Spectrum FresnelSpecular::Sample_f(const Vector3f &wo, Vector3f *wi,
const Point2f &u, Float *pdf,
BxDFType *sampledType) const {
Float F = FrDielectric(CosTheta(wo), etaA, etaB);
if (u[0] < F) {
// Compute specular reflection for _FresnelSpecular_
// Compute perfect specular reflection direction
*wi = Vector3f(-wo.x, -wo.y, wo.z);
if (sampledType)
*sampledType = BxDFType(BSDF_SPECULAR | BSDF_REFLECTION);
*pdf = F;
return F * R / AbsCosTheta(*wi);
} else {
// Compute specular transmission for _FresnelSpecular_
// Figure out which $\eta$ is incident and which is transmitted
bool entering = CosTheta(wo) > 0;
Float etaI = entering ? etaA : etaB;
Float etaT = entering ? etaB : etaA;
// Compute ray direction for specular transmission
if (!Refract(wo, Faceforward(Normal3f(0, 0, 1), wo), etaI / etaT, wi))
return 0;
Spectrum ft = T * (1 - F);
// Account for non-symmetry with transmission to different medium
if (mode == TransportMode::Radiance)
ft *= (etaI * etaI) / (etaT * etaT);
if (sampledType)
*sampledType = BxDFType(BSDF_SPECULAR | BSDF_TRANSMISSION);
*pdf = 1 - F;
return ft / AbsCosTheta(*wi);
}
}
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 IrradianceCacheIntegrator::indirectLo(const Point &p,
const Normal &ng, float pixelSpacing, const Vector &wo,
float rayEpsilon, BSDF *bsdf, BxDFType flags, RNG &rng,
const Scene *scene, const Renderer *renderer,
MemoryArena &arena) const {
if (bsdf->NumComponents(flags) == 0)
return Spectrum(0.);
Spectrum E;
Vector wi;
// Get irradiance _E_ and average incident direction _wi_ at point _p_
if (!interpolateE(scene, p, ng, &E, &wi)) {
// Compute irradiance at current point
PBRT_IRRADIANCE_CACHE_STARTED_COMPUTING_IRRADIANCE(const_cast<Point *>(&p), const_cast<Normal *>(&ng));
uint32_t scramble[2] = { rng.RandomUInt(), rng.RandomUInt() };
float minHitDistance = INFINITY;
Vector wAvg(0,0,0);
Spectrum LiSum = 0.f;
for (int i = 0; i < nSamples; ++i) {
// Sample direction for irradiance estimate ray
float u[2];
Sample02(i, scramble, u);
Vector w = CosineSampleHemisphere(u[0], u[1]);
RayDifferential r(p, bsdf->LocalToWorld(w), rayEpsilon);
r.d = Faceforward(r.d, ng);
// Trace ray to sample radiance for irradiance estimate
PBRT_IRRADIANCE_CACHE_STARTED_RAY(&r);
Spectrum L = pathL(r, scene, renderer, rng, arena);
LiSum += L;
wAvg += r.d * L.y();
minHitDistance = min(minHitDistance, r.maxt);
PBRT_IRRADIANCE_CACHE_FINISHED_RAY(&r, r.maxt, &L);
}
E = (M_PI / float(nSamples)) * LiSum;
PBRT_IRRADIANCE_CACHE_FINISHED_COMPUTING_IRRADIANCE(const_cast<Point *>(&p), const_cast<Normal *>(&ng));
// Add computed irradiance value to cache
// Compute irradiance sample's contribution extent and bounding box
float maxDist = maxSamplePixelSpacing * pixelSpacing;
float minDist = minSamplePixelSpacing * pixelSpacing;
float contribExtent = Clamp(minHitDistance / 2.f, minDist, maxDist);
BBox sampleExtent(p);
sampleExtent.Expand(contribExtent);
PBRT_IRRADIANCE_CACHE_ADDED_NEW_SAMPLE(const_cast<Point *>(&p), const_cast<Normal *>(&ng), contribExtent, &E, &wAvg, pixelSpacing);
// Allocate _IrradianceSample_, get write lock, add to octree
IrradianceSample *sample = new IrradianceSample(E, p, ng, wAvg,
contribExtent);
RWMutexLock lock(*mutex, WRITE);
octree->Add(sample, sampleExtent);
wi = wAvg;
}
// Compute reflected radiance due to irradiance and BSDF
if (wi.LengthSquared() == 0.f) return Spectrum(0.);
return bsdf->f(wo, Normalize(wi), flags) * E;
}
