I have surface with perturbed normals(smooth shaded or perturbed with normal map) and I want to evaluate BRDF to get reflected ray.
There is a probability that angle between reflected ray direction and face normal may be greater then π/2.
In this case I'm using rejection sampling to avoid this problem.
I'm generating brdf proportional reflected rays until reflected ray isn't directed as desired. It works correctly but dramatically decreases performance.
Any suggestions will be helpful
