Spectrum DiffusePRTIntegrator::Li(const Scene *scene, const Renderer *,
const RayDifferential &ray, const Intersection &isect,
const Sample *sample, MemoryArena &arena) const {
Spectrum L = 0.f;
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;
// Compute reflected radiance using diffuse PRT
// Project diffuse transfer function at point to SH
Spectrum *c_transfer = arena.Alloc<Spectrum>(SHTerms(lmax));
SHComputeDiffuseTransfer(p, Faceforward(n, wo), isect.rayEpsilon,
scene, *sample->rng, nSamples, lmax, c_transfer);
// Compute integral of product of incident radiance and transfer function
Spectrum LT = 0.f;
for (int i = 0; i < SHTerms(lmax); ++i)
LT += c_in[i] * c_transfer[i];
// Compute reflectance at point for diffuse transfer
const int sqrtRhoSamples = 6;
float rhoRSamples[2*sqrtRhoSamples*sqrtRhoSamples];
StratifiedSample2D(rhoRSamples, sqrtRhoSamples, sqrtRhoSamples, *sample->rng);
Spectrum Kd = bsdf->rho(wo, sqrtRhoSamples*sqrtRhoSamples, rhoRSamples,
BSDF_ALL_REFLECTION) * INV_PI;
return L + Kd * LT.Clamp();
}
Spectrum UseRadianceProbes::Li(const Scene *scene, const Renderer *renderer,
const RayDifferential &ray, const Intersection &isect,
const Sample *sample, RNG &rng, MemoryArena &arena, int wavelength) 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, wavelength);
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
// Compute reflection for radiance probes integrator
if (!includeDirectInProbes)
L += UniformSampleAllLights(scene, renderer, arena, p, n,
wo, isect.rayEpsilon, ray.time, bsdf, sample, rng,
lightSampleOffsets, bsdfSampleOffsets);
// Compute reflected lighting using radiance probes
// Compute probe coordinates and offsets for lookup point
Vector offset = bbox.Offset(p);
float voxx = (offset.x * nProbes[0]) - 0.5f;
float voxy = (offset.y * nProbes[1]) - 0.5f;
float voxz = (offset.z * nProbes[2]) - 0.5f;
int vx = Floor2Int(voxx), vy = Floor2Int(voxy), vz = Floor2Int(voxz);
float dx = voxx - vx, dy = voxy - vy, dz = voxz - vz;
// Get radiance probe coefficients around lookup point
const Spectrum *b000 = c_inXYZ(lmax, vx, vy, vz);
const Spectrum *b100 = c_inXYZ(lmax, vx+1, vy, vz);
const Spectrum *b010 = c_inXYZ(lmax, vx, vy+1, vz);
const Spectrum *b110 = c_inXYZ(lmax, vx+1, vy+1, vz);
const Spectrum *b001 = c_inXYZ(lmax, vx, vy, vz+1);
const Spectrum *b101 = c_inXYZ(lmax, vx+1, vy, vz+1);
const Spectrum *b011 = c_inXYZ(lmax, vx, vy+1, vz+1);
const Spectrum *b111 = c_inXYZ(lmax, vx+1, vy+1, vz+1);
// Compute incident radiance from radiance probe coefficients
Spectrum *c_inp = arena.Alloc<Spectrum>(SHTerms(lmax));
for (int i = 0; i < SHTerms(lmax); ++i) {
// Do trilinear interpolation to compute SH coefficients at point
Spectrum c00 = Lerp(dx, b000[i], b100[i]);
Spectrum c10 = Lerp(dx, b010[i], b110[i]);
Spectrum c01 = Lerp(dx, b001[i], b101[i]);
Spectrum c11 = Lerp(dx, b011[i], b111[i]);
Spectrum c0 = Lerp(dy, c00, c10);