Spectrum LPhoton(KdTree<Photon> *map, int nPaths, int nLookup,
MemoryArena &arena, BSDF *bsdf, RNG &rng, const Intersection &isect,
const Vector &wo, float maxDistSquared) {
Spectrum L(0.);
BxDFType nonSpecular = BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_DIFFUSE | BSDF_GLOSSY);
if (map && bsdf->NumComponents(nonSpecular) > 0) {
PBRT_PHOTON_MAP_STARTED_LOOKUP(const_cast<DifferentialGeometry *>(&isect.dg));
// Do photon map lookup at intersection point
PhotonProcess proc(nLookup, arena.Alloc<ClosePhoton>(nLookup));
map->Lookup(isect.dg.p, proc, maxDistSquared);
// Estimate reflected radiance due to incident photons
ClosePhoton *photons = proc.photons;
int nFound = proc.nFound;
Normal Nf = Faceforward(bsdf->dgShading.nn, wo);
if (bsdf->NumComponents(BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_GLOSSY)) > 0) {
// Compute exitant radiance from photons for glossy surface
for (int i = 0; i < nFound; ++i) {
const Photon *p = photons[i].photon;
float k = kernel(p, isect.dg.p, maxDistSquared);
L += (k / (nPaths * maxDistSquared)) * bsdf->f(wo, p->wi) *
p->alpha;
}
}
else {
// Compute exitant radiance from photons for diffuse surface
Spectrum Lr(0.), Lt(0.);
for (int i = 0; i < nFound; ++i) {
if (Dot(Nf, photons[i].photon->wi) > 0.f) {
float k = kernel(photons[i].photon, isect.dg.p,
maxDistSquared);
Lr += (k / (nPaths * maxDistSquared)) * photons[i].photon->alpha;
}
else {
float k = kernel(photons[i].photon, isect.dg.p,
maxDistSquared);
Lt += (k / (nPaths * maxDistSquared)) * photons[i].photon->alpha;
}
}
const int sqrtRhoSamples = 4;
float rhoRSamples[2*sqrtRhoSamples*sqrtRhoSamples];
StratifiedSample2D(rhoRSamples, sqrtRhoSamples, sqrtRhoSamples, rng);
float rhoTSamples[2*sqrtRhoSamples*sqrtRhoSamples];
StratifiedSample2D(rhoTSamples, sqrtRhoSamples, sqrtRhoSamples, rng);
L += Lr * bsdf->rho(wo, sqrtRhoSamples*sqrtRhoSamples, rhoRSamples,
BSDF_ALL_REFLECTION) * INV_PI +
Lt * bsdf->rho(wo, sqrtRhoSamples*sqrtRhoSamples, rhoTSamples,
BSDF_ALL_TRANSMISSION) * INV_PI;
}
PBRT_PHOTON_MAP_FINISHED_LOOKUP(const_cast<DifferentialGeometry *>(&isect.dg),
proc.nFound, proc.nLookup, &L);
}
return L;
}
void SurfaceInteraction::SetShadingGeometry(const Vector3f &dpdus,
const Vector3f &dpdvs,
const Normal3f &dndus,
const Normal3f &dndvs,
bool orientationIsAuthoritative) {
// Compute _shading.n_ for _SurfaceInteraction_
shading.n = Normalize((Normal3f)Cross(dpdus, dpdvs));
if (shape && (shape->reverseOrientation ^ shape->transformSwapsHandedness))
shading.n = -shading.n;
if (orientationIsAuthoritative)
n = Faceforward(n, shading.n);
else
shading.n = Faceforward(shading.n, n);
// Initialize _shading_ partial derivative values
shading.dpdu = dpdus;
shading.dpdv = dpdvs;
shading.dndu = dndus;
shading.dndv = dndvs;
}
Spectrum SpecularTransmission::Sample_f(const Vector3f &wo, Vector3f *wi,
const Point2f &sample, Float *pdf,
BxDFType *sampledType) const {
// Figure out which $\eta$ is incident and which is transmitted
bool entering = CosTheta(wo) > 0;
Float etaI = entering ? etaA : etaB;
Float etaT = entering ? etaB : etaA;
// Compute ray direction for specular transmission
if (!Refract(wo, Faceforward(Normal3f(0, 0, 1), wo), etaI / etaT, wi))
return 0;
*pdf = 1;
Spectrum ft = T * (Spectrum(1.) - fresnel.Evaluate(CosTheta(*wi)));
// Account for non-symmetry with transmission to different medium
if (mode == TransportMode::Radiance) ft *= (etaI * etaI) / (etaT * etaT);
return ft / AbsCosTheta(*wi);
}
