void Raytracer::forwardTrace(Photon* photon, const int bouncesLeft, const int numberOfPhotons)
{
if (bouncesLeft > 0)
{
Tri::Intersector intersector;
float distance = inf();
Ray photonRay(photon->position, photon->direction);
if (_triTree.intersectRay(photonRay, intersector, distance))
{
Color3 pixelColor;
Vector3 position, normal;
Vector2 texCoord;
intersector.getResult(position, normal, texCoord);
photon->position = position + normal * 0.0001f;
Photon* photonCopy = new Photon(photon);
//if (bouncesLeft != _settings._forwardBounces)
{
_photonMap->insert(photon);
}
SurfaceSample surfaceSample(intersector);
if (scatter(intersector, photonCopy))
{
forwardTrace(photonCopy, bouncesLeft - 1, numberOfPhotons);
}
}
}
}
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_
LightSample ls(u[1], u[2], u[3]);
LightInfo2 li = light->Sample_L(scene, ls, u[4], u[5], time);
Spectrum Le(li.L);
RayDifferential photonRay(li.ray);
Normal Nl(li.N);
if (li.pdf == 0.f || Le.IsBlack()) continue;
Spectrum alpha = (AbsDot(Nl, photonRay.d) * Le) / (li.pdf * lightPdf);
if (!alpha.IsBlack()) {
// Follow photon path through scene and record intersections
PBRT_PHOTON_MAP_STARTED_RAY_PATH(&photonRay, &alpha);
bool specularPath = true;
int nIntersections = 0;
auto optPhotonIsect = scene.Intersect(photonRay);
while (optPhotonIsect) {
++nIntersections;
// Handle photon/surface intersection
alpha *= renderer->Transmittance(scene, photonRay, NULL, rng, arena);
BSDF *photonBSDF = optPhotonIsect->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(optPhotonIsect->dg.p, alpha, wo);
bool depositedPhoton = false;
if (specularPath && nIntersections > 1) {
if (!causticDone) {
PBRT_PHOTON_MAP_DEPOSITED_CAUSTIC_PHOTON(&optPhotonIsect->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(&optPhotonIsect->dg, &alpha, &wo);
depositedPhoton = true;
localDirectPhotons.push_back(photon);
}
else if (nIntersections > 1 && !indirectDone) {
PBRT_PHOTON_MAP_DEPOSITED_INDIRECT_PHOTON(&optPhotonIsect->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 = optPhotonIsect->dg.nn;
n = Faceforward(n, -photonRay.d);
localRadiancePhotons.push_back(RadiancePhoton(optPhotonIsect->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(optPhotonIsect->dg.p, wi, photonRay,
optPhotonIsect->rayEpsilon);
optPhotonIsect = scene.Intersect(photonRay);
}
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 PhotonIntegrator::buildPhotonMap(Scene& scene)
{
if (scene.lights.size() <= 0)
return;
causticPhotons.clear();
indirectPhotons.clear();
bool causticDone = 0 , indirectDone = 0;
int nShot = 0;
bool specularPath;
int nIntersections;
Intersection inter;
Real lightPickProb = 1.f / scene.lights.size();
while (!causticDone || !indirectDone)
{
nShot++;
/* generate initial photon ray */
int k = (int)(rng.randFloat() * scene.lights.size());
Vector3 lightPos , lightDir;
Real emissionPdf , directPdfArea , cosAtLight;
Color3 alpha;
AbstractLight *l = scene.lights[k];
alpha = l->emit(scene.sceneSphere , rng.randVector3() , rng.randVector3() ,
lightPos , lightDir , emissionPdf , &directPdfArea ,
&cosAtLight);
alpha = alpha * cosAtLight / (emissionPdf * lightPickProb);
Ray photonRay(lightPos , lightDir);
if (!alpha.isBlack())
{
specularPath = 1;
nIntersections = 0;
Geometry *g = scene.intersect(photonRay , inter);
while (g != NULL && inter.matId > 0)
{
BSDF bsdf(-photonRay.dir , inter , scene);
nIntersections++;
bool hasNonSpecular = (cmp(bsdf.componentProb.diffuseProb) > 0 ||
cmp(bsdf.componentProb.glossyProb) > 0);
if (hasNonSpecular)
{
Photon photon(inter.p , -photonRay.dir , alpha);
if (specularPath && nIntersections > 1)
{
if (!causticDone)
{
causticPhotons.push_back(photon);