Spectrum c1 = Lerp(dy, c01, c11);
c_inp[i] = Lerp(dz, c0, c1);
}
// Convolve incident radiance to compute irradiance function
Spectrum *c_E = arena.Alloc<Spectrum>(SHTerms(lmax));
SHConvolveCosTheta(lmax, c_inp, c_E);
// Evaluate irradiance function and accumulate reflection
Spectrum rho = bsdf->rho(wo, rng, BSDF_ALL_REFLECTION);
float *Ylm = ALLOCA(float, SHTerms(lmax));
SHEvaluate(Vector(Faceforward(n, wo)), lmax, Ylm);
Spectrum E = 0.f;
for (int i = 0; i < SHTerms(lmax); ++i)
E += c_E[i] * Ylm[i];
L += rho * INV_PI * E.Clamp();
return L;
}
void IGIIntegrator::Preprocess(const Scene *scene, const Camera *camera,
const Renderer *renderer) {
if (scene->lights.size() == 0) return;
MemoryArena arena;
RNG rng;
// Compute samples for emitted rays from lights
vector<float> lightNum(nLightPaths * nLightSets);
vector<float> lightSampPos(2 * nLightPaths * nLightSets, 0.f);
vector<float> lightSampComp(nLightPaths * nLightSets, 0.f);
vector<float> lightSampDir(2 * nLightPaths * nLightSets, 0.f);
LDShuffleScrambled1D(nLightPaths, nLightSets, &lightNum[0], rng);
LDShuffleScrambled2D(nLightPaths, nLightSets, &lightSampPos[0], rng);
LDShuffleScrambled1D(nLightPaths, nLightSets, &lightSampComp[0], rng);
LDShuffleScrambled2D(nLightPaths, nLightSets, &lightSampDir[0], rng);
// Precompute information for light sampling densities
Distribution1D *lightDistribution = ComputeLightSamplingCDF(scene);
for (uint32_t s = 0; s < nLightSets; ++s) {
for (uint32_t i = 0; i < nLightPaths; ++i) {
// Follow path _i_ from light to create virtual lights
int sampOffset = s*nLightPaths + i;
// Choose light source to trace virtual light path from
float lightPdf;
int ln = lightDistribution->SampleDiscrete(lightNum[sampOffset],
&lightPdf);
Light *light = scene->lights[ln];
// Sample ray leaving light source for virtual light path
RayDifferential ray;
float pdf;
LightSample ls(lightSampPos[2*sampOffset], lightSampPos[2*sampOffset+1],
lightSampComp[sampOffset]);
Normal Nl;
Spectrum alpha = light->Sample_L(scene, ls, lightSampDir[2*sampOffset],
lightSampDir[2*sampOffset+1],
camera->shutterOpen, &ray, &Nl, &pdf);
if (pdf == 0.f || alpha.IsBlack()) continue;
alpha /= pdf * lightPdf;
Intersection isect;
while (scene->Intersect(ray, &isect) && !alpha.IsBlack()) {
// Create virtual light and sample new ray for path
alpha *= renderer->Transmittance(scene, RayDifferential(ray), NULL,
rng, arena);
Vector wo = -ray.d;
BSDF *bsdf = isect.GetBSDF(ray, arena);
// Create virtual light at ray intersection point
Spectrum contrib = alpha * bsdf->rho(wo, rng) / M_PI;
virtualLights[s].push_back(VirtualLight(isect.dg.p, isect.dg.nn, contrib,
isect.rayEpsilon));
// Sample new ray direction and update weight for virtual light path
Vector wi;
float pdf;
BSDFSample bsdfSample(rng);
Spectrum fr = bsdf->Sample_f(wo, &wi, bsdfSample, &pdf);
if (fr.IsBlack() || pdf == 0.f)
break;
Spectrum contribScale = fr * AbsDot(wi, bsdf->dgShading.nn) / pdf;