// AmbientOcclusionIntegrator Method Definitions
Spectrum AmbientOcclusionIntegrator::Li(const Scene *scene, const Renderer *renderer,
const RayDifferential &ray, const Intersection &isect,
const Sample *sample, RNG &rng, MemoryArena &arena, int wavelength) const {
BSDF *bsdf = isect.GetBSDF(ray, arena, wavelength);
const Point &p = bsdf->dgShading.p;
Normal n = Faceforward(isect.dg.nn, -ray.d);
uint32_t scramble[2] = { rng.RandomUInt(), rng.RandomUInt() };
float u[2];
int nClear = 0;
for (int i = 0; i < nSamples; ++i) {
Sample02(i, scramble, u);
Vector w = UniformSampleSphere(u[0], u[1]);
if (Dot(w, n) < 0.) w = -w;
Ray r(p, w, .01f, maxDist);
if (!scene->IntersectP(r)) ++nClear;
}
return Spectrum(float(nClear) / float(nSamples));
}
bool RealisticCamera::IntersectSphericalElement(Float radius, Float zCenter,
const Ray &ray, Float *t,
Normal3f *n) {
// Compute _t0_ and _t1_ for ray--element intersection
Point3f o = ray.o - Vector3f(0, 0, zCenter);
Float A = ray.d.x * ray.d.x + ray.d.y * ray.d.y + ray.d.z * ray.d.z;
Float B = 2 * (ray.d.x * o.x + ray.d.y * o.y + ray.d.z * o.z);
Float C = o.x * o.x + o.y * o.y + o.z * o.z - radius * radius;
Float t0, t1;
if (!Quadratic(A, B, C, &t0, &t1)) return false;
// Select intersection $t$ based on ray direction and element curvature
bool useCloserT = (ray.d.z > 0) ^ (radius < 0);
*t = useCloserT ? std::min(t0, t1) : std::max(t0, t1);
if (*t < 0) return false;
// Compute surface normal of element at ray intersection point
*n = Normal3f(Vector3f(o + *t * ray.d));
*n = Faceforward(Normalize(*n), -ray.d);
return true;
}
void Material::Bump(const Reference<Texture<float> > &d,
const DifferentialGeometry &dgGeom,
const DifferentialGeometry &dgs,
DifferentialGeometry *dgBump) {
// Compute offset positions and evaluate displacement texture
DifferentialGeometry dgEval = dgs;
// Shift _dgEval_ _du_ in the $u$ direction
float du = .5f * (fabsf(dgs.dudx) + fabsf(dgs.dudy));
if (du == 0.f) du = .01f;
dgEval.p = dgs.p + du * dgs.dpdu;
dgEval.u = dgs.u + du;
dgEval.nn = Normalize((Normal)Cross(dgs.dpdu, dgs.dpdv) +
du * dgs.dndu);
float uDisplace = d->Evaluate(dgEval);
// Shift _dgEval_ _dv_ in the $v$ direction
float dv = .5f * (fabsf(dgs.dvdx) + fabsf(dgs.dvdy));
if (dv == 0.f) dv = .01f;
dgEval.p = dgs.p + dv * dgs.dpdv;
dgEval.u = dgs.u;
dgEval.v = dgs.v + dv;
dgEval.nn = Normalize((Normal)Cross(dgs.dpdu, dgs.dpdv) +
dv * dgs.dndv);
float vDisplace = d->Evaluate(dgEval);
float displace = d->Evaluate(dgs);
// Compute bump-mapped differential geometry
*dgBump = dgs;
dgBump->dpdu = dgs.dpdu + (uDisplace - displace) / du * Vector(dgs.nn) +
displace * Vector(dgs.dndu);
dgBump->dpdv = dgs.dpdv + (vDisplace - displace) / dv * Vector(dgs.nn) +
displace * Vector(dgs.dndv);
dgBump->nn = Normal(Normalize(Cross(dgBump->dpdu, dgBump->dpdv)));
if (dgs.shape->ReverseOrientation ^ dgs.shape->TransformSwapsHandedness)
dgBump->nn *= -1.f;
// Orient shading normal to match geometric normal
dgBump->nn = Faceforward(dgBump->nn, dgGeom.nn);
}
Spectrum IrradianceCacheIntegrator::Li(const Scene *scene,
const Renderer *renderer, const RayDifferential &ray, const Intersection &isect,
const Sample *sample, RNG &rng, MemoryArena &arena) const {
Spectrum L(0.);
// Evaluate BSDF at hit point
BSDF *bsdf = isect.GetBSDF(ray, arena);
Vector wo = -ray.d;
const Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
L += isect.Le(wo);
// Compute direct lighting for irradiance cache
