Color3 BidirPathTracing::connectToCamera(BidirPathState& lightState ,
const Vector3& hitPos , BSDF& bsdf)
{
Color3 res(0);
Camera& camera = scene.camera;
Vector3 dirToCamera = camera.pos - hitPos;
if (((-dirToCamera) ^ camera.forward) <= 0)
return res;
Real distEye2 = dirToCamera.sqrLength();
Real dist = std::sqrt(distEye2);
dirToCamera = dirToCamera / dist;
Real cosToCamera , bsdfDirPdf , bsdfRevPdf;
Color3 bsdfFactor = bsdf.f(scene , dirToCamera , cosToCamera ,
&bsdfDirPdf , &bsdfRevPdf);
if (bsdfFactor.isBlack())
return res;
bsdfRevPdf *= bsdf.continueProb;
Real cosAtCamera = ((-dirToCamera) ^ camera.forward);
Real imagePointToCameraDist = camera.imagePlaneDist / cosAtCamera;
Real imageToSolidAngleFactor = SQR(imagePointToCameraDist) / cosAtCamera;
Real imageToSurfaceFactor = imageToSolidAngleFactor * std::abs(cosToCamera) / distEye2;
Real cameraPdfA = imageToSurfaceFactor /* * 1.f */; // pixel area is 1
Real surfaceToImageFactor = 1.f / imageToSurfaceFactor;
// We divide the contribution by surfaceToImageFactor to convert the (already
// divided) pdf from surface area to image plane area, w.r.t. which the
// pixel integral is actually defined. We also divide by the number of samples
// this technique makes
res = (lightState.throughput | bsdfFactor) /
(lightPathNum * surfaceToImageFactor);
if (res.isBlack())
return res;
if (scene.occluded(hitPos , dirToCamera , camera.pos))
return Color3(0);
Real wLight = mis(cameraPdfA / lightPathNum) * (lightState.dVCM +
mis(bsdfRevPdf) * lightState.dVC);
Real weight = 1.f / (wLight + 1.f);
//fprintf(fp , "weight = %.6f\n" , weight);
return res * weight;
}
// we force to connect eye path to light path
Color3 BidirPathTracing::connectVertices(BidirPathState& lightState ,
BSDF& cameraBsdf , const Vector3& hitPos ,
BidirPathState& cameraState)
{
Vector3 dir = lightState.pos - hitPos;
Real dist2 = dir.sqrLength();
Real dist = std::sqrt(dist2);
dir = dir / dist;
Color3 res(0);
Real cosAtCamera , cameraBsdfDirPdf , cameraBsdfRevPdf;
Color3 cameraBsdfFactor = cameraBsdf.f(scene , dir , cosAtCamera ,
&cameraBsdfDirPdf , &cameraBsdfRevPdf);
if (cameraBsdfFactor.isBlack())
return res;
Real cameraContProb = cameraBsdf.continueProb;
cameraBsdfDirPdf *= cameraContProb;
cameraBsdfRevPdf *= cameraContProb;
Real cosAtLight , lightBsdfDirPdf , lightBsdfRevPdf;
Color3 lightBsdfFactor = lightState.bsdf.f(scene , -dir , cosAtLight ,
&lightBsdfDirPdf , &lightBsdfRevPdf);
if (lightBsdfFactor.isBlack())
return res;
Real lightContProb = lightState.bsdf.continueProb;
lightBsdfDirPdf *= lightContProb;
lightBsdfRevPdf *= lightContProb;
Real geometryTerm = cosAtLight * cosAtCamera / dist2;
if (cmp(geometryTerm) < 0)
return res;
Real cameraBsdfDirPdfArea = pdfWtoA(cameraBsdfDirPdf , dist , cosAtLight);
Real lightBsdfDirPdfArea = pdfWtoA(lightBsdfDirPdf , dist , cosAtCamera);
res = (cameraBsdfFactor | lightBsdfFactor) * geometryTerm;
if (res.isBlack() || scene.occluded(hitPos , dir ,
hitPos + dir * dist))
return Color3(0);
Real wLight = mis(cameraBsdfDirPdfArea) *
(lightState.dVCM + mis(lightBsdfRevPdf) * lightState.dVC);
Real wCamera = mis(lightBsdfDirPdfArea) *
(cameraState.dVCM + mis(cameraBsdfRevPdf) * cameraState.dVC);
Real weight = 1.f / (wLight + 1.f + wCamera);
return res * weight;
}
// WhittedIntegrator Method Definitions
