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."

Comments

Trade-offs

[JonoPlop]

Artifacts may show up more frequently in Half-Life 2 simply because we've eliminated lots of other artifacts

What? Apart from not making much sense, is this implying that new artifacts are being traded for a lot of older ones? (i.e. get rid of lots of old ones, but by doing that, introduced some more in the process)

Re:Trade-offs

[samael]

Nope, it means that things that previously would have faded into the general 'unrealism' that pervades computer games stand out more and more when the other problems aren't there along with them.

Look at (for instance) Quake3. Point out a couple of problems with the graphics. Now look at Quake. The problems that FF has are almost certainly there too, but you won't notice them because other problems are far more glaring.

Centroid workaround

[Sesse]

Now, would somebody please explain what this "centroid" workaround is all about? Ie. technically, what does it do? :-)

/* Steinar */

How does this happen?

[Tom7]

Based on my understanding of 3D rendering, I don't see how this can happen.

I thought that FSAA worked by one of two methods:

- Render the entire screen at a higher resolution (double width and height, for instance), and then downsample it to the screen resolution

- Render the same scene at screen resolution several times from slightly (sub-pixel) different locations, then mix the images together

Either way, I don't see how texture coordinates would be disturbed such that parts of other textures show through at boundaries. Can someone with an understanding of modern graphics hardware clue me in?

Re:Selective antialiasing?

[Merlin42]

Uhh ?!?!?! Who said anything about tranlucency?

This has to do with the interaction b/w the programmer doing things 'behind the back' of the driver (ie packing multiple logical textures into one texture as far as the driver/card is concerned) and the driver/card doing things 'behind the back' of the programmer (ie multisample antialiassing in such a way that texture cooordinates may fall slightly outside the range the programmer specified).