One question for Joker454:
With the advantage of high bandwidth, why is Forza 3 limited with transparencies (cannot see through car glass window) whereas GT5P has abundance of transparencies and sports a 4xMSAA?
I think we cannot point our finger at one single factor and declare the winner. There are many ways to work around the problem.
GT5p does not have an abundance of transparencies, it has very few actually, totally typical of a PS3 game. See through rear windows are very little transparency, and their dust particles are the typical no detail low res stuff all PS3 games do (see the new Ratchet demo of R&C for another example of obvious low res transparency buffers). The rest of the game is all very overdraw predictable.
The cost of msaa is on a per primitive basis, and GT5p has the typical stripped down 60fps console environment that would make 4xmsaa doable. The cars in GT5p look great, but everything else just screams 60fps compromise.
I doubt Forza3 tinted the rear glass because of transparency limitations, they must be hitting some other limitation. Same with a2c, hard to know why they went with that, maybe they are using the alpha channel for something other than alpha. I don't have the game yet so I don't really know.
In the end there might be a more obvious answer to all of this. PD has been making car games forever, they might just be better at it. For example I'd wager that PD's vehicle shaders are smarter (ie, less cycles) than Turn 10's. In the end though you can't get blood from a stone. Msaa and transparencies are two weak points on PS3 hardware that have to be designed around, and PD did just that.
Nebula said:
But didn't EDRAM and higher AA increase polygoncount as in multipass? Do I remember it right with 2xAA -> 15% polygon redraw and 4xAA 30%?
I think it was 1.4x poly hit for 2xmsaa, and 1.6x for 4xmsaa. Both approximations of course. With 60fps racing games though they tend to skimp on environments and blow the poly budget on the cars. Given that many cars can clump together, you can easily get much worse than a 1.4x tiling hit from even just 2xmsaa. It's even worse with vehicles compared to humanoid type meshes, because the vehicles are horizontal in design and hence more likely to straddle tile boundaries even if broken up into many individual meshes. Humanoid meshes are more vertical in design, so they are less likely to straddle tile boundaries after having been broken up into parts.
