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Valve Defuses NVidia Half-Life 2 Issues
suineg writes "Gabe Newell, Valve's main man, has commented on Half-Life 2 and anti-aliasing problems with DX9 cards over at HalfLife2.net: '[The current problems] ...will look like a bright or dark line on the edge of a polygon. This is not a new problem. Artifacts may show up more frequently in Half-Life 2 simply because we've eliminated lots of other artifacts, and because we have a lot of variation in scene lighting due to our art direction.'" As far as solutions go, Newell has some: "ATI has supported... [the centroid work-around] form of anti-aliasing for the 9000 series... [as for] NVIDIA's [hardware], that doesn't support centroid sampling... you trade off some pixel shader bandwidth to clamp the texture coordinates."
How will Half-Life run on cards like the Matrox Parhelia and its 16x anti-aliasing? I believe it is a Direct X 8 card.
Well, I think the idea is that (a) you'd be able to do that on the card, so you wouldn't need to move it to main memory, and (b), you do not need to literally render the whole screen and then shrink it; you can just do 2x2 pixel or 4x4 pixel blocks and then combine those to get each pixel. The intermediate data does not need to stick around.
> What they do is they don't actually sample the entire screen, they basically just run AA on the textures when they are
> rendered, then anti-alias the edges as they are rendered.
How is AA on the textures different from bilinear sampling? Or, how does anti-aliasing the edges cause textures to leak through?