Re: [info-performer] multipass pfDraw and MP systems

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From: Stace Peterson (stacep++at++sgi.com)
Date: 02/17/2005 15:09:37

Georgios,

The way we have done this for the pfCity demo was to separate the
geometry into bins, and through use of pfOverride and pfDrawBin calls,
only render the geometry which is used for that pass. Just as you have
surmised, trying to change the traversal masks in the draw process has
no effect. Using bins is a bit more effort than simply changing the
masks, but provides the control you'll need at significantly less cost
than trying to perform your own mask checking and traversal. Check the
man page for pfChannel for the details about creating and setting up
bins.

Stace

Georgios Papaioannou wrote:
>
> Hi everybody,
>
> I am trying to rewrite a Performer application so that it fully utilises the
> PFMP_APP_CULL_DRAW concurrent process configuration AND have two subsequent
> pfDraw() passes for each channel (one in the post-draw phase, 4 channels)
> with different draw traversal masks for each pass (in order to implement
> selective volume shadow casting on geometry). Unfortunately, as the manual
> states, after the cull stage this configuration is producing display lists
> and no matter what masks I set in between the calls to pfDraw(), I get the
> same image drawn as in the first pass. When I switch to PFMP_APP_CULLDRAW
> configuration, this fixes the problem as drawing is done in immediate mode,
> but this has a severe impact on our 8-processor Onyx2 framerate.
>
> Can anybody come up with a suggestion about this? The only other option I
> can think of is to write my version of pfDraw() and perform mask checking
> and draw traversal on my own, but I guess this is not a very elegant
> solution!
>
> Thanks for your time.
>
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-- 
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Stace Peterson                                      stacep++at++sgi.com
Silicon Graphics, Inc.                              (650) 933-2323

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