Re: PBuffer on Onyx2 Reality

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reiners++at++igd.fhg.de
Fri, 5 Mar 1999 10:35:19 +0100 (MET)

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On Mar 4, 7:37pm, Christian Ernst wrote:
> Subject: PBuffer on Onyx2 Reality
> Hi all,
>
> I'm trying to use the SGI PBuffers on different machines. I have read
> the old messages from Dec 98, so that I know about the "Bad Alloc "
> problem.
> When I get the fbconfig list, I'm trying all configs till I'm
successful
> in
> creating a pbuffer.
> This works perfect on an Octain, an Indigo2 and an Onyx. But on an
Onyx2
> Reality I get no suitable pbuffer. On this machine I can only
allocate
> pbuffers with no depth buffer and R>=10/G>=10/B>=10, or with depth
> buffer
> and R>=10/G=0/B=0.
>
>-- End of excerpt from Christian Ernst

Apparently iR/Reality won't give you a usable pbuffer if you only have
small pixel depth. When we reduced the managed area so that we got
medium pixel depth a usable configuration became available.

It's a bit strange, as AFAIK small pixel depth is 128 bit/pixel and
Impact has, again AFAIK, 3*36=108 bit/pixel. There are probably some
other magic constraints about blocking different groups of bits, but I
would have expected more.

As you only have a Reality you have a problem there, as even 1024x768
will only get you small pixel depth. You would have to go down to
800x600 or cook up your format in the area of ~960x680. Not a pretty
sight in any case, but good enough for testing.

But then again I just might be wrong and there is a magic button that
will bring us eternal peace and infinite pbuffers. Can anybody tell me
which one it is?

Dirk

--
-- Dirk Reiners              reiners++at++igd.fhg.de, Dirk.Reiners++at++gmx.net 
-- IGD - A4                            http://www.igd.fhg.de/~reiners
-- Rundeturmstrasse 6
-- D-64283 Darmstadt                  All standard disclaimers apply. 
-- Truth is stranger than fiction because fiction has to make sense.

Next message: Liu Xiaoyan: "buffer requirment for glPolygonOffsetEXT"
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