Spectrum WhittedIntegrator::Li(const Scene *scene,
const Renderer *renderer, const RayDifferential &ray,
const Intersection &isect, const Sample *sample,
MemoryArena &arena) const {
Spectrum L(0.);
// Compute emitted and reflected light at ray intersection point
// Evaluate BSDF at hit point
BSDF *bsdf = isect.GetBSDF(ray, arena);
// Initialize common variables for Whitted integrator
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
Vector wo = -ray.d;
// Compute emitted light if ray hit an area light source
L += isect.Le(wo);
// Add contribution of each light source
Vector wi;
for (u_int i = 0; i < scene->lights.size(); ++i) {
VisibilityTester visibility;
float pdf;
Spectrum Li = scene->lights[i]->Sample_L(p, isect.rayEpsilon,
LightSample(*sample->rng), sample->time, &wi, &pdf, &visibility);
if (Li.IsBlack() || pdf == 0.f) continue;
Li /= pdf;
Spectrum f = bsdf->f(wo, wi);
if (!f.IsBlack() && visibility.Unoccluded(scene))
L += f * Li * AbsDot(wi, n) *
visibility.Transmittance(scene, renderer,
sample, NULL, arena);
}
if (ray.depth + 1 < maxDepth) {
// Trace rays for specular reflection and refraction
L += SpecularReflect(ray, bsdf, *sample->rng, isect, renderer,
scene, sample, arena);
L += SpecularTransmit(ray, bsdf, *sample->rng, isect, renderer,
scene, sample, arena);
}
return L;
}
void testMaterial(DifferentialGeometry &dg) {
float c1[] = {1.f,1.f,1.f};
Spectrum spec1 = RGBSpectrum::FromRGB(c1, SpectrumType::SPECTRUM_REFLECTANCE);
MatteMaterial *matte = new MatteMaterial(
new ConstantTexture<Spectrum>(spec1),
new ConstantTexture<float>(0.0f), NULL);
MemoryArena m;
BSDF* bsdf = matte->GetBSDF(dg, dg, m);
Vector woW = Point(-10,0,0) - dg.p;
Vector wiW = Point(-7,2,2) - dg.p;
// world vectors
Spectrum spec = bsdf->f(woW, wiW);
float rgb[3];
spec.ToRGB(rgb);
printf("spectrum %g %g %g\n", rgb[0], rgb[1], rgb[2]);
}
Spectrum IGIIntegrator::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 point
BSDF *bsdf = isect.GetBSDF(ray, arena);
const 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 indirect illumination with virtual lights
uint32_t lSet = min(uint32_t(sample->oneD[vlSetOffset][0] * nLightSets),
nLightSets-1);
for (uint32_t i = 0; i < virtualLights[lSet].size(); ++i) {
const VirtualLight &vl = virtualLights[lSet][i];
// Compute virtual light's tentative contribution _Llight_
float d2 = DistanceSquared(p, vl.p);
Vector wi = Normalize(vl.p - p);
float G = AbsDot(wi, n) * AbsDot(wi, vl.n) / d2;
G = min(G, gLimit);
Spectrum f = bsdf->f(wo, wi);
if (G == 0.f || f.IsBlack()) continue;
Spectrum Llight = f * G * vl.pathContrib / nLightPaths;
RayDifferential connectRay(p, wi, ray, isect.rayEpsilon,
sqrtf(d2) * (1.f - vl.rayEpsilon));
Llight *= renderer->Transmittance(scene, connectRay, NULL, rng, arena);
// Possibly skip virtual light shadow ray with Russian roulette
if (Llight.y() < rrThreshold) {
float continueProbability = .1f;
if (rng.RandomFloat() > continueProbability)
continue;
Llight /= continueProbability;
}
// Add contribution from _VirtualLight_ _vl_
if (!scene->IntersectP(connectRay))
L += Llight;
}
if (ray.depth < maxSpecularDepth) {
// Do bias compensation for bounding geometry term
int nSamples = (ray.depth == 0) ? nGatherSamples : 1;
for (int i = 0; i < nSamples; ++i) {
Vector wi;
float pdf;
BSDFSample bsdfSample = (ray.depth == 0) ?
