bool TraceBase::handleSurface(SurfaceScatterEvent &event, IntersectionTemporary &data,
IntersectionInfo &info, const Medium *&medium,
int bounce, bool adjoint, bool enableLightSampling, Ray &ray,
Vec3f &throughput, Vec3f &emission, bool &wasSpecular,
Medium::MediumState &state, Vec3f *transmittance)
{
const Bsdf &bsdf = *info.bsdf;
// For forward events, the transport direction does not matter (since wi = -wo)
Vec3f transparency = bsdf.eval(event.makeForwardEvent(), false);
float transparencyScalar = transparency.avg();
Vec3f wo;
if (event.sampler->nextBoolean(transparencyScalar) ){
wo = ray.dir();
event.pdf = transparencyScalar;
event.weight = transparency/transparencyScalar;
event.sampledLobe = BsdfLobes::ForwardLobe;
throughput *= event.weight;
} else {
if (!adjoint) {
if (enableLightSampling && bounce < _settings.maxBounces - 1)
emission += estimateDirect(event, medium, bounce + 1, ray, transmittance)*throughput;
if (info.primitive->isEmissive() && bounce >= _settings.minBounces) {
if (!enableLightSampling || wasSpecular || !info.primitive->isSamplable())
emission += info.primitive->evalDirect(data, info)*throughput;
}
}
event.requestedLobe = BsdfLobes::AllLobes;
if (!bsdf.sample(event, adjoint))
return false;
wo = event.frame.toGlobal(event.wo);
if (!isConsistent(event, wo))
return false;
throughput *= event.weight;
wasSpecular = event.sampledLobe.hasSpecular();
if (!wasSpecular)
ray.setPrimaryRay(false);
}
bool geometricBackside = (wo.dot(info.Ng) < 0.0f);
medium = info.primitive->selectMedium(medium, geometricBackside);
state.reset();
ray = ray.scatter(ray.hitpoint(), wo, info.epsilon);
return true;
}
void LightTracer::traceSample(PathSampleGenerator &sampler)
{
float lightPdf;
const Primitive *light = chooseLightAdjoint(sampler, lightPdf);
const Medium *medium = light->extMedium().get();
PositionSample point;
if (!light->samplePosition(sampler, point))
return;
DirectionSample direction;
if (!light->sampleDirection(sampler, point, direction))
return;
sampler.advancePath();
Vec3f throughput(point.weight/lightPdf);
LensSample splat;
if (_settings.minBounces == 0 && !light->isInfinite() && _scene->cam().sampleDirect(point.p, sampler, splat)) {
Ray shadowRay(point.p, splat.d);
shadowRay.setFarT(splat.dist);
Vec3f transmission = generalizedShadowRay(shadowRay, medium, nullptr, 0);
if (transmission != 0.0f) {
Vec3f value = throughput*transmission*splat.weight
*light->evalDirectionalEmission(point, DirectionSample(splat.d));
_splatBuffer->splatFiltered(splat.pixel, value);
}
}
sampler.advancePath();
Ray ray(point.p, direction.d);
throughput *= direction.weight;
VolumeScatterEvent volumeEvent;
SurfaceScatterEvent surfaceEvent;
IntersectionTemporary data;
IntersectionInfo info;
Medium::MediumState state;
state.reset();
Vec3f emission(0.0f);
int bounce = 0;
bool wasSpecular = true;
bool didHit = _scene->intersect(ray, data, info);
while ((didHit || medium) && bounce < _settings.maxBounces - 1) {
bool hitSurface = true;
if (medium) {
volumeEvent = VolumeScatterEvent(&sampler, throughput, ray.pos(), ray.dir(), ray.farT());
if (!medium->sampleDistance(volumeEvent, state))
break;
throughput *= volumeEvent.weight;
volumeEvent.weight = Vec3f(1.0f);