// Possibly terminate virtual light path with Russian roulette
float rrProb = min(1.f, contribScale.y());
if (rng.RandomFloat() > rrProb)
break;
alpha *= contribScale / rrProb;
ray = RayDifferential(isect.dg.p, wi, ray, isect.rayEpsilon);
}
arena.FreeAll();
}
}
delete lightDistribution;
}
Spectrum IrradianceCache::IndirectLo(const Point &p,
const Normal &n, const Vector &wo, BSDF *bsdf,
BxDFType flags, const Sample *sample,
const Scene *scene) const {
if (bsdf->NumComponents(flags) == 0)
return Spectrum(0.);
Spectrum E;
if (!InterpolateIrradiance(scene, p, n, &E)) {
// Compute irradiance at current point
u_int scramble[2] = { RandomUInt(), RandomUInt() };
float sumInvDists = 0.;
for (int i = 0; i < nSamples; ++i) {
// Trace ray to sample radiance for irradiance estimate
// Update irradiance statistics for rays traced
static StatsCounter nIrradiancePaths("Irradiance Cache",
"Paths followed for irradiance estimates");
++nIrradiancePaths;
float u[2];
Sample02(i, scramble, u);
Vector w = CosineSampleHemisphere(u[0], u[1]);
RayDifferential r(p, bsdf->LocalToWorld(w));
if (Dot(r.d, n) < 0) r.d = -r.d;
Spectrum L(0.);
// Do path tracing to compute radiance along ray for estimate
{
// Declare common path integration variables
Spectrum pathThroughput = 1.;
RayDifferential ray(r);
bool specularBounce = false;
for (int pathLength = 0; ; ++pathLength) {
// Find next vertex of path
Intersection isect;
if (!scene->Intersect(ray, &isect))
break;
if (pathLength == 0)
r.maxt = ray.maxt;
pathThroughput *= scene->Transmittance(ray);
// Possibly add emitted light at path vertex
if (specularBounce)
L += pathThroughput * isect.Le(-ray.d);
// Evaluate BSDF at hit point
BSDF *bsdf = isect.GetBSDF(ray);
// Sample illumination from lights to find path contribution
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
Vector wo = -ray.d;
L += pathThroughput *
UniformSampleOneLight(scene, p, n, wo, bsdf, sample);
if (pathLength+1 == maxIndirectDepth) break;
// Sample BSDF to get new path direction
// Get random numbers for sampling new direction, \mono{bs1}, \mono{bs2}, and \mono{bcs}
float bs1 = RandomFloat(), bs2 = RandomFloat(), bcs = RandomFloat();
Vector wi;
float pdf;
BxDFType flags;
Spectrum f = bsdf->Sample_f(wo, &wi, bs1, bs2, bcs,
&pdf, BSDF_ALL, &flags);
if (f.Black() || pdf == 0.)
break;
specularBounce = (flags & BSDF_SPECULAR) != 0;
pathThroughput *= f * AbsDot(wi, n) / pdf;
ray = RayDifferential(p, wi);
// Possibly terminate the path
if (pathLength > 3) {
float continueProbability = .5f;
if (RandomFloat() > continueProbability)
break;
pathThroughput /= continueProbability;
}
}
}
E += L;
float dist = r.maxt * r.d.Length();
sumInvDists += 1.f / dist;
}
E *= M_PI / float(nSamples);
// Add computed irradiance value to cache
// Update statistics for new irradiance sample
static StatsCounter nSamplesComputed("Irradiance Cache",
"Irradiance estimates computed");
++nSamplesComputed;
