void HitPoints::TraceEyePath(HitPoint *hp, const Sample &sample, float const invPixelPdf)
{
HitPointEyePass *hpep = &hp->eyePass;
Scene &scene(*renderer->scene);
const bool includeEnvironment = renderer->sppmi->includeEnvironment;
const u_int maxDepth = renderer->sppmi->maxEyePathDepth;
//--------------------------------------------------------------------------
// Following code is, given or taken, a copy of path integrator Li() method
//--------------------------------------------------------------------------
// Declare common path integration variables
const SpectrumWavelengths &sw(sample.swl);
Ray ray;
const float rayWeight = sample.camera->GenerateRay(scene, sample, &ray, &(hp->imageX), &(hp->imageY));
const float nLights = scene.lights.size();
const u_int lightGroupCount = scene.lightGroups.size();
vector<SWCSpectrum> Ld(lightGroupCount, 0.f);
// Direct lighting samples variance
vector<float> Vd(lightGroupCount, 0.f);
SWCSpectrum pathThroughput(1.0f); // pathThroughput is normalised perpixel for the eyepass contribution, so no need for invPixelPdf normalisation;
vector<SWCSpectrum> L(lightGroupCount, 0.f);
vector<float> V(lightGroupCount, 0.f);
float VContrib = .1f;
bool scattered = false;
hpep->alpha = 1.f;
hpep->distance = INFINITY;
u_int vertexIndex = 0;
const Volume *volume = NULL;
bool specularBounce = true;
const bool enableDirectLightSampling = renderer->sppmi->directLightSampling;
for (u_int pathLength = 0; ; ++pathLength) {
const SWCSpectrum prevThroughput(pathThroughput);
float *data = eyeSampler->GetLazyValues(sample, 0, pathLength);
// Find next vertex of path
Intersection isect;
BSDF *bsdf;
float spdf;
sample.arena.Begin();
if (!scene.Intersect(sample, volume, scattered, ray, data[0],
&isect, &bsdf, &spdf, NULL, &pathThroughput)) {
pathThroughput /= spdf;
// Dade - now I know ray.maxt and I can call volumeIntegrator
SWCSpectrum Lv;
u_int g = scene.volumeIntegrator->Li(scene, ray, sample,
&Lv, &hpep->alpha);
if (!Lv.Black()) {
Lv *= prevThroughput;
L[g] += Lv;
}
// Stop path sampling since no intersection was found
// Possibly add horizon in render & reflections
if (!enableDirectLightSampling || (
(includeEnvironment || vertexIndex > 0) && specularBounce)) {
BSDF *ibsdf;
for (u_int i = 0; i < nLights; ++i) {
SWCSpectrum Le(pathThroughput);
if (scene.lights[i]->Le(scene, sample,
ray, &ibsdf, NULL, NULL, &Le))
L[scene.lights[i]->group] += Le;
}
}
// Set alpha channel
if (vertexIndex == 0)
hpep->alpha = 0.f;
hp->SetConstant();
break;
}
sample.arena.End();
scattered = bsdf->dgShading.scattered;
pathThroughput /= spdf;
if (vertexIndex == 0)
hpep->distance = ray.maxt * ray.d.Length();
SWCSpectrum Lv;
const u_int g = scene.volumeIntegrator->Li(scene, ray, sample,
&Lv, &hpep->alpha);
if (!Lv.Black()) {
Lv *= prevThroughput;
L[g] += Lv;
}
// Possibly add emitted light at path vertex
Vector wo(-ray.d);
if (specularBounce) {
BSDF *ibsdf;
SWCSpectrum Le(pathThroughput);
if (isect.Le(sample, ray, &ibsdf, NULL, NULL, &Le)) {
L[isect.arealight->group] += Le;
V[isect.arealight->group] += Le.Filter(sw) * VContrib;
}
}
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
// Estimate direct lighting
if (renderer->sppmi->directLightSampling && (nLights > 0)) {
for (u_int i = 0; i < lightGroupCount; ++i) {
Ld[i] = 0.f;
Vd[i] = 0.f;
}
renderer->sppmi->hints.SampleLights(scene, sample, p, n,
wo, bsdf, pathLength, pathThroughput, Ld, &Vd);
for (u_int i = 0; i < lightGroupCount; ++i) {
L[i] += Ld[i];
V[i] += Vd[i] * VContrib;
}
}
// Choose between storing or bouncing the hitpoint on the surface
bool const has_store_component = bsdf->NumComponents(store_component) > 0;
bool const has_bounce_component = bsdf->NumComponents(bounce_component) > 0;
float pdf_event;
bool store;
if (has_store_component && has_bounce_component)
{
// There is both bounce and store component, we choose with a
// random number
// TODO: do this by importance
store = data[4] < .5f;
pdf_event = 0.5;
}
else
{
// If there is only bounce/store component, we bounce/store
// accordingly
store = has_store_component;
pdf_event = 1.f;
}
if(store)
{
hp->SetSurface();
hpep->pathThroughput = pathThroughput * rayWeight / pdf_event * invPixelPdf;
hpep->wo = wo;
hpep->bsdf = bsdf;
hpep->single = sw.single;
sample.arena.Commit();
break;
}
// Sample BSDF to get new path direction
Vector wi;
float pdf;
BxDFType flags;
SWCSpectrum f;
if (pathLength == maxDepth || !bsdf->SampleF(sw, wo, &wi,
data[1], data[2], data[3], &f, &pdf, bounce_component, &flags,
NULL, true)) {
hp->SetConstant();
break;
}
if (flags != (BSDF_TRANSMISSION | BSDF_SPECULAR) ||
!(bsdf->Pdf(sw, wi, wo, BxDFType(BSDF_TRANSMISSION | BSDF_SPECULAR)) > 0.f))
{
++vertexIndex;
specularBounce = (flags & BSDF_SPECULAR) != 0;
}
pathThroughput *= f / pdf_event;
if (pathThroughput.Black()) {
hp->SetConstant();
break;
}
ray = Ray(p, wi);
ray.time = sample.realTime;
volume = bsdf->GetVolume(wi);
}
for(unsigned int i = 0; i < lightGroupCount; ++i)
{
if (!L[i].Black())
V[i] /= L[i].Filter(sw);
sample.AddContribution(hp->imageX, hp->imageY,
XYZColor(sw, L[i]) * rayWeight, hp->eyePass.alpha, hp->eyePass.distance,
0, renderer->sppmi->bufferEyeId, i);
}
}
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;
}
