Spectrum Li(const RayDifferential &r, RadianceQueryRecord &rRec) const {
/* Some aliases and local variables */
const Scene *scene = rRec.scene;
Intersection &its = rRec.its, bsdfIts;
RayDifferential ray(r);
LuminaireSamplingRecord lRec;
Spectrum Li(0.0f);
Point2 sample;
/* Perform the first ray intersection (or ignore if the
intersection has already been provided). */
if (!rRec.rayIntersect(ray)) {
/* If no intersection could be found, possibly return
radiance from a background luminaire */
if (rRec.type & RadianceQueryRecord::EEmittedRadiance)
return scene->LeBackground(ray);
else
return Spectrum(0.0f);
}
/* Possibly include emitted radiance if requested */
if (its.isLuminaire() && (rRec.type & RadianceQueryRecord::EEmittedRadiance))
Li += its.Le(-ray.d);
/* Include radiance from a subsurface integrator if requested */
if (its.hasSubsurface() && (rRec.type & RadianceQueryRecord::ESubsurfaceRadiance))
Li += its.LoSub(scene, rRec.sampler, -ray.d, rRec.depth);
const BSDF *bsdf = its.getBSDF(ray);
if (EXPECT_NOT_TAKEN(!bsdf)) {
/* The direct illumination integrator doesn't support
surfaces without a BSDF (e.g. medium transitions)
-- give up. */
return Li;
}
/* Leave here if direct illumination was not requested */
if (!(rRec.type & RadianceQueryRecord::EDirectSurfaceRadiance))
return Li;
/* ==================================================================== */
/* Luminaire sampling */
/* ==================================================================== */
bool adaptiveQuery = (rRec.extra & RadianceQueryRecord::EAdaptiveQuery);
Point2 *sampleArray;
size_t numLuminaireSamples = m_luminaireSamples,
numBSDFSamples = m_bsdfSamples;
Float fracLum = m_fracLum, fracBSDF = m_fracBSDF,
weightLum = m_weightLum, weightBSDF = m_weightBSDF;
if (rRec.depth > 1 || adaptiveQuery) {
/* This integrator is used recursively by another integrator.
Be less accurate as this sample will not directly be observed. */
numBSDFSamples = numLuminaireSamples = 1;
fracLum = fracBSDF = .5f;
weightLum = weightBSDF = 1.0f;
}
if (numLuminaireSamples > 1) {
sampleArray = rRec.sampler->next2DArray(numLuminaireSamples);
} else {
sample = rRec.nextSample2D(); sampleArray = &sample;
}
for (size_t i=0; i<numLuminaireSamples; ++i) {
/* Estimate the direct illumination if this is requested */
if (scene->sampleLuminaire(its.p, ray.time, lRec, sampleArray[i])) {
/* Allocate a record for querying the BSDF */
BSDFQueryRecord bRec(its, its.toLocal(-lRec.d));
/* Evaluate BSDF * cos(theta) */
const Spectrum bsdfVal = bsdf->eval(bRec);
if (!bsdfVal.isZero()) {
/* Calculate prob. of having sampled that direction
using BSDF sampling */
Float bsdfPdf = (lRec.luminaire->isIntersectable()
|| lRec.luminaire->isBackgroundLuminaire()) ?
bsdf->pdf(bRec) : 0;
/* Weight using the power heuristic */
const Float weight = miWeight(lRec.pdf * fracLum,
bsdfPdf * fracBSDF) * weightLum;
Li += lRec.value * bsdfVal * weight;
}
}
}
/* ==================================================================== */
/* BSDF sampling */
/* ==================================================================== */
if (numBSDFSamples > 1) {
sampleArray = rRec.sampler->next2DArray(numBSDFSamples);
} else {
sample = rRec.nextSample2D(); sampleArray = &sample;
}
for (size_t i=0; i<numBSDFSamples; ++i) {
/* Sample BSDF * cos(theta) */
BSDFQueryRecord bRec(its, rRec.sampler, ERadiance);
Float bsdfPdf;
Spectrum bsdfVal = bsdf->sample(bRec, bsdfPdf, sampleArray[i]);
if (bsdfVal.isZero())
continue;
/* Trace a ray in this direction */
Ray bsdfRay(its.p, its.toWorld(bRec.wo), ray.time);
if (scene->rayIntersect(bsdfRay, bsdfIts)) {
/* Intersected something - check if it was a luminaire */
if (bsdfIts.isLuminaire()) {
lRec = LuminaireSamplingRecord(bsdfIts, -bsdfRay.d);
lRec.value = bsdfIts.Le(-bsdfRay.d);
} else {
continue;
}
} else {
/* No intersection found. Possibly, there is a background
luminaire such as an environment map? */
if (scene->hasBackgroundLuminaire()) {
lRec.luminaire = scene->getBackgroundLuminaire();
lRec.d = -bsdfRay.d;
lRec.value = lRec.luminaire->Le(bsdfRay);
} else {
continue;
}
}
const Float lumPdf = (!(bRec.sampledType & BSDF::EDelta)) ?