L += UniformSampleAllLights(scene, renderer, arena, p, n, wo,
isect.rayEpsilon, ray.time, bsdf, sample, rng,
lightSampleOffsets, bsdfSampleOffsets);
// Compute indirect lighting for irradiance cache
if (ray.depth + 1 < maxSpecularDepth) {
Vector wi;
// Trace rays for specular reflection and refraction
L += SpecularReflect(ray, bsdf, rng, isect, renderer, scene, sample,
arena);
L += SpecularTransmit(ray, bsdf, rng, isect, renderer, scene, sample,
arena);
}
// Estimate indirect lighting with irradiance cache
Normal ng = isect.dg.nn;
ng = Faceforward(ng, wo);
// Compute pixel spacing in world space at intersection point
float pixelSpacing = sqrtf(Cross(isect.dg.dpdx, isect.dg.dpdy).Length());
BxDFType flags = BxDFType(BSDF_REFLECTION | BSDF_DIFFUSE | BSDF_GLOSSY);
L += indirectLo(p, ng, pixelSpacing, wo, isect.rayEpsilon,
bsdf, flags, rng, scene, renderer, arena);
flags = BxDFType(BSDF_TRANSMISSION | BSDF_DIFFUSE | BSDF_GLOSSY);
L += indirectLo(p, -ng, pixelSpacing, wo, isect.rayEpsilon,
bsdf, flags, rng, scene, renderer, arena);
return L;
}
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;
}
Spectrum PhotonIntegrator::Li(const Scene *scene, const Renderer *renderer,
const RayDifferential &ray, const Intersection &isect,
const Sample *sample, RNG &rng, MemoryArena &arena) 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 pbrt::Point
BSDF *bsdf = isect.GetBSDF(ray, arena);
const pbrt::Point &p = bsdf->dgShading.p;
const Normal &n = bsdf->dgShading.nn;
L += UniformSampleAllLights(scene, renderer, arena, p, n,
wo, isect.rayEpsilon, ray.time, bsdf, sample, rng,
lightSampleOffsets, bsdfSampleOffsets);
// Compute caustic lighting for photon map integrator
ClosePhoton *lookupBuf = arena.Alloc<ClosePhoton>(nLookup);
L += LPhoton(causticMap, nCausticPaths, nLookup, lookupBuf, bsdf,
rng, isect, wo, maxDistSquared);
// Compute indirect lighting for photon map integrator
if (finalGather && indirectMap != NULL) {
#if 1
// Do one-bounce final gather for photon map
BxDFType nonSpecular = BxDFType(BSDF_REFLECTION |
BSDF_TRANSMISSION | BSDF_DIFFUSE | BSDF_GLOSSY);
if (bsdf->NumComponents(nonSpecular) > 0) {
// Find indirect photons around point for importance sampling
const uint32_t nIndirSamplePhotons = 50;
PhotonProcess proc(nIndirSamplePhotons,
arena.Alloc<ClosePhoton>(nIndirSamplePhotons));
float searchDist2 = maxDistSquared;
while (proc.nFound < nIndirSamplePhotons) {
float md2 = searchDist2;
proc.nFound = 0;
indirectMap->Lookup(p, proc, md2);
searchDist2 *= 2.f;
}
// Copy photon directions to local array
Vector *photonDirs = arena.Alloc<Vector>(nIndirSamplePhotons);
for (uint32_t i = 0; i < nIndirSamplePhotons; ++i)
photonDirs[i] = proc.photons[i].photon->wi;
// Use BSDF to do final gathering
Spectrum Li = 0.;
for (int i = 0; i < gatherSamples; ++i) {
// Sample random direction from BSDF for final gather ray
Vector wi;
float pdf;
BSDFSample bsdfSample(sample, bsdfGatherSampleOffsets, i);
Spectrum fr = bsdf->Sample_f(wo, &wi, bsdfSample,
&pdf, BxDFType(BSDF_ALL & ~BSDF_SPECULAR));
if (fr.IsBlack() || pdf == 0.f) continue;
Assert(pdf >= 0.f);
// Trace BSDF final gather ray and accumulate radiance
RayDifferential bounceRay(p, wi, ray, isect.rayEpsilon);
Intersection gatherIsect;
if (scene->Intersect(bounceRay, &gatherIsect)) {
// Compute exitant radiance _Lindir_ using radiance photons
Spectrum Lindir = 0.f;
Normal nGather = gatherIsect.dg.nn;
nGather = Faceforward(nGather, -bounceRay.d);
