I can't get my shadow pass (alpha) to show up through refractive materials ... I really need to use it for compositing.
UseBackgroundShader refracted through a Phong
UseBackgroundShader refracted through mia_material
mip_matte_shadow refracted through mia_material
I've set all the trace depths for shadows and refractions up high, enabled "pass custom alpha" in r/globals, and checked "propagate alpha" in the mia_material (glass geometry between camera and shadowed object). All i seem to get is either solid white alpha (of the entire geometry), or nothing at all.
I checked master_zap's blog, djx's blog, and the mental images production shader manual, and everything works really well ... it's just getting these passes to distort through refractive geometry that I can't figure out ...