Re: IR Onyx2 which rastermanager ?

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Rob Jenkins (robj++at++quid)
Tue, 17 Jun 1997 12:46:11 -0700

On Jun 17, 2:24pm, David Nouls wrote:
> Subject: IR Onyx2 which rastermanager ?
> Hello,
>
> We need to have Multisampling on an Onyx2 with IR at Full Overscan PAL
> resolution.
> How many and which rastermanagers do we need for this ? What are the
> differences between RM6, RM7 and RM8 ?
>
> /)avid
> --
> This sig has been *CENSORED*
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>-- End of excerpt from David Nouls

You can use ircombine to work out how deep your pixels can be ( run on any
machine, just specify target HW - see ircombine user guide ), set up your vof
and see how deep you pixels are: small, medium, large etc ( 256, 512, and 1024
bits and so on ). I think you'd get at least 4 samples at PAL res with 1 RM6.
An example of working this out by hand is, ( once you know pixel depth ):

1.Estimate the number of bits of framebuffer memory required for the
previously-chosen Visual.
          eg.
              32 bits for pixel tag word
            + 30 bits for RGB10 front buffer
            + 30 bits for RGB10 back buffer
            + 4 samples *
               ( 24 bits for RGB8 color
               + 23 bits for Z
               + 1 bit for stencil )
            = 284 bits

RM6 supports pixel depths of 256, 512, and 1024 bits. Round up the number of
bits to the closest depth. eg. 284 rounds up to 512 so if you had medium pixels
you could have RGB10 + 4 samples + 23 bit Z + 1 stencil

There's more to this if you need to think about fill rate etc, if you already
have a machine ( as opposed to working out what HW you need to buy ) then the
easiest thing would be to load your vof with ircombine then run 'findvis' on
the machine and look at the visuals available with multisamples, if you don't
see enough samples ( in a visual that has the other things you need too ) then
you need more RM.

I *think* this is right:

RM6 is Onyx RM, can be 16 or 64MB
RM7 is Onyx2 RM, like RM6 just laid out differently, can be 16 or 64 MB
RM8 is Onyx2 'Reality' RM, it's an RM7 with it's wings clipped, it's cheaper
and has up to 4 multisamples at reduced performance, similar non-multisample
performance, shallower max pixel config.

You'd be looking at RM 7s then.

Cheers
Rob

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