Moshe Nissim (moshe++at++orad.co.il)
Tue, 21 Oct 1997 12:32:05 +0300
>
> This sounds right, Reality has reduced framebuffer capacity compared to iR ( it
> will only do 4 multisamples max ).
>
> Reality is essentially an iR with it's wings clipped ( hence the price
> difference :-) ), there's summary info on:
> http://www.sgi.com/Products/hardware/graphics/products/Onyx2Reality.html
>
> Onyx2 Reality
> Hot New Graphics at an Accessible Price
>
> The Onyx2 Reality deskside system has one to four
> 1MB cache MIPSŪ R10000 processors, 64MB to
> 2GB of Memory, and a single graphics pipeline with
> one or two Reality Raster Managers (RM).
>
> 5.5M Polygons/sec
> 4-sample antialiasing
> 2 RM capacity
> 40MB Frame Buffer each
> 16 or 64MB of Texture Memory
> 1-4 180MHz 1MB Cache R10000 CPU's
> 64MB-2GB RAM
> 1-5 3.5" Ultra SCSI discs (4.5, 9.1GB)
> Integrated Audio and Standard CDROM
> 4 I/O Slots (Optional PCI)
> 20" Monitor
>
> I hope this isn't too different from what you expected when you bought the
> machine !
>
It is quite different from what I expected.
I knew the fb size is 40 Mb.
I knew it has reduced fill-rate.
I knew it has reduced texture fill-rate.
I knew it has only 4 samples.
But in the above spec there is no mention of a limit on pixel depth that
is
above the normal fb memory limitations.
I could'nt get "large" pixels even when I got down to tiny framebuffer
resolutions and 2x or 4x RMs.
But now I realize the problem is even deeper.
Medium pixels are 512 bits.
This should be enough for rgba + 4 samples + z + double-buffer:
(RGBA+Z)*MS + RGBA = (4*12+23)*4 + 4*12 = 332
which is much smaller than 512.
Indeed, when I run
findvis 'rgba && ms && z && db'
on an Onyx1 InfiniteReality, configured for medium pixels (as indicated
by
/usr/gfx/gfxinfo), I get many matching visuals, including even stereo
and accumulation.
When I run the same findvis on an Onyx2 Reality configured for medium
pixels,
I get no visuals at all.
Even when lifting the z-buffer and double-buffer requirements (findvis
'rgba && ms')
I get no visuals.
What is going on in there?
Bye,
Moshe Nissim
Orad Hi-Tec Systems
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