Brian Sharpe

I think the sqrtPiOver8 factor might be an internal BSDF implementation detail, rather than something that should be done externally. For example, MDL already applies this factor internally. https://github.com/NVIDIA/MDL-SDK/blob/master/src/mdl/jit/libbsdf/libbsdf_hair.h#L174

> MDL applies the π/8 factor for both longitudinal and azimuthal roughness I don't think it does. The MDL hair_prepare_roughness() function in that github link I posted only applies it...

I think might need some more changes. In its current form, someone can't tweak the TT and TRT scaling factors. So I'm thinking of two potential changes to accommodate this....

In PLY, these 3 are typically stored in an awkward machine-learning format (rather than more standard CG formats) - opacity: in sigmoid form (graphics would prefer not sigmoid) - scale:...