public void AbsDotProduct()
{
var a = new Normal(1, 2, 3);
var b = new Normal(2, 3, 4);
Normal.AbsDot(a, b).Should().BeApproximately(20f, 0.00001f);
b = new Normal(-2, 3, -4);
Normal.Dot(a, b).Should().BeApproximately(-8f, 0.00001f);
Normal.AbsDot(a, b).Should().BeApproximately(8f, 0.00001f);
}
public virtual float Pdf(Point p, Vector wi)
{
// Intersect sample ray with area light geometry
var ray = new Ray(p, wi, 1e-3f);
ray.Depth = -1; // temporary hack to ignore alpha mask
float thit, rayEpsilon;
DifferentialGeometry dgLight;
if (!TryIntersect(ray, out thit, out rayEpsilon, out dgLight))
{
return(0.0f);
}
// Convert light sample weight to solid angle measure
float pdf = Point.DistanceSquared(p, ray.Evaluate(thit)) / (Normal.AbsDot(dgLight.Normal, -wi) * Area);
if (float.IsInfinity(pdf))
{
pdf = 0.0f;
}
return(pdf);
}