I have been using radiance to model textured glass surfaces in order to obtain the corresponding BSDF with success, but I am now tackling a case for which I have not been able to find a suitable solution in Radiance: coated glass surface. In this case, I cannot use the dielectric material anymore, as the material ensures both the refraction and reflection of the rays (which I want), but also the amount of reflection according to Fresnel laws, which is modified in that case. I cannot use BRTDfunc either, as it advised for coated glass in general, as in that case I will indeed be able to specify the reflection coefficients as a function of angle from inside and outside the material, but I will loose the refraction part, which is necessary to retrieve the haze induced by textured glass of course.
My ideal need would be to keep the behaviour proposed by the dielectric material, but be able to inject some other law than the Fresnel one for the reflection as a function of angle, either analytic or with tabulated data. Is there a way to do such a thing with Radiance?