scene->pdfLuminaire(its.p, lRec) : 0;
const Float weight = miWeight(bsdfPdf * fracBSDF,
lumPdf * fracLum) * weightBSDF;
Li += lRec.value * bsdfVal * weight;
}
return Li;
}
Spectrum MisPathTracer::Li(const Scene* scene, Sampler& sampler, Ray3f& ray) const
{
Spectrum L(0.f);
Intersection its;
Spectrum throughput(1.f);
bool isSpecular = true;
while (true)
{
if (!scene->rayIntersect(ray, its))
break;
if (isSpecular && its.shape->getEmitter())
{
EmitterSample emittanceSample(ray.o, its.p, its.shFrame.n);
L += throughput * its.shape->getEmitter()->eval(emittanceSample);
}
if (its.shape->getBSDF()->getType() != BSDFType::Delta)
{
EmitterSample emSam(its.p);
auto lightSpec = scene->sampleEmitter(its, sampler, emSam);
float cosFactor = its.shFrame.n.dot(emSam.wi);
if (!(cosFactor <= 0.f || lightSpec.isZero() || scene->rayIntersect(emSam.shadowRay)))
{
BSDFSample bsdfSam(its.p, its.toLocal(-ray.d), its.toLocal(emSam.wi));
bsdfSam.measure = Measure::SolidAngle;
auto bsdfSpec = its.shape->getBSDF()->eval(bsdfSam);
float pdfEm = emSam.pdf;
float pdfBsdf = its.shape->getBSDF()->pdf(bsdfSam);
L += throughput * bsdfSpec * lightSpec * cosFactor * miWeight(pdfEm, pdfBsdf);
}
}
BSDFSample bsdfSample(its.p, its.toLocal(-ray.d));
auto bsdf = its.shape->getBSDF()->sample(bsdfSample, sampler);
Intersection bsdfIts;
Ray3f bsdfRay(its.p, its.toWorld(bsdfSample.wo));
if (scene->rayIntersect(bsdfRay, bsdfIts) && bsdfIts.shape->getEmitter())
{
const auto* em = bsdfIts.shape->getEmitter();
EmitterSample emSam(its.p, bsdfIts.p, bsdfIts.shFrame.n);
emSam.wi = bsdfRay.d;
auto lightSpec = em->eval(emSam);
float pdfBsdf = its.shape->getBSDF()->pdf(bsdfSample);
float pdfEm = em->pdf(emSam) * scene->getEmitterPdf();
if (pdfBsdf + pdfEm > 0.f)
L += throughput * bsdf * lightSpec * miWeight(pdfBsdf, pdfEm);
}
isSpecular = its.shape->getBSDF()->getType() == BSDFType::Delta;
throughput *= bsdf;
ray = bsdfRay;
float q = 1.f - std::min(throughput.maxCoeff(), 0.99f);
if (sampler.next1D() > q)
throughput /= (1.f - q);
else
break;
}
return L;
}
Spectrum Li(const RayDifferential &ray, RadianceQueryRecord &rRec) const {
Spectrum LiSurf(0.0f), LiMedium(0.0f), transmittance(1.0f);
Intersection &its = rRec.its;
const Scene *scene = rRec.scene;
bool cacheQuery = (rRec.extra & RadianceQueryRecord::ECacheQuery);
bool adaptiveQuery = (rRec.extra & RadianceQueryRecord::EAdaptiveQuery);
/* Perform the first ray intersection (or ignore if the
intersection has already been provided). */
rRec.rayIntersect(ray);
if (rRec.medium) {
Ray mediumRaySegment(ray, 0, its.t);
transmittance = rRec.medium->evalTransmittance(mediumRaySegment);
mediumRaySegment.mint = ray.mint;
if (rRec.type & RadianceQueryRecord::EVolumeRadiance &&
(rRec.depth < m_maxDepth || m_maxDepth < 0) && m_bre.get() != NULL)
LiMedium = m_bre->query(mediumRaySegment, rRec.medium);
}
if (!its.isValid()) {