RadiancePhotonProcess proc(nGather);
float md2 = INFINITY;
radianceMap->Lookup(gatherIsect.dg.p, proc, md2);
if (proc.photon != NULL)
Lindir = proc.photon->Lo;
Lindir *= renderer->Transmittance(scene, bounceRay, NULL, rng, arena);
// Compute MIS weight for BSDF-sampled gather ray
// Compute PDF for photon-sampling of direction _wi_
float photonPdf = 0.f;
float conePdf = UniformConePdf(cosGatherAngle);
for (uint32_t j = 0; j < nIndirSamplePhotons; ++j)
if (Dot(photonDirs[j], wi) > .999f * cosGatherAngle)
photonPdf += conePdf;
photonPdf /= nIndirSamplePhotons;
float wt = PowerHeuristic(gatherSamples, pdf, gatherSamples, photonPdf);
Li += fr * Lindir * (AbsDot(wi, n) * wt / pdf);
}
}
L += Li / gatherSamples;
// Use nearby photons to do final gathering
Li = 0.;
for (int i = 0; i < gatherSamples; ++i) {
// Sample random direction using photons for final gather ray
BSDFSample gatherSample(sample, indirGatherSampleOffsets, i);
int photonNum = min((int)nIndirSamplePhotons - 1,
Floor2Int(gatherSample.uComponent * nIndirSamplePhotons));
// Sample gather ray direction from _photonNum_
Vector vx, vy;
CoordinateSystem(photonDirs[photonNum], &vx, &vy);
Vector wi = UniformSampleCone(gatherSample.uDir[0], gatherSample.uDir[1],
cosGatherAngle, vx, vy, photonDirs[photonNum]);
// Trace photon-sampled final gather ray and accumulate radiance
Spectrum fr = bsdf->f(wo, wi);
if (fr.IsBlack()) continue;
RayDifferential bounceRay(p, wi, ray, isect.rayEpsilon);
Intersection gatherIsect;
PBRT_PHOTON_MAP_STARTED_GATHER_RAY(&bounceRay);
if (scene->Intersect(bounceRay, &gatherIsect)) {
// Compute exitant radiance _Lindir_ using radiance photons
Spectrum Lindir = 0.f;
Normal nGather = gatherIsect.dg.nn;
nGather = Faceforward(nGather, -bounceRay.d);
RadiancePhotonProcess proc(nGather);
float md2 = INFINITY;
radianceMap->Lookup(gatherIsect.dg.p, proc, md2);
if (proc.photon != NULL)
Lindir = proc.photon->Lo;
Lindir *= renderer->Transmittance(scene, bounceRay, NULL, rng, arena);
// Compute PDF for photon-sampling of direction _wi_
float photonPdf = 0.f;
float conePdf = UniformConePdf(cosGatherAngle);
for (uint32_t j = 0; j < nIndirSamplePhotons; ++j)
if (Dot(photonDirs[j], wi) > .999f * cosGatherAngle)
photonPdf += conePdf;
photonPdf /= nIndirSamplePhotons;
// Compute MIS weight for photon-sampled gather ray
float bsdfPdf = bsdf->Pdf(wo, wi);
float wt = PowerHeuristic(gatherSamples, photonPdf, gatherSamples, bsdfPdf);
Li += fr * Lindir * AbsDot(wi, n) * wt / photonPdf;
}
PBRT_PHOTON_MAP_FINISHED_GATHER_RAY(&bounceRay);
}
L += Li / gatherSamples;
}
#else
// for debugging / examples: use the photon map directly
Normal nn = Faceforward(n, -ray.d);
RadiancePhotonProcess proc(nn);
float md2 = INFINITY;
radianceMap->Lookup(p, proc, md2);
if (proc.photon)
L += proc.photon->Lo;
#endif
}
else
L += LPhoton(indirectMap, nIndirectPaths, nLookup, lookupBuf,
bsdf, rng, isect, wo, maxDistSquared);
if (ray.depth+1 < maxSpecularDepth) {
Vector wi;
// Trace rays for specular reflection and refraction
L += SpecularReflect(ray, bsdf, rng, isect, renderer, scene, sample,
arena);
L += SpecularTransmit(ray, bsdf, rng, isect, renderer, scene, sample,
arena);
}
return L;
}
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 CreateRadianceProbes::Render(const Scene *scene) {
// Compute scene bounds and initialize probe integrators
if (bbox.pMin.x > bbox.pMax.x)
bbox = scene->WorldBound();
surfaceIntegrator->Preprocess(scene, camera, this);
