Re: Q: pfLayerModes

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Marcus Barnes (marcus++at++multigen.com)
Thu, 12 Jun 1997 13:15:31 -0700


On Jun 11, 12:43pm, Mark Baranowski wrote:
>
> Machine Details:
> Onyx iR, Irix 6.2 + Patch 1355, Vega 3.0 MP, Performer 2.1 (No
> specific Performer patches that I can see).
>
> PFDECAL_BASE_HIGH_QUALITY solves the Z fighting problem, but *some* of
> the subfaces tend to "poke through" when they should be hidden by
> other parts of the model/scene. Is this is the problem that occurs if
> the subfaces are not coplanar with, or bounded by, the parent face?

Coplanarity tolerance can be a problem for STENCIL. Performer 2.x requires a
much tighter (truer) tolerance than 1.x did. Another conflict has to do with
transparent geometry. Do the problem subfaces have alpha? If so, the draw order
mechanisms of pfDecal and pfChannel::PFSORT_TRANSP_BIN don't always produce the
right results, depending on the eyepoint.

> The problems seem to occur mainly on building models which are
> provided with MultiGen's SmartScene tool, which I imagined would only
> have subfaces which were coplanar and contained within the parent
> face.

The coplanar tolerance may not be "close enough" for Performer.

> I checked some of our own models which exhibit the problem and
> the subfaces *are* coplanar and entirely bounded by the parent
> polygon. Am I missing something?

Tighten the tolerance on your coplanarity check. Use "Edit->Match Vertices" or
"Plant" to to insure coplanarity exactly.

Regards.

--
+ Marcus Barnes, Technical Staff        mailto:marcus++at++multigen.com +
+ Multigen Inc.                         http://www.multigen.com    +
+ 550 S. Winchester Blvd.               phoneto:1-408-556-2654     +
+ Suite 500 San Jose CA 95128           faxto:1-408-261-4102       +
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