Dreamcast Anti-Aliasing

[Omar]

Hey,

we all know Dreamcast supports Anti-Aliasing in the Form of 2:1 SSAA (1280x480 downsamped to 640x480), which was done in a handful of games (I know of four).

But some sources claim it also supports "Edge Anti Aliasing", and this has always been a mistery for me.
I'd like to know how exactly (and if!) it works.

Does anyone have reliable source material about this on Dreamcast, or 1st hand development experience with it?


To my knowledge, early PC 3d graphic accelerators supported this.
There seem to have been two implementations:
One needs a special game engine designed for this with back-to-front sorting of polygons, tagging the polygon edges to get anti-aliased and then sending it back to the CPU which did the actual anti-aliasing (so it was more of a software thing).
The other method seemed to involve anti-aliasing on polygon edges with semitransparent pixels and had problems with intersecting polygons.

Who knows more, and what is going on on the Dreamcast?

Personally, I have never seen a game with Anti-Aliasing on DC...


(Please do not confuse it with the interlace deflickering filter, which is another story, don't wanna talk about that.)