Coplanar Planes

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Benito Graniela (graniela++at++vsl.ist.ucf.edu)
Thu, 16 Feb 1995 08:43:38 -0500


The SGI performer Frequently Asked Questions (FAQ) answer to the
coplanar polygons problem reads;

------------------------------

Subject: + -25- Coplanar Polygons & pfDecal on certain platforms
Date: 8 Apr 94 00:00:01 EST

pfDecal works only on machines that support the stencil or
displacepolygon command. The default decaling mode for PFDECAL_BASE
now uses displacepolygon instead of stencil. This can significantly
improve rendering performance but can result in visual anomalies
where layer polygons incorrectly "poke" through other geometry. If
you wish the old behavior then specify the PFDECAL_BASE_HIGH_QUALITY
token.

------------------------------

What can you do to solve this problem on a Indigo Extreme that can not
support stencil or displacepolygon commands?

We have roads over terrain that flash constantly, even when separated from
the terrain by 0.1 meters. We believe this is a Z-buffer priority problem, can
anybody elaborate! The best solution that we can come out with is to
"stitch" the roads in, in other word replacing the terrain polygons with
road polygons. This is a very time consuming task and we are looking for
other solutions to this problem.

thanks
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Benito Graniela University of Central Florida
Visual Systems Lab Institute for Simulation & Training
(407) 658-5075 3280 Progress Drive
bgraniela++at++vsl.ist.ucf.edu Orlando, FL 32806-0544
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