Questions about Unreal Engine 3 and AA implementations

[Kaotik]

Having a bit of argument on another forum, as one member can't accept the fact that DX9 deffered renderer (with multiple render targets) can't support MSAA, excluding driver forced solutions/hacks.

But then, there's some Unreal Engine 3 games, like the infamous Batman: AA which support even in-game AA, and uses DX9 renderer - so what's the deal, how does Batman do it and why doesn't every UE3 game do it the same way?

(And I am right on the dx9 deferred + MSAA case, right?)

 

[Arnold Beckenbauer]

UE3 is not a deferred renderer. Some smart people say, that UE3 uses some funky render targets, that make MSAA under DX9 impossible.

But yes: DX9 doesn't allow to use MSAA on MRTs.

 

[jlippo]

UE3 is not a deferred renderer. Some smart people say, that UE3 uses some funky render targets, that make MSAA under DX9 impossible.

But yes: DX9 doesn't allow to use MSAA on MRTs.

From what I remember it does have deferred shadows and atmospherics, but it is a forward renderer.
This is similar to how Crysis did many of the effects.

Many UE3 games have 2xAA on X360, but when those deferred FX are composited to the image it basically erases the AA.

 

[brain_stew]

The AA in Batman was coded by Nvidia.

 

[Kaotik]

The AA in Batman was coded by Nvidia.

And according to AMD was nothing but standard DX9 AA method with vendor-id check

 

[Graham]

From what I remember it does have deferred shadows and atmospherics, but it is a forward renderer.
This is similar to how Crysis did many of the effects.

Many UE3 games have 2xAA on X360, but when those deferred FX are composited to the image it basically erases the AA.

To the best of my understanding, this is correct.

Roughly, UE3 does a base pass for static lighting, and then an extra pass per light on affected geometry (same with decals). The one exception is it'll do a full screen dynamic sunlight in the base pass on the consoles.

I'm not entirely sure how the shadows are composited, but I believe they are written into alpha for each light pass as a deferred screenspace pass. This is why modulated shadows are so popular in UE3 games, because they don't require this extra pass.

So if you are willing to take the hit, there isn't any real reason why you can't use AA, you just won't get them on high quality shadows in some situations.

 

[Blazkowicz]

UE3 is not a deferred renderer. Some smart people say, that UE3 uses some funky render targets, that make MSAA under DX9 impossible.

But yes: DX9 doesn't allow to use MSAA on MRTs.

don't radeon X1800 and newer allow this?