Half-Life 2 XB360 won't be using tiling to achieve A.A.
- Thread starter Brimstone
- Start date
(newb 
)They didn't clarify why AA as a result of tiling is a bad thing.
It could simply be that it screws compatibility between the cross platform titles they will make for the X360 and PC...or at least complicates things to a degree they wish to avoid.
It does seem to not be using the X360 as intended and maybe even to it's best potential given AA via tiling is supposed to be relatively "free" along side everything else. Another possibility is that we may have just gotten a hint as to that not being the case in practice...or at least for Valve. It's not true for EPIC...but we understand why...wonder what's going on over at Valve if I'm onto something.
It could simply be that it screws compatibility between the cross platform titles they will make for the X360 and PC...or at least complicates things to a degree they wish to avoid.
It does seem to not be using the X360 as intended and maybe even to it's best potential given AA via tiling is supposed to be relatively "free" along side everything else. Another possibility is that we may have just gotten a hint as to that not being the case in practice...or at least for Valve. It's not true for EPIC...but we understand why...wonder what's going on over at Valve if I'm onto something.
scooby_dooby
Legend
How can they 'not' tile?
Seems to be a fundamental problem getting AA w/ EDRAM working on pre-existing game engines.
We need to see game engines designed from the ground up. This reliance on UE is brutal.
Seems to be a fundamental problem getting AA w/ EDRAM working on pre-existing game engines.
We need to see game engines designed from the ground up. This reliance on UE is brutal.
scooby_dooby said:
It sounds like they did, but they didn't like the performance tradeoff that involves. Whether that's a general issue or something that's amplified by their engine's approach, I don't know.
The 'paper' tradeoff is shading, vertex shading. Maybe techniques they're using are heavy on the ol' vertex shading, and they've had too much redundant processing when using tiling. I'm kind of surprised it would be a dealbreaker, though. Maybe there's other issues at hand that we don't have visibility on.
UE3's issue is a general one with regard to MSAA. It's not something specific to Xenos or tiling. They don't tile, because MSAA is very inefficient generally with the techniques they use (and you're really only going to tile if you want to use MSAA).
TheChefO said:From what I understand though, bandwidth on 360 does not allow efficient aa through traditional means.
The eDRAM does use traditional MSAA, so I don't know what Hardnocker is talking about. The only difference is that at 720p resolutions the framebuffer is larger than the eDRAM, so the image must be broken up (tiles) to fit into the eDRAM. They are stitched back together in the system memory. The ROPs write to the eDRAM so they cannot really write to the UMA.
My guess is either they will go with the lower resolution scale up, call DOF and Motion Blurr AA, or go another route and maybe do some sort of edge filtering. Xenos has a lot of extra ALUs not being used much so maybe they are doing anti-aliasing in shaders?
I am more curious if they will use FP10 blending and filtering instead of the shader HDR effect in HL2 Lost Coast.
Similarly: Are we getting soft shadows and self shadowing on all dynamic objects? Looks like it, lets hope it stays! I wonder if they are using dynamic branching for this.
scificube said:
No, Epic's issue is not necessarily tiling, but MSAA. i.e. RSX, 7900GTX, and the X1900XTX have the same problem -- MSAA is a huge penalty using their deferring rendering techniques.
It would be interesting to learn more about why Valve is going this route. VERY astute observation scificube on the cross-platform note. Source's base rendering engine dates to 2001/2002, and even though it seems to have been updated it may have some legacy that does not play nice. e.g. Are they doing an early Z pass? If not tiling wont work anyhow.