volumeIntegrator->Preprocess(scene, camera, this);
Sample *origSample = new Sample(NULL, surfaceIntegrator, volumeIntegrator,
scene);
// Compute sampling rate in each dimension
Vector delta = bbox.pMax - bbox.pMin;
int nProbes[3];
for (int i = 0; i < 3; ++i)
nProbes[i] = max(1, Ceil2Int(delta[i] / probeSpacing));
// Allocate SH coefficient vector pointers for sample points
int count = nProbes[0] * nProbes[1] * nProbes[2];
Spectrum **c_in = new Spectrum *[count];
for (int i = 0; i < count; ++i)
c_in[i] = new Spectrum[SHTerms(lmax)];
// Compute random points on surfaces of scene
// Create scene bounding sphere to catch rays that leave the scene
Point sceneCenter;
float sceneRadius;
scene->WorldBound().BoundingSphere(&sceneCenter, &sceneRadius);
Transform ObjectToWorld(Translate(sceneCenter - Point(0,0,0)));
Transform WorldToObject(Inverse(ObjectToWorld));
Reference<Shape> sph = new Sphere(&ObjectToWorld, &WorldToObject,
true, sceneRadius, -sceneRadius, sceneRadius, 360.f);
Reference<Material> nullMaterial = Reference<Material>(NULL);
GeometricPrimitive sphere(sph, nullMaterial, NULL);
vector<Point> surfacePoints;
uint32_t nPoints = 32768, maxDepth = 32;
surfacePoints.reserve(nPoints + maxDepth);
Point pCamera = camera->CameraToWorld(camera->shutterOpen,
Point(0, 0, 0));
surfacePoints.push_back(pCamera);
RNG rng;
while (surfacePoints.size() < nPoints) {
// Generate random path from camera and deposit surface points
Point pray = pCamera;
Vector dir = UniformSampleSphere(rng.RandomFloat(), rng.RandomFloat());
float rayEpsilon = 0.f;
for (uint32_t i = 0; i < maxDepth; ++i) {
Ray ray(pray, dir, rayEpsilon, INFINITY, time);
Intersection isect;
if (!scene->Intersect(ray, &isect) &&
!sphere.Intersect(ray, &isect))
break;
surfacePoints.push_back(ray(ray.maxt));
DifferentialGeometry &hitGeometry = isect.dg;
pray = isect.dg.p;
rayEpsilon = isect.rayEpsilon;
hitGeometry.nn = Faceforward(hitGeometry.nn, -ray.d);
dir = UniformSampleSphere(rng.RandomFloat(), rng.RandomFloat());
dir = Faceforward(dir, hitGeometry.nn);
}
}
// Launch tasks to compute radiance probes at sample points
vector<Task *> tasks;
ProgressReporter prog(count, "Radiance Probes");
for (int i = 0; i < count; ++i)
tasks.push_back(new CreateRadProbeTask(i, nProbes, time,
bbox, lmax, includeDirectInProbes,
includeIndirectInProbes, nIndirSamples,
prog, origSample, surfacePoints,
scene, this, c_in[i]));
EnqueueTasks(tasks);
WaitForAllTasks();
for (uint32_t i = 0; i < tasks.size(); ++i)
delete tasks[i];
prog.Done();
// Write radiance probe coefficients to file
FILE *f = fopen(filename.c_str(), "w");
if (f) {
if (fprintf(f, "%d %d %d\n", lmax, includeDirectInProbes?1:0, includeIndirectInProbes?1:0) < 0 ||
fprintf(f, "%d %d %d\n", nProbes[0], nProbes[1], nProbes[2]) < 0 ||
fprintf(f, "%f %f %f %f %f %f\n", bbox.pMin.x, bbox.pMin.y, bbox.pMin.z,
bbox.pMax.x, bbox.pMax.y, bbox.pMax.z) < 0) {
Error("Error writing radiance file \"%s\" (%s)", filename.c_str(),
strerror(errno));
exit(1);
}
for (int i = 0; i < nProbes[0] * nProbes[1] * nProbes[2]; ++i) {
for (int j = 0; j < SHTerms(lmax); ++j) {
fprintf(f, " ");
if (c_in[i][j].Write(f) == false) {
Error("Error writing radiance file \"%s\" (%s)", filename.c_str(),
strerror(errno));
exit(1);
}
fprintf(f, "\n");
}
fprintf(f, "\n");
}
fclose(f);
}
for (int i = 0; i < nProbes[0] * nProbes[1] * nProbes[2]; ++i)
delete[] c_in[i];
delete[] c_in;
delete origSample;
}
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());
