// Integrator Utility Functions
Spectrum UniformSampleAllLights(const Interaction &it, const Scene &scene,
MemoryArena &arena, Sampler &sampler,
const std::vector<int> &nLightSamples,
bool handleMedia) {
ProfilePhase p(Prof::DirectLighting);
Spectrum L(0.f);
for (size_t j = 0; j < scene.lights.size(); ++j) {
// Accumulate contribution of _j_th light to _L_
const std::shared_ptr<Light> &light = scene.lights[j];
int nSamples = nLightSamples[j];
const Point2f *uLightArray = sampler.Get2DArray(nSamples);
const Point2f *uScatteringArray = sampler.Get2DArray(nSamples);
if (!uLightArray || !uScatteringArray) {
// Use a single sample for illumination from _light_
Point2f uLight = sampler.Get2D();
Point2f uScattering = sampler.Get2D();
L += EstimateDirect(it, uScattering, *light, uLight, scene, sampler,
arena, handleMedia);
} else {
// Estimate direct lighting using sample arrays
Spectrum Ld(0.f);
for (int k = 0; k < nSamples; ++k)
Ld += EstimateDirect(it, uScatteringArray[k], *light,
uLightArray[k], scene, sampler, arena,
handleMedia);
L += Ld / nSamples;
}
}
return L;
}
Spectrum UniformSampleOneLight(const Scene *scene,
const Renderer *renderer, MemoryArena &arena, const Point &p,
const Normal &n, const Vector &wo, float rayEpsilon, float time,
BSDF *bsdf, const Sample *sample, RNG &rng, int lightNumOffset,
const LightSampleOffsets *lightSampleOffset,
const BSDFSampleOffsets *bsdfSampleOffset) {
// Randomly choose a single light to sample, _light_
int nLights = int(scene->lights.size());
if (nLights == 0) return Spectrum(0.);
int lightNum;
if (lightNumOffset != -1)
lightNum = Floor2Int(sample->oneD[lightNumOffset][0] * nLights);
else
lightNum = Floor2Int(rng.RandomFloat() * nLights);
lightNum = min(lightNum, nLights-1);
Light *light = scene->lights[lightNum];
// Initialize light and bsdf samples for single light sample
LightSample lightSample;
BSDFSample bsdfSample;
if (lightSampleOffset != NULL && bsdfSampleOffset != NULL) {
lightSample = LightSample(sample, *lightSampleOffset, 0);
bsdfSample = BSDFSample(sample, *bsdfSampleOffset, 0);
}
else {
lightSample = LightSample(rng);
bsdfSample = BSDFSample(rng);
}
return (float)nLights *
EstimateDirect(scene, renderer, arena, light, p, n, wo,
rayEpsilon, time, bsdf, rng, lightSample,
bsdfSample, BxDFType(BSDF_ALL & ~BSDF_SPECULAR));
}
// Integrator Utility Functions
Spectrum UniformSampleAllLights(const Scene *scene,
const Renderer *renderer, MemoryArena &arena, const Point &p,
const Normal &n, const Vector &wo, float rayEpsilon,
float time, BSDF *bsdf, const Sample *sample, RNG &rng,
const LightSampleOffsets *lightSampleOffsets,
const BSDFSampleOffsets *bsdfSampleOffsets) {
Spectrum L(0.);
for (uint32_t i = 0; i < scene->lights.size(); ++i) {
Light *light = scene->lights[i];
int nSamples = lightSampleOffsets ?