// Compute bounding box of irradiance sample's contribution region
static float minMaxDist =
.001f * powf(scene->WorldBound().Volume(), 1.f/3.f);
static float maxMaxDist =
.125f * powf(scene->WorldBound().Volume(), 1.f/3.f);
float maxDist = nSamples / sumInvDists;
if (minMaxDist > 0.f)
maxDist = Clamp(maxDist, minMaxDist, maxMaxDist);
maxDist *= maxError;
BBox sampleExtent(p);
sampleExtent.Expand(maxDist);
octree->Add(IrradianceSample(E, p, n, maxDist),
sampleExtent);
}
return .5f * bsdf->rho(wo, flags) * E;
}
void PhotonShootingTask::Run() {
// Declare local variables for _PhotonShootingTask_
MemoryArena arena;
RNG rng(31 * taskNum);
vector<Photon> localDirectPhotons, localIndirectPhotons, localCausticPhotons;
vector<RadiancePhoton> localRadiancePhotons;
uint32_t totalPaths = 0;
bool causticDone = (integrator->nCausticPhotonsWanted == 0);
bool indirectDone = (integrator->nIndirectPhotonsWanted == 0);
PermutedHalton halton(6, rng);
vector<Spectrum> localRpReflectances, localRpTransmittances;
while (true) {
// Follow photon paths for a block of samples
const uint32_t blockSize = 4096;
for (uint32_t i = 0; i < blockSize; ++i) {
float u[6];
halton.Sample(++totalPaths, u);
// Choose light to shoot photon from
float lightPdf;
int lightNum = lightDistribution->SampleDiscrete(u[0], &lightPdf);
const Light *light = scene->lights[lightNum];
// Generate _photonRay_ from light source and initialize _alpha_
RayDifferential photonRay;
float pdf;
LightSample ls(u[1], u[2], u[3]);
Normal Nl;
Spectrum Le = light->Sample_L(scene, ls, u[4], u[5],
time, &photonRay, &Nl, &pdf);
if (pdf == 0.f || Le.IsBlack()) continue;
Spectrum alpha = (AbsDot(Nl, photonRay.d) * Le) / (pdf * lightPdf);
if (!alpha.IsBlack()) {
// Follow photon path through scene and record intersections
PBRT_PHOTON_MAP_STARTED_RAY_PATH(&photonRay, &alpha);
bool specularPath = true;
Intersection photonIsect;
int nIntersections = 0;
while (scene->Intersect(photonRay, &photonIsect)) {
++nIntersections;
// Handle photon/surface intersection
alpha *= renderer->Transmittance(scene, photonRay, NULL, rng, arena);
BSDF *photonBSDF = photonIsect.GetBSDF(photonRay, arena);
BxDFType specularType = BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_SPECULAR);
bool hasNonSpecular = (photonBSDF->NumComponents() >
photonBSDF->NumComponents(specularType));
Vector wo = -photonRay.d;
if (hasNonSpecular) {
// Deposit photon at surface
Photon photon(photonIsect.dg.p, alpha, wo);
bool depositedPhoton = false;
if (specularPath && nIntersections > 1) {
if (!causticDone) {
PBRT_PHOTON_MAP_DEPOSITED_CAUSTIC_PHOTON(&photonIsect.dg, &alpha, &wo);
depositedPhoton = true;
localCausticPhotons.push_back(photon);
}
}
else {
// Deposit either direct or indirect photon
// stop depositing direct photons once indirectDone is true; don't
// want to waste memory storing too many if we're going a long time
// trying to get enough caustic photons desposited.
