LuxRender Materials RoughGlass
From LuxRender Wiki
The Rough Glass material represents a rough dielectric surface. It works well for frosted glass and some kinds of ice.
The index of refraction for the material. This value determines the overall appearance of the material, and should be set according to the material you are trying to simulate
This is the color of light reflected from the surface.
This is the color that light will be filtered to after being transmitted. For perfectly clear glass, set both reflection and transmission colors to 1.0. The color given here will be applied to the material uniformly, you may wish to derive the color from the objects volume instead. (or use the glass2 material, which uses the volume for nearly everything)
Enables chromatic dispersion to be calculated from the Cauchy B value (see below). Setting this to true will enable chromatic dispersion, aka splitting the spectrum into a rainbow of colors. Be warned this is an intensive effect that will greatly increase the number of samples (and photons, if applicable) that are needed!
This is the B value to Cauchy's equation. (The value specified under IOR will be used for n)
This determines how clear the material is by varying the roughness of microfacets. If your exporter uses the exponent to control roughness, higher values are more transparent, with 0 being a matte glass surface. If your exporter uses the direct roughness control, lower values are clearer, with 0 being a perfectly reflective and transmissive surface like the glass and glass2 materials, and .8 being matte. Values between .8 and 1 are an unrealistic "super-matte" and should be avoided.