lightSampleOffsets[i].nSamples : 1;
// Estimate direct lighting from _light_ samples
Spectrum Ld(0.);
for (int j = 0; j < nSamples; ++j) {
// Find light and BSDF sample values for direct lighting estimate
LightSample lightSample;
BSDFSample bsdfSample;
if (lightSampleOffsets != NULL && bsdfSampleOffsets != NULL) {
lightSample = LightSample(sample, lightSampleOffsets[i], j);
bsdfSample = BSDFSample(sample, bsdfSampleOffsets[i], j);
}
else {
lightSample = LightSample(rng);
bsdfSample = BSDFSample(rng);
}
Ld += EstimateDirect(scene, renderer, arena, light, p, n, wo,
rayEpsilon, time, bsdf, rng, lightSample, bsdfSample,
BxDFType(BSDF_ALL & ~BSDF_SPECULAR));
}
L += Ld / nSamples;
}
return L;
}
static Spectrum L(const Scene *scene, const Renderer *renderer,
const Camera *camera, MemoryArena &arena, RNG &rng, int maxDepth,
bool ignoreDirect, const MLTSample &sample) {
// Generate camera ray from Metropolis sample
RayDifferential ray;
float cameraWeight = camera->GenerateRayDifferential(sample.cameraSample,
&ray);
Spectrum pathThroughput = cameraWeight, L = 0.;
bool specularBounce = false, allSpecular = true;
for (int pathLength = 0; pathLength < maxDepth; ++pathLength) {
// Find next intersection in Metropolis light path
Intersection isect;
if (!scene->Intersect(ray, &isect)) {
bool includeLe = ignoreDirect ? (specularBounce && !allSpecular) :
(pathLength == 0 || specularBounce);
if (includeLe)
for (uint32_t i = 0; i < scene->lights.size(); ++i)
L += pathThroughput * scene->lights[i]->Le(ray);
break;
}
if (ignoreDirect ? (specularBounce && !allSpecular) :
(specularBounce || pathLength == 0))
L += pathThroughput * isect.Le(-ray.d);
BSDF *bsdf = isect.GetBSDF(ray, arena);
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
Vector wo = -ray.d;
const PathSample &ps = sample.pathSamples[pathLength];
// Sample direct illumination for Metropolis path vertex
if (!ignoreDirect || pathLength > 0) {
LightSample lightSample(ps.lightDir0, ps.lightDir1, ps.lightNum0);
BSDFSample bsdfSample(ps.bsdfLightDir0, ps.bsdfLightDir1,
ps.bsdfLightComponent);
uint32_t lightNum = Floor2Int(ps.lightNum1 * scene->lights.size());
lightNum = min(lightNum, (uint32_t)(scene->lights.size()-1));
const Light *light = scene->lights[lightNum];
L += pathThroughput *
EstimateDirect(scene, renderer, arena, light, p, n, wo,
isect.rayEpsilon, sample.cameraSample.time, bsdf, rng,
lightSample, bsdfSample);
}
// Sample direction for outgoing Metropolis path direction
BSDFSample outgoingBSDFSample(ps.bsdfDir0, ps.bsdfDir1,
ps.bsdfComponent);
Vector wi;
float pdf;
BxDFType flags;
Spectrum f = bsdf->Sample_f(wo, &wi, outgoingBSDFSample,
&pdf, BSDF_ALL, &flags);
if (f.IsBlack() || pdf == 0.)
break;
specularBounce = (flags & BSDF_SPECULAR) != 0;
allSpecular &= specularBounce;
pathThroughput *= f * AbsDot(wi, n) / pdf;
ray = RayDifferential(p, wi, ray, isect.rayEpsilon);
//pathThroughput *= renderer->Transmittance(scene, ray, NULL, rng, arena);
}
return L;
}
COREDLL Spectrum WeightedSampleOneLight(const Scene *scene,
const Point &p, const Normal &n,
const Vector &wo, BSDF *bsdf,
const Sample *sample, int lightSampleOffset,
int lightNumOffset, int bsdfSampleOffset,
int bsdfComponentOffset, float *&avgY,
float *&avgYsample, float *&cdf,
float &overallAvgY) {
int nLights = int(scene->lights.size());
// Initialize _avgY_ array if necessary
if (!avgY) {
avgY = new float[nLights];
avgYsample = new float[nLights];
cdf = new float[nLights+1];
for (int i = 0; i < nLights; ++i)
avgY[i] = avgYsample[i] = 0.;
}
Spectrum L(0.);
if (overallAvgY == 0.) {
// Sample one light uniformly and initialize luminance arrays
L = UniformSampleOneLight(scene, p, n,
wo, bsdf, sample, lightSampleOffset,
lightNumOffset, bsdfSampleOffset,
bsdfComponentOffset);
float luminance = L.y();
overallAvgY = luminance;
for (int i = 0; i < nLights; ++i)
avgY[i] = luminance;
}
else {
// Choose _light_ according to average reflected luminance
float c, lightSampleWeight;
for (int i = 0; i < nLights; ++i)
avgYsample[i] = max(avgY[i], .1f * overallAvgY);
ComputeStep1dCDF(avgYsample, nLights, &c, cdf);
