T-buffer Technology

What's the deal with T-buffer?

One issue that has caused a lot of debate online recently are the new T-buffer effects present in the Voodoo5 cards. In particular, the issues range from whether or not gamers will use this feature to if it's more important than hardware T&L available on the GeForce 256.

If you're not familiar with T-buffer, we took an in-depth look at this technology back when it was announced last July. Essentially with T-buffer technology, 3dfx wants to bring Hollywood-quality effects to the PC. T-buffer technology will bring three main new visual quality features to the Voodoo5 series: motion blur, depth of field, and full-scene anti-aliasing.

The first two features, motion blur and depth of field, have spawned some controversy. With motion blur, objects in motion are sampled multiple times as they move across the screen. This gives the object a ghosting effect similar to one seen in a camera. The argument is that with motion blur, gamers playing first-person shooters such Quake3 and Unreal Tournament with motion blur enabled may have a difficult time aiming at their competitors.

Motion blur in Quake3

More motion blur, note how difficult it is to aim at your opponent

Continuing with the "Hollywood on the PC" theme is depth of field. Specifically, with depth of field, objects at various distances are seen as in our out of focus, similar to the effect from a camera lens. The argument here is similar to the one for motion blur, will gamers really want to use this feature?

Objects near the camera are seen out of focus on right side image

Personally, we see more use for depth of field, as it could be used to enhance racing games and to a similar degree flight sims. Not to mention the cool special effects game developers could create for other genres - for instance realistic concussion grenades that actually leave you disoriented for a few moments.

The final feature and the one most accepted by the gaming community is full-scene anti-aliasing. If you've played any football game recently you've probably noticed the jagged edges on yard lines and sidelines. Running up stairs is another good example of these jagged edges. With full-scene anti-aliasing, these edges are smoothed out, making them look straight. For the past few months, Dreamcast gamers have enjoyed playing NFL2K in all its full-scene anti-aliasing glory.

Anti-Aliasing on right

Besides motion blur, depth of field, and full-scene anti-aliasing, T-buffer technology also adds soft shadows (designed to give the edges of shadows a softer appearance) and soft reflections. (gives the reflection a more realistic appearance - based on the texture and distance from the reflected surface)

Soft reflections in action

The cost of T-buffer

All these effects come at a performance cost. 3dfx hopes to minimize the number of extra passes to 4-8, but at this point the actual number is still unknown. Since the Voodoo4 doesn't offer the fill-rate of the Voodoo5 products, T-buffer effects won't be used on this model. 3dfx wants to keep the framerate at 60 fps and feels a fill-rate of at least 667Mpixels/second is necessary to meet this goal with T-buffer effects enabled.

What 3dfx isn't stating is exact numbers on the performance hit T-buffer effects will bring. Since they haven't received sample units yet, the final answer remains unclear. Hopefully we'll all know in the coming months, so the T-buffer debate can finally be put to the test.