BSDFSample(sample, gatherSampleOffset, i) : BSDFSample(rng);
Spectrum f = bsdf->Sample_f(wo, &wi, bsdfSample,
&pdf, BxDFType(BSDF_ALL & ~BSDF_SPECULAR));
if (!f.IsBlack() && pdf > 0.f) {
// Trace ray for bias compensation gather sample
float maxDist = sqrtf(AbsDot(wi, n) / gLimit);
RayDifferential gatherRay(p, wi, ray, isect.rayEpsilon, maxDist);
Intersection gatherIsect;
Spectrum Li = renderer->Li(scene, gatherRay, sample, rng, arena,
&gatherIsect);
if (Li.IsBlack()) continue;
// Add bias compensation ray contribution to radiance sum
float Ggather = AbsDot(wi, n) * AbsDot(-wi, gatherIsect.dg.nn) /
DistanceSquared(p, gatherIsect.dg.p);
if (Ggather - gLimit > 0.f && !isinf(Ggather)) {
float gs = (Ggather - gLimit) / Ggather;
L += f * Li * (AbsDot(wi, n) * gs / (nSamples * pdf));
}
}
}
}
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 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;
}
// WhittedIntegrator Method Definitions
Spectrum WhittedIntegrator::Li(const Scene *scene,
const RayDifferential &ray, const Sample *sample,
float *alpha) const {
Intersection isect;
Spectrum L(0.);
bool hitSomething;
// Search for ray-primitive intersection
hitSomething = scene->Intersect(ray, &isect);
if (!hitSomething) {
// 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;
}
else {
// Initialize _alpha_ for ray hit
if (alpha) *alpha = 1.;
// Compute emitted and reflected light at ray intersection point
// Evaluate BSDF at hit point
BSDF *bsdf = isect.GetBSDF(ray);
// Initialize common variables for Whitted integrator
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
Vector wo = -ray.d;
// Compute emitted light if ray hit an area light source
L += isect.Le(wo);
// Add contribution of each light source
Vector wi;
for (u_int i = 0; i < scene->lights.size(); ++i) {
VisibilityTester visibility;
Spectrum Li = scene->lights[i]->Sample_L(p, &wi, &visibility);
if (Li.Black()) continue;
Spectrum f = bsdf->f(wo, wi);
if (!f.Black() && visibility.Unoccluded(scene))
L += f * Li * AbsDot(wi, n) * visibility.Transmittance(scene);
}
if (rayDepth++ < maxDepth) {
// Trace rays for specular reflection and refraction
Spectrum f = bsdf->Sample_f(wo, &wi,
BxDFType(BSDF_REFLECTION | BSDF_SPECULAR));
if (!f.Black() && AbsDot(wi, n) > 0.f) {
// 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() && AbsDot(wi, n) > 0.f) {
// 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);
}
}
--rayDepth;
}
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 IGIIntegrator::Li(const Scene *scene,
const RayDifferential &ray, const Sample *sample,
float *alpha) const {
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 illumination with virtual lights
u_int lSet = min(u_int(sample->oneD[vlSetOffset][0] * nLightSets),
nLightSets-1);
for (u_int i = 0; i < virtualLights[lSet].size(); ++i) {
const VirtualLight &vl = virtualLights[lSet][i];
// Add contribution from _VirtualLight_ _vl_
// Ignore light if it's too close to current point
float d2 = DistanceSquared(p, vl.p);
//if (d2 < .8 * minDist2) continue;
float distScale = SmoothStep(.8 * minDist2, 1.2 * minDist2, d2);
// Compute virtual light's tentative contribution _Llight_
Vector wi = Normalize(vl.p - p);
Spectrum f = distScale * bsdf->f(wo, wi);
if (f.Black()) continue;
float G = AbsDot(wi, n) * AbsDot(wi, vl.n) / d2;
Spectrum Llight = indirectScale * f * G * vl.Le /
virtualLights[lSet].size();
Llight *= scene->Transmittance(Ray(p, vl.p - p));
// Possibly skip shadow ray with Russian roulette
if (Llight.y() < rrThreshold) {
float continueProbability = .1f;
if (RandomFloat() > continueProbability)
continue;
Llight /= continueProbability;
}
static StatsCounter vlsr("IGI Integrator", "Shadow Rays to Virtual Lights"); //NOBOOK
++vlsr; //NOBOOK
if (!scene->IntersectP(Ray(p, vl.p - p, RAY_EPSILON,
1.f - RAY_EPSILON)))
L += Llight;
}
// Trace rays for specular reflection and refraction
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;
}
// WhittedIntegrator [ surface integrator ] Method Definitions
Spectrum WhittedIntegrator::Li(const Scene *scene,
const Renderer *renderer, const RayDifferential &ray,
const Intersection &isect, const Sample *sample, RNG &rng,
MemoryArena &arena) const {
Spectrum L(0.);
// Compute emitted and reflected light at ray intersection point
// Evaluate BSDF at hit point
BSDF *bsdf = isect.GetBSDF(ray, arena); // return BSDF of the material of the hit primitive
// Initialize common variables for Whitted integrator
const pbrt::Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
Vector wo = -ray.d;
// Compute emitted light at the intersection point. The emiited light exists if
// the intersection occured at an area light source; otherwise, it is zero.