if (nIntersections == 1 && !indirectDone && integrator->finalGather) {
PBRT_PHOTON_MAP_DEPOSITED_DIRECT_PHOTON(&photonIsect.dg, &alpha, &wo);
depositedPhoton = true;
localDirectPhotons.push_back(photon);
}
else if (nIntersections > 1 && !indirectDone) {
PBRT_PHOTON_MAP_DEPOSITED_INDIRECT_PHOTON(&photonIsect.dg, &alpha, &wo);
depositedPhoton = true;
localIndirectPhotons.push_back(photon);
}
}
// Possibly create radiance photon at photon intersection point
if (depositedPhoton && integrator->finalGather &&
rng.RandomFloat() < .125f) {
Normal n = photonIsect.dg.nn;
n = Faceforward(n, -photonRay.d);
localRadiancePhotons.push_back(RadiancePhoton(photonIsect.dg.p, n));
Spectrum rho_r = photonBSDF->rho(rng, BSDF_ALL_REFLECTION);
localRpReflectances.push_back(rho_r);
Spectrum rho_t = photonBSDF->rho(rng, BSDF_ALL_TRANSMISSION);
localRpTransmittances.push_back(rho_t);
}
}
if (nIntersections >= integrator->maxPhotonDepth) break;
// Sample new photon ray direction
Vector wi;
float pdf;
BxDFType flags;
Spectrum fr = photonBSDF->Sample_f(wo, &wi, BSDFSample(rng),
&pdf, BSDF_ALL, &flags);
if (fr.IsBlack() || pdf == 0.f) break;
Spectrum anew = alpha * fr *
AbsDot(wi, photonBSDF->dgShading.nn) / pdf;
// Possibly terminate photon path with Russian roulette
float continueProb = min(1.f, anew.y() / alpha.y());
if (rng.RandomFloat() > continueProb)
break;
alpha = anew / continueProb;
specularPath &= ((flags & BSDF_SPECULAR) != 0);
if (indirectDone && !specularPath) break;
photonRay = RayDifferential(photonIsect.dg.p, wi, photonRay,
photonIsect.rayEpsilon);
}
PBRT_PHOTON_MAP_FINISHED_RAY_PATH(&photonRay, &alpha);
}
arena.FreeAll();
}
// Merge local photon data with data in _PhotonIntegrator_
{ MutexLock lock(mutex);
// Give up if we're not storing enough photons
if (abortTasks)
return;
if (nshot > 500000 &&
(unsuccessful(integrator->nCausticPhotonsWanted,
causticPhotons.size(), blockSize) ||
unsuccessful(integrator->nIndirectPhotonsWanted,
indirectPhotons.size(), blockSize))) {
Error("Unable to store enough photons. Giving up.\n");
causticPhotons.erase(causticPhotons.begin(), causticPhotons.end());
indirectPhotons.erase(indirectPhotons.begin(), indirectPhotons.end());
radiancePhotons.erase(radiancePhotons.begin(), radiancePhotons.end());
abortTasks = true;
return;
}
progress.Update(localIndirectPhotons.size() + localCausticPhotons.size());
nshot += blockSize;
// Merge indirect photons into shared array
if (!indirectDone) {
integrator->nIndirectPaths += blockSize;
for (uint32_t i = 0; i < localIndirectPhotons.size(); ++i)
indirectPhotons.push_back(localIndirectPhotons[i]);
localIndirectPhotons.erase(localIndirectPhotons.begin(),
localIndirectPhotons.end());
if (indirectPhotons.size() >= integrator->nIndirectPhotonsWanted)
indirectDone = true;
nDirectPaths += blockSize;
for (uint32_t i = 0; i < localDirectPhotons.size(); ++i)
directPhotons.push_back(localDirectPhotons[i]);
localDirectPhotons.erase(localDirectPhotons.begin(),
localDirectPhotons.end());
}
// Merge direct, caustic, and radiance photons into shared array
if (!causticDone) {
integrator->nCausticPaths += blockSize;
for (uint32_t i = 0; i < localCausticPhotons.size(); ++i)
causticPhotons.push_back(localCausticPhotons[i]);