float t = SampleStep1d(avgYsample, cdf, c, nLights,
sample->oneD[lightNumOffset][0], &lightSampleWeight);
int lightNum = min(Float2Int(nLights * t), nLights-1);
Light *light = scene->lights[lightNum];
L = EstimateDirect(scene, light, p, n, wo, bsdf,
sample, lightSampleOffset, bsdfSampleOffset,
bsdfComponentOffset, 0);
// Update _avgY_ array with reflected radiance due to light
float luminance = L.y();
avgY[lightNum] =
ExponentialAverage(avgY[lightNum], luminance, .99f);
overallAvgY =
ExponentialAverage(overallAvgY, luminance, .999f);
L /= lightSampleWeight;
}
return L;
}
Spectrum UniformSampleOneLight(const Interaction &it, const Scene &scene,
MemoryArena &arena, Sampler &sampler,
bool handleMedia) {
ProfilePhase p(Prof::DirectLighting);
// Randomly choose a single light to sample, _light_
int nLights = int(scene.lights.size());
if (nLights == 0) return Spectrum(0.f);
int lightNum = std::min((int)(sampler.Get1D() * nLights), nLights - 1);
const std::shared_ptr<Light> &light = scene.lights[lightNum];
Point2f uLight = sampler.Get2D();
Point2f uScattering = sampler.Get2D();
return (Float)nLights * EstimateDirect(it, uScattering, *light, uLight,
scene, sampler, arena, handleMedia);
}
Spectrum MetropolisRenderer::Lpath(const Scene *scene,
const PathVertex *cameraPath, int cameraPathLength,
MemoryArena &arena, const vector<LightingSample> &samples,
RNG &rng, float time, const Distribution1D *lightDistribution,
const RayDifferential &eRay, const Spectrum &eAlpha) const {
PBRT_MLT_STARTED_LPATH();
Spectrum L = 0.;
bool previousSpecular = true, allSpecular = true;
for (int i = 0; i < cameraPathLength; ++i) {
// Initialize basic variables for camera path vertex
const PathVertex &vc = cameraPath[i];
const Point &pc = vc.bsdf->dgShading.p;
const Normal &nc = vc.bsdf->dgShading.nn;
// Add emitted light from vertex if appropriate
if (previousSpecular && (directLighting == NULL || !allSpecular))
L += vc.alpha * vc.isect.Le(vc.wPrev);
// Compute direct illumination for Metropolis path vertex
Spectrum Ld(0.f);
if (directLighting == NULL || !allSpecular) {
// Choose light and call _EstimateDirect()_ for Metropolis vertex
const LightingSample &ls = samples[i];
float lightPdf;
uint32_t lightNum = lightDistribution->SampleDiscrete(ls.lightNum,
&lightPdf);
const Light *light = scene->lights[lightNum];
PBRT_MLT_STARTED_ESTIMATE_DIRECT();
Ld = vc.alpha *
EstimateDirect(scene, this, arena, light, pc, nc, vc.wPrev,
vc.isect.rayEpsilon, time, vc.bsdf, rng, NULL,
ls.lightSample, ls.bsdfSample,
BxDFType(BSDF_ALL & ~BSDF_SPECULAR)) / lightPdf;
PBRT_MLT_FINISHED_ESTIMATE_DIRECT();
}
previousSpecular = vc.specularBounce;
allSpecular &= previousSpecular;
L += Ld;
}
// Add contribution of escaped ray, if any
if (!eAlpha.IsBlack() && previousSpecular &&
(directLighting == NULL || !allSpecular))
for (uint32_t i = 0; i < scene->lights.size(); ++i)
L += eAlpha * scene->lights[i]->Le(eRay);
PBRT_MLT_FINISHED_LPATH();
return L;
}
COREDLL Spectrum UniformSampleOneLight(const Scene *scene,
const Point &p, const Normal &n,
const Vector &wo, BSDF *bsdf, const Sample *sample,
int lightSampleOffset, int lightNumOffset,
int bsdfSampleOffset, int bsdfComponentOffset) {
// Randomly choose a single light to sample, _light_
int nLights = int(scene->lights.size());
int lightNum;
if (lightNumOffset != -1)
lightNum = Floor2Int(sample->oneD[lightNumOffset][0] *
nLights);
else
lightNum = Floor2Int(RandomFloat() * nLights);
lightNum = min(lightNum, nLights-1);
Light *light = scene->lights[lightNum];
return (float)nLights *
EstimateDirect(scene, light, p, n, wo, bsdf, sample,
lightSampleOffset, bsdfSampleOffset,
bsdfComponentOffset, 0);
}
// Integrator Utility Functions
COREDLL Spectrum UniformSampleAllLights(const Scene *scene,
const Point &p, const Normal &n, const Vector &wo,
BSDF *bsdf, const Sample *sample,
int *lightSampleOffset, int *bsdfSampleOffset,
int *bsdfComponentOffset) {
Spectrum L(0.);
for (u_int i = 0; i < scene->lights.size(); ++i) {
Light *light = scene->lights[i];
int nSamples = (sample && lightSampleOffset) ?
