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I just found this interesting example (with Source Code) of a new anti-aliasing technique called “GBAA”, or Geometry Buffer Anti Aliasing. It uses a separate buffer to store geometry information as two-channel edge distance data , then uses a pixel buffer to select which pixel to show at rendertime.
The advantage of GBAA over GPAA is that it gets rid of the second geometry pass. It also does not require any line drawing, something that consumer level GPUs generally suck at. Additionally, having geometry information in a buffer allows us to anti-alias other edges than just geometric ones, most notably alpha-tested edges. The shader just needs to output the distance to the alpha-edge, something that’s easily approximated using gradient instructions. This is also demonstrated in the demo. On the down side it requires additional memory for the geometry buffer, but does not balloon up in the same way as MSAA does.
I’ve got to admit, the results are impressive. You can get the Windows Executable and source code at the site. DirectX10 required (Sorry XP’ers).
via Humus – 3D.
