Spectrum InfiniteAreaLight::Sample_Li(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
// Find $(u,v)$ sample coordinates in infinite light texture
Float mapPdf;
Point2f uv = distribution->SampleContinuous(u, &mapPdf);
uv[0] -= (Float)0.5 / Lmap->Width();
uv[1] -= (Float)0.5 / Lmap->Height();
if (mapPdf == 0) return Spectrum(0.f);
// Convert infinite light sample point to direction
Float theta = uv[1] * Pi, phi = uv[0] * 2 * Pi;
Float cosTheta = std::cos(theta), sinTheta = std::sin(theta);
Float sinPhi = std::sin(phi), cosPhi = std::cos(phi);
*wi =
LightToWorld(Vector3f(sinTheta * cosPhi, sinTheta * sinPhi, cosTheta));
// Compute PDF for sampled infinite light direction
*pdf = mapPdf / (2 * Pi * Pi * sinTheta);
if (sinTheta == 0) *pdf = 0;
// Return radiance value for infinite light direction
*vis = VisibilityTester(ref, Interaction(ref.p + *wi * (2 * worldRadius),
ref.time, mediumInterface));
return Spectrum(Lmap->Lookup(uv), SpectrumType::Illuminant);
}
Spectrum SpotLight::Sample_Li(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
*wi = Normalize(pLight - ref.p);
*pdf = 1.f;
*vis = VisibilityTester(ref, Interaction(pLight, ref.time, medium));
return intensity * Falloff(-*wi) / DistanceSquared(pLight, ref.p);
}
// GonioPhotometricLight Method Definitions
Spectrum GonioPhotometricLight::Sample_L(const Interaction &ref,
const Point2f &sample, Vector3f *wi,
Float *pdf,
VisibilityTester *vis) const {
*wi = Normalize(pLight - ref.p);
*pdf = 1.f;
*vis = VisibilityTester(ref, Interaction(pLight, ref.time, medium));
return intensity * Scale(-*wi) / DistanceSquared(pLight, ref.p);
}
Spectrum DistantLight::Sample_L(const Interaction &ref, const Point2f &sample,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
*wi = wLight;
*pdf = 1.f;
Point3f pOutside = ref.p + wLight * (2 * worldRadius);
*vis = VisibilityTester(ref, Interaction(pOutside, ref.time, medium));
return L;
}
Spectrum ProjectionLight::Sample_Li(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
ProfilePhase _(Prof::LightSample);
*wi = Normalize(pLight - ref.p);
*pdf = 1;
*vis =
VisibilityTester(ref, Interaction(pLight, ref.time, mediumInterface));
return I * Projection(-*wi) / DistanceSquared(pLight, ref.p);
}
Spectrum DiffuseAreaLight::Sample_Li(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
Interaction pShape = shape->Sample(ref, u);
pShape.mediumInterface = mediumInterface;
*wi = Normalize(pShape.p - ref.p);
*pdf = shape->Pdf(ref, *wi);
*vis = VisibilityTester(ref, pShape);
return L(pShape, -*wi);
}
Spectrum DiffuseAreaLight::Sample_Li(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
ProfilePhase _(Prof::LightSample);
Interaction pShape = shape->Sample(ref, u, pdf);
pShape.mediumInterface = mediumInterface;
if (*pdf == 0 || (pShape.p - ref.p).LengthSquared() == 0) {
*pdf = 0;
return 0.f;
}
*wi = Normalize(pShape.p - ref.p);
*vis = VisibilityTester(ref, pShape);
return L(pShape, -*wi);
}
Spectrum PerspectiveCamera::Sample_Wi(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
Point2f *pRaster,
VisibilityTester *vis) const {
// Uniformly sample a lens interaction _lensIntr_
Point2f pLens = lensRadius * ConcentricSampleDisk(u);
Point3f pLensWorld = CameraToWorld(ref.time, Point3f(pLens.x, pLens.y, 0));
Interaction lensIntr(pLensWorld, ref.time, medium);
lensIntr.n = Normal3f(CameraToWorld(ref.time, Vector3f(0, 0, 1)));
// Populate arguments and compute the importance value
*vis = VisibilityTester(ref, lensIntr);
*wi = lensIntr.p - ref.p;
Float dist = wi->Length();
*wi /= dist;
// Compute PDF for importance arriving at _ref_
// Compute lens area of perspective camera
Float lensArea = lensRadius != 0 ? (Pi * lensRadius * lensRadius) : 1;
*pdf = (dist * dist) / (AbsDot(lensIntr.n, *wi) * lensArea);
return We(lensIntr, -*wi, pRaster);
}
