Timothy Moore (moore++at++WOLFENET.com)
Wed, 16 Oct 1996 10:43:05 -0700 (PDT)
Thanks to all who responded to my problem.
Especially, thanks to Tim Moore for the advice (see included message
below). It worked, sort of...
After turning on the two-sided light model, I now get polygons illuminated
on both sides. However, the back sides are not colored, but are rendered
in shades of gray. Any more advice Tim?
Oh yeah, I forgot the other thing :) You need a backface material too
e.g.:
pfGStateAttr (gstate, PFSTATE_BACKMTL, material);
Generally you would want the front and back materials to be the same.
If you aren't creating GeoSets and GeoStates "by hand", there should
be an option in your modelling tool to do the right thing for back
faces.
Note that in IrisGL the color mode for the backface material can't be
changed from LMC_COLOR (or, in Performer, PFMTL_CMODE_COLOR). Most
Performer databases are defined with PFMTL_CMODE_AD so the lighting
may look anomalous.
Tim
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