}
}
bool Triangle::Intersect(const Ray &ray, Float *tHit, SurfaceInteraction *isect,
bool testAlphaTexture) const {
ProfilePhase p(Prof::TriIntersect);
++nTests;
// Get triangle vertices in _p0_, _p1_, and _p2_
const Point3f &p0 = mesh->p[v[0]];
const Point3f &p1 = mesh->p[v[1]];
const Point3f &p2 = mesh->p[v[2]];
// Perform ray--triangle intersection test
// Transform triangle vertices to ray coordinate space
// Translate vertices based on ray origin
Point3f p0t = p0 - Vector3f(ray.o);
Point3f p1t = p1 - Vector3f(ray.o);
Point3f p2t = p2 - Vector3f(ray.o);
// Permute components of triangle vertices and ray direction
int kz = MaxDimension(Abs(ray.d));
int kx = kz + 1;
if (kx == 3) kx = 0;
int ky = kx + 1;
if (ky == 3) ky = 0;
Vector3f d = Permute(ray.d, kx, ky, kz);
p0t = Permute(p0t, kx, ky, kz);
p1t = Permute(p1t, kx, ky, kz);
p2t = Permute(p2t, kx, ky, kz);
// Apply shear transformation to translated vertex positions
Float Sx = -d.x / d.z;
Float Sy = -d.y / d.z;
Float Sz = 1.f / d.z;
p0t.x += Sx * p0t.z;
p0t.y += Sy * p0t.z;
p1t.x += Sx * p1t.z;
p1t.y += Sy * p1t.z;
p2t.x += Sx * p2t.z;
p2t.y += Sy * p2t.z;
// Compute edge function coefficients _e0_, _e1_, and _e2_
Float e0 = p1t.x * p2t.y - p1t.y * p2t.x;
Float e1 = p2t.x * p0t.y - p2t.y * p0t.x;
Float e2 = p0t.x * p1t.y - p0t.y * p1t.x;
// Fall back to double precision test at triangle edges
if (sizeof(Float) == sizeof(float) &&
(e0 == 0.0f || e1 == 0.0f || e2 == 0.0f)) {
double p2txp1ty = (double)p2t.x * (double)p1t.y;
double p2typ1tx = (double)p2t.y * (double)p1t.x;
e0 = (float)(p2typ1tx - p2txp1ty);
double p0txp2ty = (double)p0t.x * (double)p2t.y;
double p0typ2tx = (double)p0t.y * (double)p2t.x;
e1 = (float)(p0typ2tx - p0txp2ty);
double p1txp0ty = (double)p1t.x * (double)p0t.y;
double p1typ0tx = (double)p1t.y * (double)p0t.x;
e2 = (float)(p1typ0tx - p1txp0ty);
}
// Perform triangle edge and determinant tests
if ((e0 < 0 || e1 < 0 || e2 < 0) && (e0 > 0 || e1 > 0 || e2 > 0))
return false;
Float det = e0 + e1 + e2;
if (det == 0) return false;
// Compute scaled hit distance to triangle and test against ray $t$ range
p0t.z *= Sz;
p1t.z *= Sz;
p2t.z *= Sz;
Float tScaled = e0 * p0t.z + e1 * p1t.z + e2 * p2t.z;
if (det < 0 && (tScaled >= 0 || tScaled < ray.tMax * det))
return false;
else if (det > 0 && (tScaled <= 0 || tScaled > ray.tMax * det))
return false;
// Compute barycentric coordinates and $t$ value for triangle intersection
Float invDet = 1 / det;
Float b0 = e0 * invDet;
Float b1 = e1 * invDet;
Float b2 = e2 * invDet;
Float t = tScaled * invDet;
// Ensure that computed triangle $t$ is conservatively greater than zero
// Compute $\delta_z$ term for triangle $t$ error bounds
Float maxZt = MaxComponent(Abs(Vector3f(p0t.z, p1t.z, p2t.z)));
Float deltaZ = gamma(3) * maxZt;
// Compute $\delta_x$ and $\delta_y$ terms for triangle $t$ error bounds
Float maxXt = MaxComponent(Abs(Vector3f(p0t.x, p1t.x, p2t.x)));
Float maxYt = MaxComponent(Abs(Vector3f(p0t.y, p1t.y, p2t.y)));
Float deltaX = gamma(5) * (maxXt + maxZt);
Float deltaY = gamma(5) * (maxYt + maxZt);
// Compute $\delta_e$ term for triangle $t$ error bounds
Float deltaE =
2 * (gamma(2) * maxXt * maxYt + deltaY * maxXt + deltaX * maxYt);
// Compute $\delta_t$ term for triangle $t$ error bounds and check _t_
Float maxE = MaxComponent(Abs(Vector3f(e0, e1, e2)));
Float deltaT = 3 *
(gamma(3) * maxE * maxZt + deltaE * maxZt + deltaZ * maxE) *
std::abs(invDet);
