From:
General Lee D Mented
Subject: Q3A unfair as a benchmark?
I've noticed something rather
disturbing that is probably having a major impact on how most video
cards are scoring in Q3A.
High Quality mode defaults
to having Trilinear Filtering enabled. This feature is available on
pretty much all of the currently selling 3D cards, but only a few of
them actually implement this when Q3A requests it.
Brief background: Trilinear
filtering is done to reduce the appearance of those annoying "bands"
or "zones" you see when you look into the distance in 3D games.
You may have seen this on the floors in Quake2, which used standard
bilinear filtering. To do a trilinear filter, you need to make two bilinear
textures and then average them to create the smoothing effect. The downside
is you have to generate two textures and blend instead of one. This
would be a big performance hit on most 3D cards, so instead they cheat.
Some 3D cards will do trilinear
via mipmap dither (dithering alternate bilinear textures) instead of
doing real trilinear texturing. This costs almost nothing in performance
but gives the image a slightly "grainy" look to it. Cards
that do this include:
TNT
TNT2
Voodoo2
Voodoo3
most current ATI cards I know of
On the other hand, some
cards will actually make two textures and do real trilinear when Q3A
requests it. These cards include:
GeForce
G200 (I think, not positive)
G400 (definately)
most S3 Savage series (they seem to do it free according to postings
by Brian Hook when he was still at iD)
This means that when you
change only the texture setting from bilinear to trilinear, GeForce
and G400 will slow down, but TNT2 and Voodoo3 will not, as they don't
truly implement the feature. This is about as unfair as comparing V3
"22bit" dithered 16bpp versus TNT2 true 32bpp modes, or say
comparing all 3D cards at 1024x768x16, but the Voodoo2 at 800x600 because
it doesn't support 1024.
I would like to request
that sites that have done comparisons of 3D cards note this and possibly
re-score the cards in bilinear mode so we can have a fair comparison
on which to base our decisions of what we buy.