Re: [Update REQ 5235]: lights in geomview and Mathematica

["Stuart Levy" <slevy>]

First: I don't know how Mathematica computes its shading.  I think it's
undocumented.

Second: there's a fair, though far from perfect, match between Mathematica
and Geomview lighting if you use your lighting model, but set the specular
reflectance ("ks" in the initialization file, or see the Materials panel)
to zero, and the ambient reflectance ("ka") to about .1.