Re: Q: pfLayerModes

New Message Reply Date view Thread view Subject view Author view

Marcus Barnes (marcus++at++multigen.com)
Fri, 20 Jun 1997 19:33:50 -0700

On Jun 20, 7:39am, Steve Baker wrote:
> marcus wrote:
> >
> > Coplanarity tolerance can be a problem for STENCIL. Performer 2.x requires
a
> > much tighter (truer) tolerance than 1.x did.
>
> ...I find this hard to believe. Isn't Z buffer testing disabled
> when the layer polygon is rendered in STENCIL mode? I thought that was
> the entire point of using STENCIL.

Yes, but the base geometry defines the Z buffer value for the layer geometry.
Notice that STENCIL mode is the only mode that _requires_ coplanarity
(man pfdecal).

> That being the case, surely the tolerance is unimportant. So long as the
> layered polygons appear to be entirely inside the base polys, there should
> be no problem.

Angus pinged me on this in his earlier reply and I followed up with the history
behind my initial statement. I think that the tighter 2.x displacement
tolerance is not an issue with STENCIL, but true coplanarity is ...

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       +
=======================================================================
List Archives, FAQ, FTP:  http://www.sgi.com/Technology/Performer/
            Submissions:  info-performer++at++sgi.com
        Admin. requests:  info-performer-request++at++sgi.com

New Message Reply Date view Thread view Subject view Author view

This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:55:29 PDT

This message has been cleansed for anti-spam protection. Replace '++at++' in any mail addresses with the '@' symbol.