A recent post in the Half-Life 2 forums questioning the possibility of full screen anti aliasing with Half-Life 2, especially on Nvidia GeForce FX graphics cards, has caused many gamer"s a headache. Gabe Newell, Valve Software"s managing director, now posted more details on the matter:
Since people seem to be hyperventilating over the anti-aliasing issue, I thought I"d update everyone.
1) How bad is the problem?
With current multi-sample implementations of anti-aliasing, you may sample texels outside of the polygon boundary, which may result in sampling light maps from other polygons. This has always been a problem. This is a problem with Quake 1, Quake 2, Quake 3, Daikatana, Sin, Elite Force, Half-Life, Counter-Strike on the X-Box, or any game that uses packed lightmaps with multi-sample anti-aliasing.
You would see these artifacts on polygon boundaries where the wrong lightmap is being sampled. It will look like a bright or dark line on the edge of a polygon. Gary McTaggart brought this up in an email because he is being pretty hardcore about graphics quality right now. This is not a new problem. If you"ve run a game that uses lightmaps with anti-aliasing turned on, then you"ve been seeing these artifacts the whole time. 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. To put this in perspective, not doing tri-linear filtering on mipmaps is a lot worse.