if (causticPhotons.size() == nCausticPhotons)
{
causticDone = 1;
nCausticPaths = nShot;
causticMap = new KdTree<Photon>(causticPhotons);
}
}
}
else
{
if (nIntersections > 1 && !indirectDone)
{
indirectPhotons.push_back(photon);
if (indirectPhotons.size() == nIndirectPhotons)
{
indirectDone = 1;
nIndirectPaths = nShot;
indirectMap = new KdTree<Photon>(indirectPhotons);
}
}
}
}
if (nIntersections > maxPathLength)
break;
/* find new photon ray direction */
/* handle specular reflection and transmission first */
Real pdf , cosWo;
int sampledType;
Color3 bsdfFactor = bsdf.sample(scene , rng.randVector3() ,
photonRay.dir , pdf , cosWo , &sampledType);
if (bsdfFactor.isBlack())
break;
if (sampledType & BSDF_NON_SPECULAR)
specularPath = 0;
// Russian Roulette
Real contProb = bsdf.continueProb;
if (cmp(contProb - 1.f) < 0)
{
if (cmp(rng.randFloat() - contProb) > 0)
break;
pdf *= contProb;
}
alpha = (alpha | bsdfFactor) * (cosWo / pdf);
photonRay.origin = inter.p + photonRay.dir * EPS;
photonRay.tmin = 0.f; photonRay.tmax = INF;
g = scene.intersect(photonRay , inter);
}
}
}
}
void preprocess(const Scene *scene) {
/* Create a sample generator for the preprocess step */
Sampler *sampler = static_cast<Sampler *>(
NoriObjectFactory::createInstance("independent", PropertyList()));
Emitter* distantsDisk = scene->getDistantEmitter();
if(distantsDisk != nullptr ) {
float lngstDir = scene->getBoundingBox().getLongestDirection();
distantsDisk->setMaxRadius(lngstDir);
}
/* Allocate memory for the photon map */
m_photonMap = std::unique_ptr<PhotonMap>(new PhotonMap());
m_photonMap->reserve(m_photonCount);
/* Estimate a default photon radius */
if (m_photonRadius == 0)
m_photonRadius = scene->getBoundingBox().getExtents().norm() / 500.0f;
int storedPhotons = 0;
const std::vector<Emitter *> lights = scene->getEmitters();
int nLights = lights.size();
Color3f tp(1.0f, 1.0f, 1.0f);
cout << "Starting to create "<< m_photonCount << " photons!" << endl;
int percentDone= 0;
int onePercent = int(floor(m_photonCount / 100.0));
// create the expected number of photons
while(storedPhotons < m_photonCount) {
//uniformly sample 1 light (assuming that we only have area lights)
int var = int(std::min(sampler->next1D()*nLights, float(nLights) - 1.0f));
const areaLight* curLight = static_cast<const areaLight *> (lights[var]);
//sample a photon
Photon curPhoton;
Vector3f unQuantDir(0.0f,0.0f,0.0f);
curLight->samplePhoton(sampler, curPhoton, 1, nLights, unQuantDir);
Color3f alpha = curPhoton.getPower();
Color3f tp(1.0f, 1.0f, 1.0f);
//trace the photon
Intersection its;
Ray3f photonRay(curPhoton.getPosition(), unQuantDir);
m_shootedRays++;
if (scene->rayIntersect(photonRay, its)) {
while(true) {
const BSDF* curBSDF = its.mesh->getBSDF();
if (curBSDF->isDiffuse()) {
//store the photon
m_photonMap->push_back(Photon(
its.p /* Position */,
-photonRay.d /* Direction*/,
tp * alpha /* Power */
));
storedPhotons++;
}
if(!(storedPhotons < m_photonCount)) break;
BSDFQueryRecord query = BSDFQueryRecord(its.toLocal(-photonRay.d), Vector3f(0.0f), EMeasure::ESolidAngle);
Color3f fi = curBSDF->sample(query, sampler->next2D());
if(fi.maxCoeff() == 0.0f) break;
tp *= fi;
Vector3f wo = its.toWorld(query.wo);
photonRay = Ray3f(its.p, wo);
//ray escapes the scene
if (!scene->rayIntersect(photonRay, its)) break;
//stop critirium russian roulette
float q = tp.maxCoeff();
if(q < sampler->next1D()) break;
tp /= q;
}
}
if(onePercent != 0) {
if(storedPhotons % onePercent == 0){
int percent = int(floor(storedPhotons / onePercent));
if(percent % 10 == 0 && percentDone != percent){
percentDone = percent;
cout << percent << "%" << endl;
}
}
}
}
/* Build the photon map */
m_photonMap->build();
}