Anti-Aliasing is where the 3D card blurs pixels so that you don’t get jagged edges on polygons.
There are two ways for a 3D card to generate anti-aliased images. One approach is at the individual polygon level, requiring you to render polygons in back to front of the view, so each polygon can blend appropriately with what is behind it. If you render out of order, you can end up with all sorts of strange effects.
In the second approach, you render the whole frame at a much larger resolution than you intend to display it, and then when you scale the image down your sharp jagged edges tend to be blended away in the scaling. This second approach gives nice results, but requires a large memory footprint and a lot of memory bandwidth, as the card needs to render more pixels than are actually in the resulting frame. Most new cards handle this fairly well, but still have multiple antialiasing modes you can choose, so you can trade off performance vs. quality.
Filed under: Games engines, Games research