/* If no intersection could be found, possibly return
attenuated radiance from a background luminaire */
if ((rRec.type & RadianceQueryRecord::EEmittedRadiance) && !m_hideEmitters)
LiSurf = scene->evalEnvironment(ray);
return LiSurf * transmittance + LiMedium;
}
/* Possibly include emitted radiance if requested */
if (its.isEmitter() && (rRec.type & RadianceQueryRecord::EEmittedRadiance) && !m_hideEmitters)
LiSurf += its.Le(-ray.d);
/* Include radiance from a subsurface scattering model if requested */
if (its.hasSubsurface() && (rRec.type & RadianceQueryRecord::ESubsurfaceRadiance))
LiSurf += its.LoSub(scene, rRec.sampler, -ray.d, rRec.depth);
const BSDF *bsdf = its.getBSDF(ray);
if (rRec.depth >= m_maxDepth && m_maxDepth > 0)
return LiSurf * transmittance + LiMedium;
unsigned int bsdfType = bsdf->getType() & BSDF::EAll;
/* Irradiance cache query -> treat as diffuse */
bool isDiffuse = (bsdfType == BSDF::EDiffuseReflection) || cacheQuery;
bool hasSpecular = bsdfType & BSDF::EDelta;
/* Exhaustively recurse into all specular lobes? */
bool exhaustiveSpecular = rRec.depth < m_maxSpecularDepth && !cacheQuery;
if (isDiffuse && (dot(its.shFrame.n, ray.d) < 0 || (bsdf->getType() & BSDF::EBackSide))) {
/* 1. Diffuse indirect */
int maxDepth = m_maxDepth == -1 ? INT_MAX : (m_maxDepth-rRec.depth);
if (rRec.type & RadianceQueryRecord::EIndirectSurfaceRadiance && m_globalPhotonMap.get())
LiSurf += m_globalPhotonMap->estimateIrradiance(its.p,
its.shFrame.n, m_globalLookupRadius, maxDepth,
m_globalLookupSize) * bsdf->getDiffuseReflectance(its) * INV_PI;
if (rRec.type & RadianceQueryRecord::ECausticRadiance && m_causticPhotonMap.get())
LiSurf += m_causticPhotonMap->estimateIrradiance(its.p,
its.shFrame.n, m_causticLookupRadius, maxDepth,
m_causticLookupSize) * bsdf->getDiffuseReflectance(its) * INV_PI;
}
if (hasSpecular && exhaustiveSpecular
&& (rRec.type & RadianceQueryRecord::EIndirectSurfaceRadiance)) {
/* 1. Specular indirect */
int compCount = bsdf->getComponentCount();
RadianceQueryRecord rRec2;
for (int i=0; i<compCount; i++) {
unsigned int type = bsdf->getType(i);
if (!(type & BSDF::EDelta))
continue;
/* Sample the BSDF and recurse */
BSDFSamplingRecord bRec(its, rRec.sampler, ERadiance);
bRec.component = i;
Spectrum bsdfVal = bsdf->sample(bRec, Point2(0.5f));
if (bsdfVal.isZero())
continue;
rRec2.recursiveQuery(rRec, RadianceQueryRecord::ERadiance);
RayDifferential bsdfRay(its.p, its.toWorld(bRec.wo), ray.time);
if (its.isMediumTransition())
rRec2.medium = its.getTargetMedium(bsdfRay.d);
LiSurf += bsdfVal * m_parentIntegrator->Li(bsdfRay, rRec2);
}
}
/* Estimate the direct illumination if this is requested */
int numEmitterSamples = m_directSamples, numBSDFSamples;
Float weightLum, weightBSDF;
Point2 *sampleArray;
Point2 sample;
if (rRec.depth > 1 || cacheQuery || adaptiveQuery) {
/* This integrator is used recursively by another integrator.
