Re: reflecting GeoSets causes shading to malfunciton (fwd)

Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Fri, 7 Feb 1997 19:22:44 +0000

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The normals will also be transformed by the model matrix, but
vertex winding will be reversed, as already posted.
With two sided lighting the reversed normal and back face material
will be used. If the backface material is the same as the frontface
material and two sided lighting is on then reversing the normal
could fix the problem.

The three posted fixes so far including yours are:

1) Reverse vertex ordering either in the database or in the GL.
2) Turn off two sided lighting and reverse face _culling_.
3) As you say, reverse surface normals, but you must also ensure
   that back face material == frontface material.

Cheers,
Angus.
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