Re: advice on using Performer (OpenGL Optimizer?)

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David Weller (dweller++at++rivatech.com)
Fri, 12 Sep 1997 08:53:15 -0500 (CDT)


> > > > I am planning to write a walkthrough application on top of Performer
> > > > and would like some advice on the issues I am facing. I will be using
> > > > an SGI Octane with two R10000 processors.
> > > > [deletia]
> >
> > The basic motivation of the application is to do occlusion culling in
> > software.Hence, rather than rendering *all* triangles in the view
> > frustum using the Z-buffer, I want to determine which are (partially)
> > visible using the BSP and render only these.
>
> [deletia of some of Remi's comments]
>
> That is Occlusion culling, which BSP does not provide naturally, and that
> would be a good win if this is the kind of database you are walking through.
>

Perhaps slightly off-topic, but that was the primary focus of OpenGL
Optimizer, was it not? Walkthru-type applications need occlusion
culling, and that's exactly what OpenGL Optimizer does. Of course,
the count of available database loaders, as far as I can tell, is
currently at "2" :-) (Somebody correct me, PLEASE!)

Which brings me to another small issue, which is that there doesn't
appear to be very many good guidelines to help developers decide where
the greatest advantage per application comes from (Performer v. OpenGL
Optimizer). Certainly from my perspective, I'm going to get better
performance using Performer for things like flight simulation. But if
I have a customer that wants me to deliver an application of, say, a
new selection of homes, I'm faced with a new set of decisions. SGI
press releases say, "This is great for CAD/CAM/CAE stuff!" but many of
us work in the fuzzy, gray areas (or in both domains :-).

IMHO, this is a FAQ that belongs in both the Performer and OpenGL
Optimizer FAQs.

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