Rob Jenkins (robj++at++reading.sgi.com)
Fri, 24 Sep 1999 10:09:45 +0100
I don't have access to an iR with medium pixels right now( can check later I
expect ) so I can't list findvis myself to me sure. In general though the
choice of FB configs you have is set for the pixel depth you have and
limited to only those configs listed by findvis.
I appreciate that the accum buffer numbers look like they're using a lot of
resource but also consider that z buffer and color are duplicate for each
multisample. I don't know for sure but I'm guessing that if you look down
the findvis list you might find a visual with RGBA 10/10/10/0, 23 bit z
buffer and 4 samples. ( note that uses 2 bits for rgb and 12 for no alpha, X
4 for each pixel ) and unless you're doing something like alpha keyed video
blending I doubt you need the alpha channel.
If you can find a bigger Z visual that should help, if it's still not enough
then you need to think about the various approaches discussed previously (
in the archives ) on this list to minimize z fighting, we can get into that
more once the visual issue is sorted.
Cheers
Rob
-----Original Message-----
From: phowe++at++csc.com [mailto:phowe++at++csc.com]
Sent: 24 September 1999 01:38
To: info-performer++at++sgi.com
Subject: Configuring framebuffer.
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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