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Comment by CharlesW | Hacker News Reader

I'm a huge fan too, but my understanding is that traditional intra-frame anti-aliasing (SSAA, MSAA, FXAA/SMAA, etc.) does not increase the information capacity of the final image, even though it may appear to do that. For more information per frame, you need one or more of: Higher resolution, higher dynamic range, sampling across time, or multi-sampled shading (i.e. MSAA, but you also run the shader per subsample).

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MSAA does indeed have a higher information capacity, since the MSAA output surface has a 2x, 4x or 8x higher resolution than the rendering resolution, it's not a 'software post-processing filter' like FXAA or SMAA.

The output of a single pixel shader invocation is duplicated 2, 4 or 8 times and written to the MSAA surface through a triangle-edge coverage mask, and once rendering to the MSAA surface has finished, a 'resolve operation' happens which downscale-filters the MSAA surface to the rendering resolution.

SSAA (super-sampling AA) is simply rendering to a higher resolution image which is then downscaled to the display resolution, e.g. MSAA invokes the pixel shader once per 'pixel' (yielding multiple coverage-masked samples) and SSAA once per 'sample'.

I probably only have a basic understanding of MSAA, but isn't its advantage reduced owing to detail levels even in situations where it could be used. There's so many geometry edges in models and environments (before you consider aspects like tessellation) to AA and intricate shading on plane surfaces so to get a good result you're effectively supersampling much of the image.

MSAA actually does, it stores more information per pixel using a special buffer format

What extra information goes in there?

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