Here are implementations of the paper entiled "Position-free Multiple-bounce Computations for Smith Microfacet BSDFs" and paper entiled "Multiple-bounce Smith Microfacet BRDFs using the Invariance Principle".
Here are implementations of the paper entiled "Position-free Multiple-bounce Computations for Smith Microfacet BSDFs" and paper entiled "Multiple-bounce Smith Microfacet BRDFs using the Invariance Principle".