Guy Russell (guyr++at++thoth.engr.sgi.com)
Mon, 12 Aug 1996 12:14:40 -0700
From: "Guy Russell" <guyr>
Date: Mon, 12 Aug 1996 12:11:53 -0700
To: gedwards++at++reading.sgi.com, guyr++at++cthulhu,
info-performer.sgi.com++at++cordoba.reading.sgi.com,
adorbie++at++cordoba.reading.sgi.com
Subject: Re: Impact tex 4TRAM prob.
On Aug 2, 10:22am, Greg Edwards, SGI UK. wrote:
> Subject: Impact tex 4TRAM prob.
> I have a cust developing on 4TRAM High Impact, loads about 3.5MB of
> texture down using Guy Russell's enahnced pfuTexDownload, which reports
> about 3.5MB texture in use (but about 522 tex pages ?), but gets
> constant texture thrashing (as reported in pfStats). By experiment he
> has found that if texture in model is reduced to 1 MB (as reported by
> pfuDownLoad) thrashing stops.
On Impact graphics using the pfuDownloadTexList for Impacts, the important
metric for texture usage is PAGES not MB. I repeat the number of PAGES used is
what determines whether textures will have to be reloaded each frame. The
limit in the hardware is 256 pages. So, once you are using more than that you
are likely to thrash. If all of your textures are not rendered in the same
scene, you may be able to use more than 256 pages, but you have no way of
knowing when you will texture page.
> All tools seem to be reporting the
> right thing:
> - gfxinfo says 4 TRAM
> - pfuDownLoad says ~ 1MB or 3.5MB
> - Multigen agrees about amount of texture in model.
> - Multigen is using default texture modes.
> - Ditto Perfoemer, so I asume we're getting 16-bit texels.
The default texture component sizes for a 4 TRAM Impact running Performer are
4 component - 4 bits/component - 2 byte texels
3 component - 8 bits/component - 3 byte texels
2 component - 8 bits/component - 2 byte texels
1 component - 8 bits/component - 1 byte texels
You can change this default behavior to use other size textures if you call
pfTexFormat.
>
> The 1MB limit is v. suspicious, is there any way for some part of the
> system to get it wrong and thinkj it only has 1MB TRAM ?
No.
>
> Greg E.
>
> --
> __________________________________________________________________________
> Greg Edwards, Graphics Support/Consulting Group, Silicon Graphics UK Ltd.
> Forum 1, Theale, Reading, UK, RG7 4RA.
> tel +44 1734 257500, direct +44 1734 257740, fax +44 1734 257553
> gedwards++at++reading.sgi.com, US vmail 59130, UK vmail 7740#, mailstop IUK-311
>-- End of excerpt from Greg Edwards, SGI UK.
Hope this helps,
Guy
--
Guy Russell
Member of the Technical Staff Silicon Graphics Inc.
Email:guyr++at++engr.sgi.com 2011 N. Shoreline Blvd. M/S 2U-923
Phone:(415)933-6113 Mountain View CA 94043
---End of forwarded mail from <guyr> ("Guy Russell")
--
Guy Russell
Member of the Technical Staff Silicon Graphics Inc.
Email:guyr++at++engr.sgi.com 2011 N. Shoreline Blvd. M/S 2U-923
Phone:(415)933-6113 Mountain View CA 94043
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