Re: Problem with model flickering in Performer 2.0

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Nathaniel Bletter (nat++at++od.sri.com)
Fri, 20 Sep 1996 15:22:03 -0700

This definitely sounds like a Z-buffer problem with the Ocean below Africa
showing instead of the land polygons. Perhpaps your near and far planes are so
far apart that the Z resolution is not very good. Try moving the near point out
some and moving the far point to the max size of the world if you know that.
Remember it is essentially logarithmic, so a near point of 2 is much much
better than 0.5 say.

On Sep 20, 2:53pm, Gary E Williams wrote:
> Subject: Problem with model flickering in Performer 2.0
> I recently ported a virtual solar system modeler from Performer 1.2 to 2.0.
> I'm now having problems with flickering in many of my models. By
flickering,
> I mean models which have texture maps and models which don't have texture
maps
> have periodic changes of color. For example, Africa and other parts of the
> earth flicker between the approriate land colors and blue (the ocean). That
> model uses a texture map. With another model, a satellite, the colors
flicker
> between what they're supposed to be and other colors. The satellite doesn't
> use texture maps. I've also checked for coplanar polygons, averaged
vertices,
> etc. Coryphaeus has attempted to help me, but the problem seems to be
> Performer related, not a model problem. This conclusion is substantiated by
> the fact that I didn't have these problems in Performer 1.2. The problem is
> magnified as the viewing distance to the model is increased, i.e. up close
the
> flickering isn't too bad or is nonexistent but it gets worse as you move away
> from the model. Some of the models use LOD and some don't. This doesn't
seem
> to have any impact on the problem.
>
> Input from anyone experiencing this type of problem or from anyone who knows
of
> a solution would be greatly appreciated. Does this sound like a Z-Buffer
> problem?
>
> I'm running on an Onyx RE^2 under IRIX 6.2. Thanks.
>
> Gary
>
> --
> *************************************************************
>
> GARY E. WILLIAMS, Capt, USAF
> MS Student: Modeling & Simulation
> Air Force Institute of Techonology (AFIT)
>
> gewillia++at++afit.af.mil
> http://www.afit.af.mil/ENGgraphics/people/gewillia/index.html
>
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>
>-- End of excerpt from Gary E Williams

--


Nat Bletter
SRI International
nat++at++od.sri.com
http://os.sri.com/people/nat/
(415) 859-4358
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