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;
}
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
}
