Re: advice on using Performer (OpenGL Optimizer?)

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Rob Jenkins (robj++at++quid)
Fri, 12 Sep 1997 10:31:13 -0700

.snip.
> 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!)
>

Optimiser does indeed do clever culling. The Optimiser whitepaper ( link under
the Optimiser web page off www.sgi.com/Technology ) says this about loaders:

"
Reading Files and Database Paging: OpenGL Optimizer and the scene graph layer
API provide an extensible subsystem for reading and writing design files.
Sample loaders are provided to read Open Inventor files and a highly efficient
binary file format called CSB.
IRIS Performer PFB data files can also be read into OpenGL Optimizer and stored
into the CSB format, providing access to the 40 file formats supported by IRIS
Performer. Adding new loaders is not difficult and there are examples that
demonstrate how this is done.
"

Note - to be clear, the utility 'pfconv' will read any supported PF format, and
write to .pfa, .pfb, .dwb or medit.

> 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.
>

I'm not sure there's a clear general answer except to get detail on each API
and consider any application specifically. There's more Optimiser info under
the web page ( mentioned above ). You're right though, a discussion of relative
merits of the current APIs would be useful. In the future, mixing/matching
features from the various APIs will get easier and avoid this situation.

Cheers
Rob

-- 
________________________________________________________________
Rob Jenkins mailto:robj++at++sgi.com
Silicon Graphics, Mtn View, California, USA
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