Re: Configuring framebuffer.

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Angus Dorbie (dorbie++at++sgi.com)
Fri, 24 Sep 1999 18:38:22 -0700

P.S.
Bear in mind you could use multisample masking to combine multiple
passes in the framebuffer instead of the accumulation buffer. This would
be faster and could help with the split image target ranging I'm
guessing you are trying to perform based on other periscope sims I've
worked on.

Also why RGBA12? Do you need this for 8 sample aa or destination alpha?

Cheers,Angus.

Angus Dorbie wrote:
>
> Create two channels, one for near and one for far. Draw the near channel
> after the far channel after clearing the depth buffer and set it's far
> just a little further that the far channels near. This will allow you to
> push the near clip a lot further out on the distant channel and just add
> a few objects and mayve the near ocean skin to the near channel.
>
> CHeers,Angus.
>
> phowe++at++csc.com wrote:
> >
> > Hi,
> >
> > We are writing a periscope simulation and are currently having problems with Z
> > fighting.
> > We are running on an InfiniteReality2 with 1 RM9 Raster Manager and are drawing
> > to
> > two displays which both use the same area of the framebuffer ( one virtual
> > binoculars
> > 1280x1024 180Hz field sequential, the other is a standard monitor 1280x1024 60Hz
> > ).
> > For the application we need to use an accumulation buffer. The visual that fits
> > our
> > needs best is the following ( from findvis). We are using Medium pixel depth
> >
> > 0x6b, RGBA 12/12/12/12, db, Z 16, accum 25/25/25/25, samples 4
> >
> > Unfortunately that only gives us 16 bits for the Z buffer, and due to the
> > application
> > we need to have the near clip plane at 1m at the far clip plane at 50,000m.
> >
> > Is there a way we can change the framebuffer configuration to reduce the number
> > of
> > bits per component in the accumulation buffer and use them to increase the bits
> > in the
> > Z buffer?
> >
> > Any help would be greatly appreciated.
> >
> > Peter
> >
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>
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-- 
"One of the best-known folk theorems of software engineering is that
60% to 75% of conventional software projects are either never
completed or rejected by their intended users. If that range is
anywhere near true (and I've never met a manager of any experience
who disputes it) then more projects than not are being aimed at goals
which are either (a) not realistically attainable, or (b) just plain
wrong."
                 Eric S. Raymond - The Cathedral and The Bazaar


For advanced 3D graphics Performer + OpenGL based examples and tutors:
http://www.dorbie.com/

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