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I know the principles behind how QCSAA is supposed to work (as opposed to how, say, regular CSAA works) and subjectively after some testing I like the style it lends to the image enough that I'm considering turning it on by default in certain situations. The question is - I've read that in practice it doesn't work quite as described. Theoretically, it should only be considering coverage samples from the the nearest edges of neighboring pixels along with the local pixel's samples in its calculation, which makes sense. But I've seen it claimed that it's actually just a blur filter over an antialiased image - that is, a 8xQCSAA frame is just rendered using 8xCSAA and then slightly blurred, using the finished pixels as samples.

This is obviously not the same thing. Does anyone know how it works for sure?

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closed as off-topic by Josh Petrie Dec 2 '13 at 17:49

This question appears to be off-topic. The users who voted to close gave this specific reason:

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Depressingly, these implementations have changed multiple times, through the years (even multiple times a year, at some points). There has never been a guarantee that the algorithms for any AA style (much like non-standard texture compression, etc) would remain static, and these algorithms were very, very frequently changed in the early days, in order to improve performance, while fudging image-quality/precision, in competition with ATi. These days, that's mattered much less. That said, the current state of the algorithm is wholly unknown to me. – Norguard Feb 20 '13 at 19:03
Yes. – Trevor Powell Feb 21 '13 at 8:23