localCausticPhotons.erase(localCausticPhotons.begin(), localCausticPhotons.end());
if (causticPhotons.size() >= integrator->nCausticPhotonsWanted)
causticDone = true;
}
for (uint32_t i = 0; i < localRadiancePhotons.size(); ++i)
radiancePhotons.push_back(localRadiancePhotons[i]);
localRadiancePhotons.erase(localRadiancePhotons.begin(), localRadiancePhotons.end());
for (uint32_t i = 0; i < localRpReflectances.size(); ++i)
rpReflectances.push_back(localRpReflectances[i]);
localRpReflectances.erase(localRpReflectances.begin(), localRpReflectances.end());
for (uint32_t i = 0; i < localRpTransmittances.size(); ++i)
rpTransmittances.push_back(localRpTransmittances[i]);
localRpTransmittances.erase(localRpTransmittances.begin(), localRpTransmittances.end());
}
// Exit task if enough photons have been found
if (indirectDone && causticDone)
break;
}
}
void ExPhotonIntegrator::Preprocess(const Scene *scene) {
if (scene->lights.size() == 0) return;
ProgressReporter progress(nCausticPhotons+ // NOBOOK
nIndirectPhotons, "Shooting photons"); // NOBOOK
vector<Photon> causticPhotons;
vector<Photon> indirectPhotons;
vector<Photon> directPhotons;
vector<RadiancePhoton> radiancePhotons;
causticPhotons.reserve(nCausticPhotons); // NOBOOK
indirectPhotons.reserve(nIndirectPhotons); // NOBOOK
// Initialize photon shooting statistics
static StatsCounter nshot("Photon Map",
"Number of photons shot from lights");
bool causticDone = (nCausticPhotons == 0);
bool indirectDone = (nIndirectPhotons == 0);
// Compute light power CDF for photon shooting
int nLights = int(scene->lights.size());
float *lightPower = (float *)alloca(nLights * sizeof(float));
float *lightCDF = (float *)alloca((nLights+1) * sizeof(float));
for (int i = 0; i < nLights; ++i)
lightPower[i] = scene->lights[i]->Power(scene).y();
float totalPower;
ComputeStep1dCDF(lightPower, nLights, &totalPower, lightCDF);
// Declare radiance photon reflectance arrays
vector<Spectrum> rpReflectances, rpTransmittances;
while (!causticDone || !indirectDone) {
++nshot;
// Give up if we're not storing enough photons
if (nshot > 500000 &&
(unsuccessful(nCausticPhotons,
causticPhotons.size(),
nshot) ||
unsuccessful(nIndirectPhotons,
indirectPhotons.size(),
nshot))) {
Error("Unable to store enough photons. Giving up.\n");
return;
}
// Trace a photon path and store contribution
// Choose 4D sample values for photon
float u[4];
u[0] = RadicalInverse((int)nshot+1, 2);
u[1] = RadicalInverse((int)nshot+1, 3);
u[2] = RadicalInverse((int)nshot+1, 5);
u[3] = RadicalInverse((int)nshot+1, 7);
// Choose light to shoot photon from
float lightPdf;
float uln = RadicalInverse((int)nshot+1, 11);
int lightNum = Floor2Int(SampleStep1d(lightPower, lightCDF,
totalPower, nLights, uln, &lightPdf) * nLights);
lightNum = min(lightNum, nLights-1);
const Light *light = scene->lights[lightNum];
// Generate _photonRay_ from light source and initialize _alpha_
RayDifferential photonRay;
float pdf;
Spectrum alpha = light->Sample_L(scene, u[0], u[1], u[2], u[3],
&photonRay, &pdf);
if (pdf == 0.f || alpha.Black()) continue;
alpha /= pdf * lightPdf;
if (!alpha.Black()) {
// Follow photon path through scene and record intersections
bool specularPath = false;
Intersection photonIsect;
int nIntersections = 0;
while (scene->Intersect(photonRay, &photonIsect)) {
