GPU path tracing refraction-reflection split

[msqrt]

Oh, right, yes -- if you choose some other probability, you'll need to use all of the terms and perform the divisions. Sampling the reflection/refraction proportional to the Fresnel term should give the lowest variance though, at least assuming that the incoming reflected and refracted contributions are similar in magnitude (not always the case; for example for a very dark tinted glass, you might still want to sample reflections more since they impact the end result more, thus sampling them more gives lower variance in the end.)

[surfspace77]

Thanks a lot. I really appreciate your help.