Be less accurate as this sample will not directly be observed. */
numBSDFSamples = numEmitterSamples = 1;
weightLum = weightBSDF = 1.0f;
} else {
if (isDiffuse) {
numBSDFSamples = m_directSamples;
weightBSDF = weightLum = m_invEmitterSamples;
} else {
numBSDFSamples = m_glossySamples;
weightLum = m_invEmitterSamples;
weightBSDF = m_invGlossySamples;
}
}
if ((bsdfType & BSDF::ESmooth) && (rRec.type & RadianceQueryRecord::EDirectSurfaceRadiance)) {
DirectSamplingRecord dRec(its);
if (numEmitterSamples > 1) {
sampleArray = rRec.sampler->next2DArray(m_directSamples);
} else {
sample = rRec.nextSample2D(); sampleArray = &sample;
}
for (int i=0; i<numEmitterSamples; ++i) {
int interactions = m_maxDepth - rRec.depth - 1;
Spectrum value = scene->sampleAttenuatedEmitterDirect(
dRec, its, rRec.medium, interactions,
sampleArray[i], rRec.sampler);
/* Estimate the direct illumination if this is requested */
if (!value.isZero()) {
const Emitter *emitter = static_cast<const Emitter *>(dRec.object);
/* Allocate a record for querying the BSDF */
BSDFSamplingRecord bRec(its, its.toLocal(dRec.d));
/* Evaluate BSDF * cos(theta) */
const Spectrum bsdfVal = bsdf->eval(bRec);
if (!bsdfVal.isZero()) {
/* Calculate prob. of having sampled that direction
using BSDF sampling */
if (!hasSpecular || exhaustiveSpecular)
bRec.typeMask = BSDF::ESmooth;
Float bsdfPdf = (emitter->isOnSurface()
&& dRec.measure == ESolidAngle
&& interactions == 0)
? bsdf->pdf(bRec) : (Float) 0.0f;
/* Weight using the power heuristic */
const Float weight = miWeight(dRec.pdf * numEmitterSamples,
bsdfPdf * numBSDFSamples) * weightLum;
LiSurf += value * bsdfVal * weight;
}
}
}
}
/* ==================================================================== */
/* BSDF sampling */
/* ==================================================================== */
/* Sample direct compontent via BSDF sampling if this is generally requested AND
the BSDF is smooth, or there is a delta component that was not handled by the
exhaustive sampling loop above */
bool bsdfSampleDirect = (rRec.type & RadianceQueryRecord::EDirectSurfaceRadiance) &&
((bsdfType & BSDF::ESmooth) || (hasSpecular && !exhaustiveSpecular));
/* Sample indirect component via BSDF sampling if this is generally requested AND
the BSDF is non-diffuse (diffuse is handled by the global photon map)
or there is a delta component that was not handled by the exhaustive sampling loop
above. */
bool bsdfSampleIndirect = (rRec.type & RadianceQueryRecord::EIndirectSurfaceRadiance) &&
!isDiffuse && ((bsdfType & BSDF::ESmooth) || (hasSpecular && !exhaustiveSpecular));
if (bsdfSampleDirect || bsdfSampleIndirect) {
if (numBSDFSamples > 1) {
sampleArray = rRec.sampler->next2DArray(
std::max(m_directSamples, m_glossySamples));
} else {
sample = rRec.nextSample2D(); sampleArray = &sample;
}
RadianceQueryRecord rRec2;
Intersection &bsdfIts = rRec2.its;
DirectSamplingRecord dRec(its);
for (int i=0; i<numBSDFSamples; ++i) {
/* Sample BSDF * cos(theta) */
BSDFSamplingRecord bRec(its, rRec.sampler, ERadiance);
if (!hasSpecular || exhaustiveSpecular)
bRec.typeMask = BSDF::ESmooth;
Float bsdfPdf;
Spectrum bsdfVal = bsdf->sample(bRec, bsdfPdf, sampleArray[i]);
if (bsdfVal.isZero())
continue;
/* Trace a ray in this direction */
RayDifferential bsdfRay(its.p, its.toWorld(bRec.wo), ray.time);
Spectrum value;
bool hitEmitter = false;
if (scene->rayIntersect(bsdfRay, bsdfIts)) {
/* Intersected something - check if it was a luminaire */
if (bsdfIts.isEmitter() && bsdfSampleDirect) {
value = bsdfIts.Le(-bsdfRay.d);
dRec.setQuery(bsdfRay, bsdfIts);
hitEmitter = true;
}
} else if (bsdfSampleDirect) {
/* Intersected nothing -- perhaps there is an environment map? */
const Emitter *env = scene->getEnvironmentEmitter();
if (env) {
value = env->evalEnvironment(bsdfRay);
if (env->fillDirectSamplingRecord(dRec, bsdfRay))
hitEmitter = true;
}
}
if (hitEmitter) {
const Float emitterPdf = scene->pdfEmitterDirect(dRec);
Spectrum transmittance = rRec2.medium ?
rRec2.medium->evalTransmittance(Ray(bsdfRay, 0, bsdfIts.t)) : Spectrum(1.0f);
const Float weight = miWeight(bsdfPdf * numBSDFSamples,
emitterPdf * numEmitterSamples) * weightBSDF;
LiSurf += value * bsdfVal * weight * transmittance;
}
/* Recurse */
if (bsdfSampleIndirect) {
rRec2.recursiveQuery(rRec,
RadianceQueryRecord::ERadianceNoEmission);
rRec2.type ^= RadianceQueryRecord::EIntersection;
if (its.isMediumTransition())
rRec2.medium = its.getTargetMedium(bsdfRay.d);
LiSurf += bsdfVal * m_parentIntegrator->Li(bsdfRay, rRec2) * weightBSDF;
}
}
}
return LiSurf * transmittance + LiMedium;
}
