Dynamix Programmer Dave Moore made a large update to his .plan "intended to be something of an open letter to Tribes players that are asking about the ongoing OpenGL work, and anyone else who might be interested." The extremely lengthy update details some of the difficulties they've had with TRIBES OpenGL support based on the dominance of Quake-engine games that he says influences OpenGL card and driver development away from the type of support required by games like TRIBES. Here's an excerpt to try and capture the flavor of his post:

Now, we come to Tribes. Tribes is, by design, less geometrically complex than Unreal or Quake2, and more complex than Quake. Tribes uses procedural animation for some interior lightmaps, dynamically generates lightmaps for projectiles and explosions, and, what "hurts" most, generates a large number of textures in our terrain engine for detailing purposes. The terrain in Tribes was designed to trade geometric detail for texture detail in order to achieve a good trade off for software rendering and Glide for Voodoo1/2. Every problem we have run into in implementing OpenGL for Tribes has boiled down to: no OpenGL card/driver combo currently available is prepared to handle the amount of dynamic texture shuffling that Tribes requires.

Let me state it baldly. There is no excuse for this that I can see in a current AGP card. Take the Voodoo1 as counterpoint. A card several years old, with a fill rate less than half of a good second generation card like the TNT, the Voodoo1 can download upwards of 300-400 kb of textures per frame, at 30 fps, all the while running an app at 640x480 with a depth complexity of ~3. The cards I have been testing on are sometimes hit with huge frame rate penalties (30-50%) when downloading less than 8 kb of textures (10-30 small lightmaps) per frame with a DC slightly above 2. Swinging your head around on the Tribes terrain can cause pauses of a large fraction of a second. (The "hitches" I've mentioned before.) I'll freely admit I'm not a hardware engineer, but let's look at the math. The Voodoo1 downloads across the PCI bus at 33 or 66 Mhz. AGP 2x has an access rate several times that, and the cards have the capability to leave the textures in system memory, and access them directly as needed. (I should say, theoretically have the capability, it's not utilized in some drivers, notably the TNT Detonator driver set) Why is the AGP card slower?