++nIntersections;
// Handle photon/surface intersection
alpha *= scene->Transmittance(photonRay);
Vector wo = -photonRay.d;
BSDF *photonBSDF = photonIsect.GetBSDF(photonRay);
BxDFType specularType = BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_SPECULAR);
bool hasNonSpecular = (photonBSDF->NumComponents() >
photonBSDF->NumComponents(specularType));
if (hasNonSpecular) {
// Deposit photon at surface
Photon photon(photonIsect.dg.p, alpha, wo);
if (nIntersections == 1) {
// Deposit direct photon
directPhotons.push_back(photon);
}
else {
// Deposit either caustic or indirect photon
if (specularPath) {
// Process caustic photon intersection
if (!causticDone) {
causticPhotons.push_back(photon);
if (causticPhotons.size() == nCausticPhotons) {
causticDone = true;
nCausticPaths = (int)nshot;
causticMap = new KdTree<Photon, PhotonProcess>(causticPhotons);
}
progress.Update();
}
}
else {
// Process indirect lighting photon intersection
if (!indirectDone) {
indirectPhotons.push_back(photon);
if (indirectPhotons.size() == nIndirectPhotons) {
indirectDone = true;
nIndirectPaths = (int)nshot;
indirectMap = new KdTree<Photon, PhotonProcess>(indirectPhotons);
}
progress.Update();
}
}
}
if (finalGather && RandomFloat() < .125f) {
// Store data for radiance photon
static StatsCounter rp("Photon Map", "Radiance photons created"); // NOBOOK
++rp; // NOBOOK
Normal n = photonIsect.dg.nn;
if (Dot(n, photonRay.d) > 0.f) n = -n;
radiancePhotons.push_back(RadiancePhoton(photonIsect.dg.p, n));
Spectrum rho_r = photonBSDF->rho(BSDF_ALL_REFLECTION);
rpReflectances.push_back(rho_r);
Spectrum rho_t = photonBSDF->rho(BSDF_ALL_TRANSMISSION);
rpTransmittances.push_back(rho_t);
}
}
// Sample new photon ray direction
Vector wi;
float pdf;
BxDFType flags;
// Get random numbers for sampling outgoing photon direction
float u1, u2, u3;
if (nIntersections == 1) {
u1 = RadicalInverse((int)nshot+1, 13);
u2 = RadicalInverse((int)nshot+1, 17);
u3 = RadicalInverse((int)nshot+1, 19);
}
else {
u1 = RandomFloat();
u2 = RandomFloat();
u3 = RandomFloat();
}
// Compute new photon weight and possibly terminate with RR
Spectrum fr = photonBSDF->Sample_f(wo, &wi, u1, u2, u3,
&pdf, BSDF_ALL, &flags);
if (fr.Black() || pdf == 0.f)
break;
Spectrum anew = alpha * fr *
AbsDot(wi, photonBSDF->dgShading.nn) / pdf;
float continueProb = min(1.f, anew.y() / alpha.y());
if (RandomFloat() > continueProb || nIntersections > 10)
break;
alpha = anew / continueProb;
specularPath = (nIntersections == 1 || specularPath) &&
((flags & BSDF_SPECULAR) != 0);
photonRay = RayDifferential(photonIsect.dg.p, wi);
}
}
BSDF::FreeAll();
}
progress.Done(); // NOBOOK
// Precompute radiance at a subset of the photons
KdTree<Photon, PhotonProcess> directMap(directPhotons);
int nDirectPaths = nshot;
if (finalGather) {
ProgressReporter p2(radiancePhotons.size(), "Computing photon radiances"); // NOBOOK
for (u_int i = 0; i < radiancePhotons.size(); ++i) {
// Compute radiance for radiance photon _i_
RadiancePhoton &rp = radiancePhotons[i];
const Spectrum &rho_r = rpReflectances[i];
const Spectrum &rho_t = rpTransmittances[i];
Spectrum E;
Point p = rp.p;
Normal n = rp.n;
if (!rho_r.Black()) {
E = estimateE(&directMap, nDirectPaths, p, n) +
estimateE(indirectMap, nIndirectPaths, p, n) +