L += isect.Le(wo);
// Add contribution of each light source
for (uint32_t i = 0; i < scene->lights.size(); ++i) {
Vector wi;
float pdf;
VisibilityTester visibility;
Spectrum Li = scene->lights[i]->Sample_L(p, isect.rayEpsilon,
LightSample(rng), ray.time, &wi, &pdf, &visibility);
// if light is a delta light, then "reflection" direction wi is set to the light direction with pdf =1
if (Li.IsBlack() || pdf == 0.f) continue;
Spectrum f = bsdf->f(wo, wi);
//
// compute the fraction of light to be reflected from wi to wo.
// ONLY non-delta BXDF, e.g. Lambertian (diffuse reflection) contributes to f here.
if (!f.IsBlack() && visibility.Unoccluded(scene))
// bsdf indicates that some of the incident
// light from direction wi is in fact scattered to the direction wo
L += f * Li * AbsDot(wi, n) *
visibility.Transmittance(scene, renderer,
sample, rng, arena) / pdf;
}
// consider the specular reflection and the specular transmission;
// you can get this component only when the light sources are NOT delta distribution.
// there's no possible way that the peaks of the two delta distributions (the glass
// and the point light) match. it is not possible
// to get a highlight of a point light source in a mirror.
if (ray.depth + 1 < maxDepth) {
// 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;
}
Color3 BidirPathTracing::getDirectIllumination(BidirPathState& cameraState ,
const Vector3& hitPos , BSDF& bsdf)
{
Color3 res(0);
Real weight = 0.f;
int lightCount = scene.lights.size();
Real lightPickProb = 1.f / lightCount;
int lightId = (int)(rng.randFloat() * lightCount);
AbstractLight *light = scene.lights[lightId];
Vector3 dirToLight;
Real dist , directPdf , emissionPdf , cosAtLight , cosAtSurface;
int sampledBSDFType;
Color3 illu = light->illuminance(scene.sceneSphere ,
hitPos , rng.randVector3() , dirToLight , dist ,
directPdf , &emissionPdf , &cosAtLight);
Real bsdfDirPdf , bsdfRevPdf , cosToLight;
if (!illu.isBlack() && directPdf > 0)
{
Color3 bsdfFactor = bsdf.f(scene , dirToLight ,
cosToLight , &bsdfDirPdf , &bsdfRevPdf);
Color3 tmp;
if (!bsdfFactor.isBlack())
{
Real contProb = bsdf.continueProb;
bsdfDirPdf *= light->isDelta() ? 0.f : contProb;
bsdfRevPdf *= contProb;
tmp = (illu | bsdfFactor) * cosToLight / (directPdf * lightPickProb);
if (!tmp.isBlack() && !scene.occluded(hitPos , dirToLight ,
hitPos + dirToLight * dist))
{
Real wLight = mis(bsdfDirPdf) / mis(directPdf * lightPickProb);
Real wCamera = mis(emissionPdf * cosToLight / (directPdf * cosAtLight)) *
(cameraState.dVCM + mis(bsdfRevPdf) * cameraState.dVC);
weight = 1.f / (wLight + 1.f + wCamera);
//fprintf(fp , "weight = %.6f\n" , weight);
if (light->isDelta())
{
res = res + tmp;
}
else
{
Real _weight = mis(directPdf) /
(mis(directPdf) + mis(bsdfDirPdf));
res = res + tmp * _weight;
}
}
}
}
if (!light->isDelta())
{
Color3 bsdfFactor = bsdf.sample(scene , rng.randVector3() ,
dirToLight , directPdf , cosAtSurface , &sampledBSDFType);
if (!bsdfFactor.isBlack() && directPdf > 0)
{
Real weight = 1.f;
Real lightPdf;
if (!(sampledBSDFType & BSDF_SPECULAR))
{
illu = light->getRadiance(scene.sceneSphere , dirToLight , hitPos ,
&lightPdf , &emissionPdf);
if (cmp(lightPdf) == 0)
return res;
weight = mis(directPdf) /
(mis(directPdf) + mis(lightPdf));
}
Intersection lightInter;
Color3 tmp(0.f);
Ray ray(hitPos + dirToLight * EPS , dirToLight);
if (scene.intersect(ray , lightInter) != NULL)
{
if (lightInter.matId < 0)
{
if (light != scene.lights[-lightInter.matId - 1])
{
illu = Color3(0.f);
}
}
else
{
illu = Color3(0.f);
}
}
else
{
illu = Color3(0.f);
if (scene.background != NULL)
{
illu = getLightRadiance(scene.background ,
cameraState , Vector3(0) , ray.dir);
}
}
if (!illu.isBlack())
{
tmp = (illu | bsdfFactor) * cosAtSurface /
(directPdf);
res = res + tmp * weight;
}
}
}
return res * weight;
}