hitSurface = volumeEvent.t == volumeEvent.maxT;
if (hitSurface && !didHit)
break;
}
if (hitSurface) {
surfaceEvent = makeLocalScatterEvent(data, info, ray, &sampler);
Vec3f weight;
Vec2f pixel;
if (surfaceLensSample(_scene->cam(), surfaceEvent, medium, bounce + 1, ray, weight, pixel))
_splatBuffer->splatFiltered(pixel, weight*throughput);
if (!handleSurface(surfaceEvent, data, info, medium, bounce,
true, false, ray, throughput, emission, wasSpecular, state))
break;
} else {
volumeEvent.p += volumeEvent.t*volumeEvent.wi;
Vec3f weight;
Vec2f pixel;
if (volumeLensSample(_scene->cam(), volumeEvent, medium, bounce + 1, ray, weight, pixel))
_splatBuffer->splatFiltered(pixel, weight*throughput);
if (!handleVolume(volumeEvent, medium, bounce,
true, false, ray, throughput, emission, wasSpecular, state))
break;
}
if (throughput.max() == 0.0f)
break;
if (std::isnan(ray.dir().sum() + ray.pos().sum()))
break;
if (std::isnan(throughput.sum()))
break;
sampler.advancePath();
bounce++;
if (bounce < _settings.maxBounces)
didHit = _scene->intersect(ray, data, info);
}
}
void PhotonTracer::tracePhoton(SurfacePhotonRange &surfaceRange, VolumePhotonRange &volumeRange,
PathSampleGenerator &sampler)
{
float lightPdf;
const Primitive *light = chooseLightAdjoint(sampler, lightPdf);
PositionSample point;
if (!light->samplePosition(sampler, point))
return;
DirectionSample direction;
if (!light->sampleDirection(sampler, point, direction))
return;
sampler.advancePath();
Ray ray(point.p, direction.d);
Vec3f throughput(point.weight*direction.weight/lightPdf);
SurfaceScatterEvent event;
IntersectionTemporary data;
IntersectionInfo info;
Medium::MediumState state;
state.reset();
Vec3f emission(0.0f);
const Medium *medium = nullptr; // TODO: Media
int bounce = 0;
bool wasSpecular = true;
bool hitSurface = true;
bool didHit = _scene->intersect(ray, data, info);
while ((didHit || medium) && bounce < _settings.maxBounces - 1) {
if (medium) {
MediumSample mediumSample;
if (!medium->sampleDistance(sampler, ray, state, mediumSample))
break;
throughput *= mediumSample.weight;
hitSurface = mediumSample.exited;
if (!hitSurface) {
if (!volumeRange.full()) {
VolumePhoton &p = volumeRange.addPhoton();
p.pos = mediumSample.p;
p.dir = ray.dir();
p.power = throughput;
}
PhaseSample phaseSample;
if (!mediumSample.phase->sample(sampler, ray.dir(), phaseSample))
break;
ray = ray.scatter(mediumSample.p, phaseSample.w, 0.0f);
ray.setPrimaryRay(false);
throughput *= phaseSample.weight;
}
}
if (hitSurface) {
if (!info.bsdf->lobes().isPureSpecular() && !surfaceRange.full()) {
Photon &p = surfaceRange.addPhoton();
p.pos = info.p;
p.dir = ray.dir();
p.power = throughput*std::abs(info.Ns.dot(ray.dir())/info.Ng.dot(ray.dir()));
}
}
if (volumeRange.full() && surfaceRange.full())
break;
if (hitSurface) {
event = makeLocalScatterEvent(data, info, ray, &sampler);
if (!handleSurface(event, data, info, medium, bounce,
true, false, ray, throughput, emission, wasSpecular, state))
break;
}
if (throughput.max() == 0.0f)
break;
if (std::isnan(ray.dir().sum() + ray.pos().sum()))
break;
if (std::isnan(throughput.sum()))
break;
sampler.advancePath();
bounce++;
if (bounce < _settings.maxBounces)
didHit = _scene->intersect(ray, data, info);
}
}
