Function SampleHG

src/luxrays/utils/mc.cpp:172–186

}

Vector SampleHG(const Vector &w, float g, const float u1, const float u2) {
	float costheta;
	if (fabsf(g) < 1e-3f)
		costheta = 1.f - 2.f * u1;
	else {
		// NOTE - lordcrc - Bugfix, pbrt tracker id 0000082: bug in SampleHG
		const float sqrTerm = (1.f - g * g) / (1.f - g + 2.f * g * u1);
		costheta = (1.f + g * g - sqrTerm * sqrTerm) / (2.f * g);
	}
	const float sintheta = sqrtf(Max(0.f, 1.f - costheta * costheta));
	const float phi = 2.f * M_PI * u2;
	Vector v1, v2;
	CoordinateSystem(w, &v1, &v2);
	return SphericalDirection(sintheta, costheta, phi, v1, v2, w);
}

float PhaseHG(const Vector &w, const Vector &wp, float g) {
	const float costheta = Dot(w, wp);