if (t <= deltaT) return false;
// Compute triangle partial derivatives
Vector3f dpdu, dpdv;
Point2f uv[3];
GetUVs(uv);
// Compute deltas for triangle partial derivatives
Vector2f duv02 = uv[0] - uv[2], duv12 = uv[1] - uv[2];
Vector3f dp02 = p0 - p2, dp12 = p1 - p2;
Float determinant = duv02[0] * duv12[1] - duv02[1] * duv12[0];
if (determinant == 0) {
// Handle zero determinant for triangle partial derivative matrix
CoordinateSystem(Normalize(Cross(p2 - p0, p1 - p0)), &dpdu, &dpdv);
} else {
Float invdet = 1 / determinant;
dpdu = (duv12[1] * dp02 - duv02[1] * dp12) * invdet;
dpdv = (-duv12[0] * dp02 + duv02[0] * dp12) * invdet;
}
// Compute error bounds for triangle intersection
Float xAbsSum =
(std::abs(b0 * p0.x) + std::abs(b1 * p1.x) + std::abs(b2 * p2.x));
Float yAbsSum =
(std::abs(b0 * p0.y) + std::abs(b1 * p1.y) + std::abs(b2 * p2.y));
Float zAbsSum =
(std::abs(b0 * p0.z) + std::abs(b1 * p1.z) + std::abs(b2 * p2.z));
Vector3f pError = gamma(7) * Vector3f(xAbsSum, yAbsSum, zAbsSum);
// Interpolate $(u,v)$ parametric coordinates and hit point
Point3f pHit = b0 * p0 + b1 * p1 + b2 * p2;
Point2f uvHit = b0 * uv[0] + b1 * uv[1] + b2 * uv[2];
// Test intersection against alpha texture, if present
if (testAlphaTexture && mesh->alphaMask) {
SurfaceInteraction isectLocal(pHit, Vector3f(0, 0, 0), uvHit, -ray.d,
dpdu, dpdv, Normal3f(0, 0, 0),
Normal3f(0, 0, 0), ray.time, this);
if (mesh->alphaMask->Evaluate(isectLocal) == 0) return false;
}
// Fill in _SurfaceInteraction_ from triangle hit
*isect = SurfaceInteraction(pHit, pError, uvHit, -ray.d, dpdu, dpdv,
Normal3f(0, 0, 0), Normal3f(0, 0, 0), ray.time,
this);
// Override surface normal in _isect_ for triangle
isect->n = isect->shading.n = Normal3f(Normalize(Cross(dp02, dp12)));
if (mesh->n || mesh->s) {
// Initialize _Triangle_ shading geometry
// Compute shading normal _ns_ for triangle
Normal3f ns;
if (mesh->n) {
ns = (b0 * mesh->n[v[0]] + b1 * mesh->n[v[1]] +
b2 * mesh->n[v[2]]);
if (ns.LengthSquared() > 0)
ns = Normalize(ns);
else
ns = isect->n;
} else
ns = isect->n;
// Compute shading tangent _ss_ for triangle
Vector3f ss;
if (mesh->s) {
ss = (b0 * mesh->s[v[0]] + b1 * mesh->s[v[1]] +
b2 * mesh->s[v[2]]);
if (ss.LengthSquared() > 0)
ss = Normalize(ss);
else
ss = Normalize(isect->dpdu);
}
else
ss = Normalize(isect->dpdu);
// Compute shading bitangent _ts_ for triangle and adjust _ss_
Vector3f ts = Cross(ss, ns);
if (ts.LengthSquared() > 0.f) {
ts = Normalize(ts);
ss = Cross(ts, ns);
} else
CoordinateSystem((Vector3f)ns, &ss, &ts);
// Compute $\dndu$ and $\dndv$ for triangle shading geometry
Normal3f dndu, dndv;
if (mesh->n) {
// Compute deltas for triangle partial derivatives of normal
Vector2f duv02 = uv[0] - uv[2];
Vector2f duv12 = uv[1] - uv[2];
Normal3f dn1 = mesh->n[v[0]] - mesh->n[v[2]];
Normal3f dn2 = mesh->n[v[1]] - mesh->n[v[2]];
Float determinant = duv02[0] * duv12[1] - duv02[1] * duv12[0];
if (determinant == 0)
dndu = dndv = Normal3f(0, 0, 0);
else {
Float invDet = 1 / determinant;
dndu = (duv12[1] * dn1 - duv02[1] * dn2) * invDet;
dndv = (-duv12[0] * dn1 + duv02[0] * dn2) * invDet;
}
} else
dndu = dndv = Normal3f(0, 0, 0);
isect->SetShadingGeometry(ss, ts, dndu, dndv, true);
}
// Ensure correct orientation of the geometric normal
if (mesh->n)
isect->n = Faceforward(isect->n, isect->shading.n);
else if (reverseOrientation ^ transformSwapsHandedness)
isect->n = isect->shading.n = -isect->n;
*tHit = t;
++nHits;
return true;
}
