| MikeB said: @ Kynes You said that Cell is great doing AA Compared to what? - I said it can do AA and flexibility is a benefit. - I said the 360 does not have a real technical advantage regarding anti-aliasing. I didn't say anything with regard to performance vs the RSX, however I can imagine this flexibility to provide for potentially big benefits and this approach to be used efficiently together with other deferred rendering techniques. |
Any programable processor is more flexible than fixed function, but it doesn't means that is practical (ATI R520 is an example of a debacle due to not using fixed function to do AA resolve)
Regarding to 360-PS3 AA: http://forum.beyond3d.com/showthread.php?t=46241
RSX - The relation to the G7x series would mean that the ROPs are capable of handling 2 multisamples per pixel per cycle. Basically, in a bandwidth unlimited scenario, 2xMSAA or Quincunx is free. But do note that the double pumped Z-only fill rate is only effective without MSAA and that this can be important for certain effects such as rendering shadows; with 2xMSAA the z-only fill rate falls in line with the colour fill rate.
However, with the use of multiple render targets or higher resolutions, the 22GB/s is very much a concern for framebuffer bandwidth. 4xMSAA would be very costly to fillrates, halving the rates compared to 2xMSAA and also doubling memory bandwidth consumption since the framebuffers scale linearly.
Xenos - As noted in the B3D article, the ROPs are designed to handle 4 multisamples per pixel per cycle. All fill rates are full speed, and the Z-only fill rate is also double pumped.
RSX is a fillrate/bandwidth starved chip. That's the reason why in some cases PS3 games have a blur filter instead of AA, because a blur filter is more compute intensive than bandwidth intensive. You can't help it's bandwidth problems doing AA resolve on a SPU.