estimateE(causticMap, nCausticPaths, p, n);
rp.Lo += E * INV_PI * rho_r;
}
if (!rho_t.Black()) {
E = estimateE(&directMap, nDirectPaths, p, -n) +
estimateE(indirectMap, nIndirectPaths, p, -n) +
estimateE(causticMap, nCausticPaths, p, -n);
rp.Lo += E * INV_PI * rho_t;
}
p2.Update(); // NOBOOK
}
radianceMap = new KdTree<RadiancePhoton,
RadiancePhotonProcess>(radiancePhotons);
p2.Done(); // NOBOOK
}
}
void IGIIntegrator::Preprocess(const Scene *scene) {
if (scene->lights.size() == 0) return;
// Compute samples for emitted rays from lights
float *lightNum = new float[nLightPaths * nLightSets];
float *lightSamp0 = new float[2 * nLightPaths * nLightSets];
float *lightSamp1 = new float[2 * nLightPaths * nLightSets];
LDShuffleScrambled1D(nLightPaths, nLightSets, lightNum);
LDShuffleScrambled2D(nLightPaths, nLightSets, lightSamp0);
LDShuffleScrambled2D(nLightPaths, nLightSets, lightSamp1);
// Precompute information for light sampling densities
int nLights = int(scene->lights.size());
float *lightPower = (float *)alloca(nLights * sizeof(float));
float *lightCDF = (float *)alloca((nLights+1) * sizeof(float));
for (int i = 0; i < nLights; ++i)
lightPower[i] = scene->lights[i]->Power(scene).y();
float totalPower;
ComputeStep1dCDF(lightPower, nLights, &totalPower, lightCDF);
for (u_int s = 0; s < nLightSets; ++s) {
for (u_int i = 0; i < nLightPaths; ++i) {
// Follow path _i_ from light to create virtual lights
int sampOffset = s*nLightPaths + i;
// Choose light source to trace path from
float lightPdf;
int lNum = Floor2Int(SampleStep1d(lightPower, lightCDF,
totalPower, nLights, lightNum[sampOffset], &lightPdf) * nLights);
// fprintf(stderr, "samp %f -> num %d\n", lightNum[sampOffset], lNum);
Light *light = scene->lights[lNum];
// Sample ray leaving light source
RayDifferential ray;
float pdf;
Spectrum alpha =
light->Sample_L(scene, lightSamp0[2*sampOffset],
lightSamp0[2*sampOffset+1],
lightSamp1[2*sampOffset],
lightSamp1[2*sampOffset+1],
&ray, &pdf);
if (pdf == 0.f || alpha.Black()) continue;
alpha /= pdf * lightPdf;
// fprintf(stderr, "initial alpha %f, light # %d\n", alpha.y(), lNum);
Intersection isect;
int nIntersections = 0;
while (scene->Intersect(ray, &isect) && !alpha.Black()) {
++nIntersections;
alpha *= scene->Transmittance(ray);
Vector wo = -ray.d;
BSDF *bsdf = isect.GetBSDF(ray);
// Create virtual light at ray intersection point
static StatsCounter vls("IGI Integrator", "Virtual Lights Created"); //NOBOOK
++vls; //NOBOOK
Spectrum Le = alpha * bsdf->rho(wo) / M_PI;
// fprintf(stderr, "\tmade light with le y %f\n", Le.y());
virtualLights[s].push_back(VirtualLight(isect.dg.p, isect.dg.nn, Le));
// Sample new ray direction and update weight
Vector wi;
float pdf;
BxDFType flags;
Spectrum fr = bsdf->Sample_f(wo, &wi, RandomFloat(),
RandomFloat(), RandomFloat(),
&pdf, BSDF_ALL, &flags);
if (fr.Black() || pdf == 0.f)
break;
Spectrum anew = alpha * fr * AbsDot(wi, bsdf->dgShading.nn) / pdf;
float r = anew.y() / alpha.y();
// fprintf(stderr, "\tr = %f\n", r);
if (RandomFloat() > r)
break;
alpha = anew / r;
// fprintf(stderr, "\tnew alpha %f\n", alpha.y());
ray = RayDifferential(isect.dg.p, wi);
}
BSDF::FreeAll();
}
}
delete[] lightNum; // NOBOOK
delete[] lightSamp0; // NOBOOK
delete[] lightSamp1; // NOBOOK
}
