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ATi frame buffer read speeds

Tagrineth

Dragony thingy
The Khan Artist said:
Well, I installed the Cat 3.5 drivers (yes, and Control Panel), and this is what I get with Jabo's 1.5.

Take a good look at the yellow fences in Zelda - see how they don't get antialiased? And yet most other surfaces do. Same with aniso.
Uh... hun, the fences are called 'alpha textures' and those don't get anti-aliased by multi-sampling, ever. Period. Ever played Counter-Strike with AA and looked at the fences?
 

radTube

lazy bastard
This thread reminds me of the times when I bought my r8500... except that back then the drivers actually deserved the negative attention. Oh well. I'm glad nVidia at least keeps releasing those bugless drivers of theirs.
 

Tagrineth

Dragony thingy
radTube said:
This thread reminds me of the times when I bought my r8500... except that back then the drivers actually deserved the negative attention. Oh well. I'm glad nVidia at least keeps releasing those bugless drivers of theirs.
Um. Dude. That statement deserves a beautiful bitch-slapping. "Bugless nVidia drivers"? Not by a very, very long shot.

Even while Carmack was trumpeting the nVidia "Golden Standard" drivers, people had lists of which Detonator versions were most compatible with which games.

And Carmack's latest statement was that nVidia's drivers were "A LITTLE BIT" better than ATi's.

Hell, I think even nVidia knows how "bugless" their drivers are, considering a new Detonator set gets released/leaked every other week... if they're so 'bugless' why so many revisions?


@Khan Artist: I can tell you exactly what's wrong with Alpha Textures. Multi-sampled AA is designed to look for polygon edges. There are rarely polygon edges in alpha textures (the whole point is they alleviate the need for mass polys). Ergo multi-sampling can't detect the aliased edges, and doesn't anti-alias them. Super-sampling (ATi R2x0, nVidia NV1x, 3dfx VSA-100, SiS 315 and lower, PowerVR series 2 and 3) over-samples the entire scene (3dfx could do 'targeted' AA but it required some extra code) and thus does catch the textures.
 
OP
The Khan Artist

The Khan Artist

Warrior for God
Tagrineth said:
Um. Dude. That statement deserves a beautiful bitch-slapping. "Bugless nVidia drivers"? Not by a very, very long shot.

I think he was being sarcastic.

@Khan Artist: I can tell you exactly what's wrong with Alpha Textures. Multi-sampled AA is designed to look for polygon edges. There are rarely polygon edges in alpha textures (the whole point is they alleviate the need for mass polys). Ergo multi-sampling can't detect the aliased edges, and doesn't anti-alias them. Super-sampling (ATi R2x0, nVidia NV1x, 3dfx VSA-100, SiS 315 and lower, PowerVR series 2 and 3) over-samples the entire scene (3dfx could do 'targeted' AA but it required some extra code) and thus does catch the textures.

OK, that makes perfect sense. Thanks.

Wouldn't it be possible to, say, perform edge detection on the texture, then clip and tesselate? This would be a lot of work on the software side, but modern video cards could more than handle it.
 

Remote

Active member
Moderator
Indeed, it's all about reputation. In the common eye, when ATI releases new drivers it's to fix what's broken and when nVidia does the same thing it's because they found a way to squeese out a little bit more performance...
 

Tagrineth

Dragony thingy
Wouldn't it be possible to, say, perform edge detection on the texture, then clip and tesselate? This would be a lot of work on the software side, but modern video cards could more than handle it.

Video cards, yes. Processors (which would need to do that texture edge-check), no.
 

ector

Emulator Developer
khan, of course that would be possible, but it would take a tremendous amount of work to do, and I doubt the gfx plugin authors care so much about a few fences =)
 

Tagrineth

Dragony thingy
The Khan Artist said:
Yeah, I guess it would be rather CPU-intensive... but the results could be cached.
You can't cache it. The moment you move it'd have to be dumped and re-tested... because what if the texture animates? Or shifts in any way whatsoever?
 

nephalim

Psychic Vampire
It would be a ridiculous performance trade-off for a few fences...it'll be incorporated into the GPU's of new cards soon...or not...
 

radTube

lazy bastard
The Khan Artist said:
I think he was being sarcastic.

I was being sarcastic... gotta remember those smilies next time :rolleyes:.

nVidia is like the micro$oft of the video card industry. They couldn't care less about their customers. They actually seem to treat their customers as just another necessary evil. Driver-guru Omegadrive's take on the subject: http://www.omegacorner.com/

Sorry about going OT once again...
 

ector

Emulator Developer
Oh yes you could with some tricks.. for example, render at 4x resolution to a texture, and use blending or a pixel shader to downsample.. Or render four times with slight offsets and use a pixel shader to average them.
 

Tagrineth

Dragony thingy
ector, you do realise that looks like absolute crap compared to real AA? Hell, it looks like absolute crap period...

Not to mention it'd MURDER performance, even more so than native 4x supersampling would.

Edit: Easier way to do "4x Supersampling", create four render targets each at a slight offset and blend them with a pixel shader... but again, it'd either look really bad and/or be really impressively slow.
 

ector

Emulator Developer
Edit: Easier way to do "4x Supersampling", create four render targets each at a slight offset and blend them with a pixel shader... but again, it'd either look really bad and/or be really impressively slow.

Well that's what I mean you would do.. It would produce the same results as 4x supersampling which at leasts smoothes stuff out a little, and the new radeons are ridiculously fast so speed wouldn't be much of a problem since what we're talking about is emulating the N64 =)
 

Tagrineth

Dragony thingy
ector, the new Radeons are ridiculously fast, yes, but you're talking about 4X or more frame buffer size and 4X the fill rate requirement, plus a surely somewhat complicated weighted pixel shader to merge them, and 4X the bandwidth requirement. The FPS would be divided by slightly more than 4. Even on the latest Radeons, that's kinda slow. It just isn't worth it.

Instead we could go faster and let the graphics plugin sort the polys the same way the N64 does and then use Line AA, same as N64. It'd have a better result and it'd be faster. The latest Radeons support line AA (though it needs to be enabled in a tweaker).
 

ector

Emulator Developer
Sure, but that still wouldn't solve the alphatest-textured fences, which was the whole point of the entire discussion =)
 

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