void DipoleSubsurfaceIntegrator::Preprocess(const Scene *scene,
const Camera *camera, const Renderer *renderer) {
if (scene->lights.size() == 0) return;
vector<SurfacePoint> pts;
// Get _SurfacePoint_s for translucent objects in scene
if (filename != "") {
// Initialize _SurfacePoint_s from file
vector<float> fpts;
if (ReadFloatFile(filename.c_str(), &fpts)) {
if ((fpts.size() % 8) != 0)
Error("Excess values (%d) in points file \"%s\"", int(fpts.size() % 8),
filename.c_str());
for (u_int i = 0; i < fpts.size(); i += 8)
pts.push_back(SurfacePoint(Point(fpts[i], fpts[i+1], fpts[i+2]),
Normal(fpts[i+3], fpts[i+4], fpts[i+5]),
fpts[i+6], fpts[i+7]));
}
}
if (pts.size() == 0) {
Point pCamera = camera->CameraToWorld(camera->shutterOpen,
Point(0, 0, 0));
FindPoissonPointDistribution(pCamera, camera->shutterOpen,
minSampleDist, scene, &pts);
}
// Compute irradiance values at sample points
RNG rng;
MemoryArena arena;
PBRT_SUBSURFACE_STARTED_COMPUTING_IRRADIANCE_VALUES();
ProgressReporter progress(pts.size(), "Computing Irradiances");
for (uint32_t i = 0; i < pts.size(); ++i) {
SurfacePoint &sp = pts[i];
Spectrum E(0.f);
for (uint32_t j = 0; j < scene->lights.size(); ++j) {
// Add irradiance from light at point
const Light *light = scene->lights[j];
Spectrum Elight = 0.f;
int nSamples = RoundUpPow2(light->nSamples);
uint32_t scramble[2] = { rng.RandomUInt(), rng.RandomUInt() };
uint32_t compScramble = rng.RandomUInt();
for (int s = 0; s < nSamples; ++s) {
float lpos[2];
Sample02(s, scramble, lpos);
float lcomp = VanDerCorput(s, compScramble);
LightSample ls(lpos[0], lpos[1], lcomp);
Vector wi;
float lightPdf;
VisibilityTester visibility;
Spectrum Li = light->Sample_L(sp.p, sp.rayEpsilon,
ls, camera->shutterOpen, &wi, &lightPdf, &visibility);
if (Dot(wi, sp.n) <= 0.) continue;
if (Li.IsBlack() || lightPdf == 0.f) continue;
Li *= visibility.Transmittance(scene, renderer, NULL, rng, arena);
if (visibility.Unoccluded(scene))
Elight += Li * AbsDot(wi, sp.n) / lightPdf;
}
E += Elight / nSamples;
}
if (E.y() > 0.f)
{
irradiancePoints.push_back(IrradiancePoint(sp, E));
PBRT_SUBSURFACE_COMPUTED_IRRADIANCE_AT_POINT(&sp, &E);
}
arena.FreeAll();
progress.Update();
}
progress.Done();
PBRT_SUBSURFACE_FINISHED_COMPUTING_IRRADIANCE_VALUES();
// Create octree of clustered irradiance samples
octree = octreeArena.Alloc<SubsurfaceOctreeNode>();
for (uint32_t i = 0; i < irradiancePoints.size(); ++i)
octreeBounds = Union(octreeBounds, irradiancePoints[i].p);
for (uint32_t i = 0; i < irradiancePoints.size(); ++i)
octree->Insert(octreeBounds, &irradiancePoints[i], octreeArena);
octree->InitHierarchy();
}
void SurfacePointTask::Run() {
// Declare common variables for _SurfacePointTask::Run()_
RNG rng(37 * taskNum);
MemoryArena arena;
vector<SurfacePoint> candidates;
while (true) {
int pathsTraced, raysTraced = 0;
for (pathsTraced = 0; pathsTraced < 20000; ++pathsTraced) {
// Follow ray path and attempt to deposit candidate sample points
Vector dir = UniformSampleSphere(rng.RandomFloat(), rng.RandomFloat());
Ray ray(origin, dir, 0.f, INFINITY, time);
while (ray.depth < 30) {
// Find ray intersection with scene geometry or bounding sphere
++raysTraced;
bool hitOnSphere = false;
auto optIsect = scene.Intersect(ray);
if (!optIsect) {
optIsect = sphere.Intersect(ray);
if (!optIsect)
break;
hitOnSphere = true;
}
DifferentialGeometry &hitGeometry = optIsect->dg;
hitGeometry.nn = Faceforward(hitGeometry.nn, -ray.d);
// Store candidate sample point at ray intersection if appropriate
if (!hitOnSphere && ray.depth >= 3 &&
optIsect->GetBSSRDF(RayDifferential(ray), arena) != NULL) {
float area = M_PI * (minSampleDist / 2.f) * (minSampleDist / 2.f);
candidates.push_back(SurfacePoint(hitGeometry.p, hitGeometry.nn,
area, optIsect->rayEpsilon));
}
// Generate random ray from intersection point
Vector dir = UniformSampleSphere(rng.RandomFloat(), rng.RandomFloat());
dir = Faceforward(dir, hitGeometry.nn);
ray = Ray(hitGeometry.p, dir, ray, optIsect->rayEpsilon);
}
arena.FreeAll();
}
// Make first pass through candidate points with reader lock
vector<bool> candidateRejected;
candidateRejected.reserve(candidates.size());
RWMutexLock lock(mutex, READ);
for (uint32_t i = 0; i < candidates.size(); ++i) {
PoissonCheck check(minSampleDist, candidates[i].p);
octree.Lookup(candidates[i].p, check);
candidateRejected.push_back(check.failed);
}
// Make second pass through points with writer lock and update octree
lock.UpgradeToWrite();
if (repeatedFails >= maxFails)
return;
totalPathsTraced += pathsTraced;
totalRaysTraced += raysTraced;
int oldMaxRepeatedFails = maxRepeatedFails;
for (uint32_t i = 0; i < candidates.size(); ++i) {
if (candidateRejected[i]) {
// Update for rejected candidate point
++repeatedFails;
maxRepeatedFails = max(maxRepeatedFails, repeatedFails);
if (repeatedFails >= maxFails)
return;
}
else {
// Recheck candidate point and possibly add to octree
SurfacePoint &sp = candidates[i];
PoissonCheck check(minSampleDist, sp.p);
octree.Lookup(sp.p, check);
if (check.failed) {
// Update for rejected candidate point
++repeatedFails;
maxRepeatedFails = max(maxRepeatedFails, repeatedFails);
if (repeatedFails >= maxFails)
return;
}
else {
++numPointsAdded;
repeatedFails = 0;
Vector delta(minSampleDist, minSampleDist, minSampleDist);
octree.Add(sp, BBox(sp.p-delta, sp.p+delta));
PBRT_SUBSURFACE_ADDED_POINT_TO_OCTREE(&sp, minSampleDist);
surfacePoints.push_back(sp);
}
}
}
// Stop following paths if not finding new points
if (repeatedFails > oldMaxRepeatedFails) {
int delta = repeatedFails - oldMaxRepeatedFails;
prog.Update(delta);
}
if (totalPathsTraced > 50000 && numPointsAdded == 0) {
Warning("There don't seem to be any objects with BSSRDFs "
"in this scene. Giving up.");
return;
}
candidates.erase(candidates.begin(), candidates.end());
}
}