sample->n2D[lightSampleOffset[i]] : 1;
// Estimate direct lighting from _light_ samples
Spectrum Ld(0.);
for (int j = 0; j < nSamples; ++j)
Ld += EstimateDirect(scene, light, p, n, wo, bsdf,
sample, lightSampleOffset[i], bsdfSampleOffset[i],
bsdfComponentOffset[i], j);
L += Ld / nSamples;
}
return L;
}
Spectrum MetropolisRenderer::Lbidir(const Scene *scene,
const PathVertex *cameraPath, int cameraPathLength,
const PathVertex *lightPath, int lightPathLength,
MemoryArena &arena, const vector<LightingSample> &samples,
RNG &rng, float time, const Distribution1D *lightDistribution,
const RayDifferential &eRay, const Spectrum &eAlpha) const {
PBRT_MLT_STARTED_LBIDIR();
Spectrum L = 0.;
bool previousSpecular = true, allSpecular = true;
// Compute number of specular vertices for each path length
int nVerts = cameraPathLength + lightPathLength + 2;
int *nSpecularVertices = ALLOCA(int, nVerts);
memset(nSpecularVertices, 0, nVerts * sizeof(int));
for (int i = 0; i < cameraPathLength; ++i)
for (int j = 0; j < lightPathLength; ++j)
if (cameraPath[i].specularBounce || lightPath[j].specularBounce)
++nSpecularVertices[i+j+2];
for (int i = 0; i < cameraPathLength; ++i) {
// Initialize basic variables for camera path vertex
const PathVertex &vc = cameraPath[i];
const Point &pc = vc.bsdf->dgShading.p;
const Normal &nc = vc.bsdf->dgShading.nn;
// Compute reflected light at camera path vertex
// Add emitted light from vertex if appropriate
if (previousSpecular && (directLighting == NULL || !allSpecular))
L += vc.alpha * vc.isect.Le(vc.wPrev);
// Compute direct illumination for Metropolis path vertex
Spectrum Ld(0.f);
if (directLighting == NULL || !allSpecular) {
// Choose light and call _EstimateDirect()_ for Metropolis vertex
const LightingSample &ls = samples[i];
float lightPdf;
uint32_t lightNum = lightDistribution->SampleDiscrete(ls.lightNum,
&lightPdf);
const Light *light = scene->lights[lightNum];
PBRT_MLT_STARTED_ESTIMATE_DIRECT();
Ld = vc.alpha *
EstimateDirect(scene, this, arena, light, pc, nc, vc.wPrev,
vc.isect.rayEpsilon, time, vc.bsdf, rng, NULL,
ls.lightSample, ls.bsdfSample,
BxDFType(BSDF_ALL & ~BSDF_SPECULAR)) / lightPdf;
PBRT_MLT_FINISHED_ESTIMATE_DIRECT();
}
previousSpecular = vc.specularBounce;
allSpecular &= previousSpecular;
L += Ld / (i + 1 - nSpecularVertices[i+1]);
if (!vc.specularBounce) {
// Loop over light path vertices and connect to camera vertex
for (int j = 0; j < lightPathLength; ++j) {
const PathVertex &vl = lightPath[j];
const Point &pl = vl.bsdf->dgShading.p;
const Normal &nl = vl.bsdf->dgShading.nn;
if (!vl.specularBounce) {
// Compute contribution between camera and light vertices
Vector w = Normalize(pl - pc);
Spectrum fc = vc.bsdf->f(vc.wPrev, w) * (1 + vc.nSpecularComponents);
Spectrum fl = vl.bsdf->f(-w, vl.wPrev) * (1 + vl.nSpecularComponents);
if (fc.IsBlack() || fl.IsBlack()) continue;
Ray r(pc, pl - pc, 1e-3f, .999f, time);
if (!scene->IntersectP(r)) {
// Compute weight for bidirectional path, _pathWt_
float pathWt = 1.f / (i + j + 2 - nSpecularVertices[i+j+2]);
float G = AbsDot(nc, w) * AbsDot(nl, w) / DistanceSquared(pl, pc);
L += (vc.alpha * fc * G * fl * vl.alpha) * pathWt;
}
}
}
}
}
// Add contribution of escaped ray, if any
if (!eAlpha.IsBlack() && previousSpecular &&
(directLighting == NULL || !allSpecular))
for (uint32_t i = 0; i < scene->lights.size(); ++i)
L += eAlpha * scene->lights[i]->Le(eRay);
PBRT_MLT_FINISHED_LBIDIR();
return L;
}
