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.