Originally Posted by sebbbi :
We have a fully deferred renderer, so 2xMSAA would cost a lot. Naive implementation would double the lighting cost (currently our lighting is around 25% of our frame time). There are some clever tiled deferred renderers (for example in Black Rock's Split Second) that do sample frequency lighting only to tiles that have MSAA edges, but even with really small 4x4 tiles huge amount of pixels require double lighting (one edge pixel in tile requires the whole tile to be lighted by sample precision). With DX11 (compute shaders) you can do even more fine grained lighting, but that's quite hard to do for consoles. And in addition to the double lighting cost, you need memory space (and bandwidth) to resolve the 2xMSAA deferred buffers, and naturally (on Xbox) you need to multipass some geometry, as 2xMSAA deferred buffers take a lot of EDRAM space. Post process antialiasing doesn't require any additional memory, as you already have your g-buffers in memory, and you can reuse those memory locations after lighting is complete.
So, basically 60 fps deferred renderer with 2xMSAA is pretty much impossible to do on current consoles. Post process AA is pretty much the only choice. Fortunately FXAA2 looks better than 4xMSAA on average case, and it doesn't blur the image as much as other techniques such as DLAA do, and still does very good job in removing all the jaggies. And unlike MSAA, it also antialiases all transparencies and can be easily done after tone mapping (antialiasing before tone mapping is just wrong). Surprisingly it looks pretty good even on one pixel wide geometry (such as power lines and fences), but doesn't help with subpixel geometry (like other post antialias ******s such as MLAA).
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