public virtual Spectrum Rho(int numSamples, float[] samples1, float[] samples2)
{
Spectrum r = Spectrum.CreateBlack();
for (int i = 0; i < numSamples; ++i)
{
// Estimate one term of $\rho_\roman{hh}$
Vector wo, wi;
wo = MonteCarloUtilities.UniformSampleHemisphere(samples1[2 * i], samples1[2 * i + 1]);
float pdf_o = MathUtility.InvTwoPi, pdf_i;
Spectrum f = SampleF(wo, out wi, samples2[2 * i], samples2[2 * i + 1], out pdf_i);
if (pdf_i > 0.0f)
{
r += f * ReflectionUtilities.AbsCosTheta(ref wi) * ReflectionUtilities.AbsCosTheta(ref wo) / (pdf_o * pdf_i);
}
}
return(r / (MathUtility.Pi * numSamples));
}
public override Spectrum SampleL(Scene scene, LightSample ls, float u1, float u2, float time, out Ray ray, out Normal ns, out float pdf)
{
// Choose point on disk oriented toward infinite light direction
Point worldCenter;
float worldRadius;
scene.WorldBound.BoundingSphere(out worldCenter, out worldRadius);
Vector v1, v2;
Vector.CoordinateSystem(_direction, out v1, out v2);
float d1, d2;
MonteCarloUtilities.ConcentricSampleDisk(ls.UPos0, ls.UPos1, out d1, out d2);
Point Pdisk = worldCenter + worldRadius * (d1 * v1 + d2 * v2);
// Set ray origin and direction for infinite light ray
ray = new Ray(Pdisk + worldRadius * _direction, -_direction, 0.0f, float.PositiveInfinity, time);
ns = (Normal)ray.Direction;
pdf = 1.0f / (MathUtility.Pi * worldRadius * worldRadius);
return(_radiance);
}
public override Point Sample(Point p, float u1, float u2, out Normal ns)
{
// Compute coordinate system for sphere sampling
Point Pcenter = ObjectToWorld.TransformPoint(Point.Zero);
Vector wc = Vector.Normalize(Pcenter - p);
Vector wcX, wcY;
Vector.CoordinateSystem(wc, out wcX, out wcY);
// Sample uniformly on sphere if $\pt{}$ is inside it
if (Point.DistanceSquared(p, Pcenter) - _radius * _radius < 1e-4f)
{
return(Sample(u1, u2, out ns));
}
// Sample sphere uniformly inside subtended cone
float sinThetaMax2 = _radius * _radius / Point.DistanceSquared(p, Pcenter);
float cosThetaMax = MathUtility.Sqrt(Math.Max(0.0f, 1.0f - sinThetaMax2));
DifferentialGeometry dgSphere;
float thit, rayEpsilon;
Point ps;
Ray r = new Ray(p, MonteCarloUtilities.UniformSampleCone(u1, u2, cosThetaMax, ref wcX, ref wcY, ref wc),
1e-3f);
if (!TryIntersect(r, out thit, out rayEpsilon, out dgSphere))
{
thit = Vector.Dot(Pcenter - p, Vector.Normalize(r.Direction));
}
ps = r.Evaluate(thit);
ns = (Normal)Vector.Normalize(ps - Pcenter);
if (ReverseOrientation)
{
ns *= -1.0f;
}
return(ps);
}
