AFR > Split, Checkboard

Pelu

Golden Member
Mar 3, 2008
1,208
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poll, pool,, or pooool dunno how that is written lol...

which one you like more...

AFR
Split
Checkboard...

and i mean the multi gpu styles to throw to you the frame...
 

FalseChristian

Diamond Member
Jan 7, 2002
3,322
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I have found with OpenGL games Split-frame rendering is the way to go and for DirectX games AFR1 and AFR2 are close enough so you can try both.

Checkerboard is called Tile-based rendering which is found only on ATI cards. It's slow so don't go that route.:)
 

Pelu

Golden Member
Mar 3, 2008
1,208
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AFR1 and AFR2????

I dont get it... there is more than one AFR???
 

BFG10K

Lifer
Aug 14, 2000
22,065
1,237
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First and foremost multi-GPU solutions should be focusing more on smarter multi-GPU AA modes. Two cards running 2xAA should be able to deliver 4xSGMS and 2xRGSS at the same performance hit as a single card running 2xAA.

Failing that, bring back super-tiling.
 

ViRGE

Elite Member, Moderator Emeritus
Oct 9, 1999
31,516
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Wouldn't that be a tremendous waste of resources though? 2x->4x MSAA is not even close to halving the performance of a card in most situations.
 

BFG10K

Lifer
Aug 14, 2000
22,065
1,237
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Originally posted by: ViRGE

Wouldn't that be a tremendous waste of resources though?
No, quite the opposite actually. Instead of relying on application specific optimizations to attain scaling, every board would be working at 100% efficiency at all times regardless of the application, assuming CPU limitations are not present.

Any 3D game that allows AA (probably 99% of such titles) would automatically scale and provide a benefit over a single card without the need for profiles. And best of all, compatibility would be 100% transparent to the application because scaling would be done at the hardware level.

2x->4x MSAA is not even close to halving the performance of a card in most situations.
That was just one example. You could have two boards @ 4xAA giving 8xAA for the same performance hit as one board @ 4xAA.

Or you could have four boards doing 2xAA and providing 8xAA at the same performance hit as one board doing 2xAA.

Or four boards @ 4xAA could provide 16xAA at the performance level as one board doing 4xAA.

The possibilities are endless.

Better still, super-sampling would become free as every board has to capture one shader/texture sample anyway. Super-sampling has a high cost on single cards so this would be a major bonus.

Four boards could provide 4xSGSS for free as it would cost exactly the same as one board not doing any AA at all. This would provide amazing image quality, especially in modern games that suffer from shader aliasing.
 

ViRGE

Elite Member, Moderator Emeritus
Oct 9, 1999
31,516
166
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Sure, it would be for "free" but you're adding an additional card to do something that would normally reduce performance by what, 20%? So instead of a proper profile that gives you a 50% boost across the board, you get an IQ that would normally cost you 20%. That seems like a waste of resources to me. It's a great option for games that haven't been profiled, but it's under performing compared to a properly profiled game.
 

BFG10K

Lifer
Aug 14, 2000
22,065
1,237
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Originally posted by: ViRGE

Sure, it would be for "free" but you're adding an additional card to do something that would normally reduce performance by what, 20%?
For multi-sampling yes, but not for super-sampling; 2x super-sampling cuts the performance in half on a single card while 4x super-sampling reduces it to one quarter. Super-sampling is highly desirable to combat shader aliasing in modern games but is prohibitively expensive.

Also I was thinking about this more and I realized my suggestion is even better than I originally conceived. I originally proposed using four boards to get 4xAA at the same hit as one board with no AA but in actual fact if you're clever with your sample positions you only need two boards to do it.
 

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