Re: Screen size vs app,draw process times

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Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Fri, 27 Sep 1996 07:20:34 +0100

Resolution does affect draw times.
The geometry engines often block waiting for pixels to be drawn (not so
much on iR because of the BEF) and the draw won't complete until all
pixels have been written, then it has to wait on the next vertical retrace
before the framebuffer can be swapped. You can see most of this in the stats.

Resolution may also affect cull times marginally because LOD ranging
will vary with resolution.

Rgds,
Angus.

On Sep 26, 6:41pm, Bill Storma wrote:
> Subject: Screen size vs app,draw process times
> Performer users:
>
> I am trying to understand the interaction between the app, cull, draw
> times in a performer scene and how the screen resolution affects the
> performance data. The machine I am using is a 3 pipe RE2, with 2
> RM4's per pipe, running Performer 2.0 and IRIX 5.3. All testing is
> being performed at root level.
>
> As I understand the process from the SGI technical manuals, the cull
> process determines what information is to be drawn into a channel
> (pipe). The draw process then determines which polygons are affected
> and then forwards this list to the graphics pipe. Therefore, if I
> run an application at 1280x1024 vice 1024x768, with the same frustrum
> looking at the same scene, the app and draw times should be the same
> for both programs. The screen resolution should only come into play
> inside the graphics pipe, where the tri's are scanned into pixels.
>
> I have setup this exact scenario, and have noticed that the app and
> draw times are longer for the higher resolution screen. If the
> cull is forwarding the same frustrum data to the draw process and
> the draw is processing the same number of polygons in the scene,
> why are the process times higher with a higher resolution screen ?
> Have I missed something in understanding how the system flows
> information from one process to the next ? Can someone explain
> exactly why the app and draw times are affected by the screen
> resolution ?
>
> Thanks
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Bill Storma Phone: 407-282-1884
> Enzian Technology FAX: 407-282-3013
> Orlando, Fl. 32817 e-mail: bills++at++p3.enzian.com
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>-- End of excerpt from Bill Storma

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