GL_QUADS and PFGS_QUADS

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Steve Baker (steve++at++mred.bgm.link.com)
Wed, 19 Mar 97 09:38:25 -0500

I noticed a strange thing today, looking at the output of ogldebug,
it looks like the Performer Tmesher take pairs of triangles that share
an edge and turns them into PFGS_QUADS geosets - even if the original
triangles were not mutually planar. This results in a lot of non-planar
PFGS_QUADS geosets.

This would be a bad error were it not for the fact that Performer
doesn't appear to render PFGS_QUADS as GL_QUADS...which is also
a suprising thing.

Is the choice not to render GL_QUADS a performance issue - or is
it for some other reason?

Is it intended that PFGS_QUADS are *allowed* to be non-planar and
consistently split along the 'correct' edge? (This is not mentioned
in the manual anywhere) - or are we merely seeing two bugs that
cancel each other out?

My mother always taught me the "Two wrongs don't make a right" - she
obviously never got into programming!

Steve Baker 817-619-1361 (Vox-Lab)
Hughes Training Inc. 817-619-8776 (Vox-Office/Vox-Mail)
2200 Arlington Downs Road 817-619-4028 (Fax)
Arlington, Texas. TX 76005-6171 Steve++at++MrEd.bgm.link.com (eMail)
http://www.hti.com (external) http://MrEd.bgm.link.com/staff/steve (intranet)
                                http://web2.airmail.net/sjbaker1 (external)

"You can't destroy the Earth - that's where I keep all my stuff!" - The Tick.

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