Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Wed, 15 Jan 1997 18:54:35 +0000
Ahh, I assumed the question was iR. RE2 is different.
> The pfEskyMode may be an important factor in this test. If you can
> use PFES_SKY_GND or PFES_SKY instead of PFES_SKY_CLEAR you'll get
> better performance (but I don't know how that translates into Vega).
You won't get better performance on iR, it doesn't support the TAG clear
which RE2 does so by drawing the sky or ground you add graphics load on iR.
> >
> > Question 2: Is there any way to increase the speed of this app to 30Hz?
> >
> > I found that by eliminating multisampling, turning off the Z-buffer
> > altogether, or not clearing the Z-buffer, I can increase the iteration
rate.
> > Unfortunately, I'm not allowed to change those things, since the test
app
> > conditions are supposed to match the simulation conditions.
> > I also find that moving the observer back just a little speeds things
up.
>
> Have you display listed the geometry which you draw?
>
> Seems like that would reduce this usefulness of this test as a
> simulation benchmark.
>
Well I had assumed this was iR so it's was very significant, and it's
realistic for real applications to display list the database for
two reasons 1) on iR you have a huge <16Mb display list on the GE board.
This goes a long way in a vis sim database, it's also good for storing
reusable objects like a vehicle, and rendering something like a vehicle is
probably your worst case graphics host limit in Vis Sim scenario and
potentially where display lists could buy you back some fill.
2) display lists when not on the graphics board are held optimised
on the host and may draw faster. The iR can also DMA the display
list from the host so for reasonably sized lists it's a win,
especially if you have R4400 processors.
In anycase this test is clearly trying to isolate and measure pixel
fill, the way to this is to eliminate other factors.
If you want a simulation benchmark you should run a simulation.
> color and Z buffers if the depth test succeeds. So, you may get a
> measurably better fill rate if you render polygons front to back,
I very much doubt this would be worthwhile on RE2 or iR systems
unless you manage to occlude some transparency, but anything is worth
a try I suppose.
Cheers,
Angus.
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