Final thoughts

First off, we’d like to thank ATI’s Will Willis for answering our questions while he’s on the road at GDC. We’ve provided a few choice slides from ATI’s GDC physics presentation in this article.

As it stands now, the idea of GPU-based physics is an interesting one. It has the inherent advantage of not requiring any additional hardware to buy: that Shader Model 3.0 GPU in your PC now is all you need to get up and running. With millions of Shader Model 3.0 cards already out on the market, Havok FX has a huge installed base of potential users that any game developer would be foolish to ignore. At the same time though, the million dollar question that everyone wants to know is what kind of performance impact will GPU-based physics acceleration have on your game performance?

According to NVIDIA, in order to realize the best performance, you’ll want to have a GeForce 7600 GT at a minimum, with GeForce 7900 GT/GTX delivering even better performance, and the most optimal solution being two GeForce 7900 GTX cards running in SLI. If this is indeed the case, you’re going from an audience of potentially millions of users, down to just tens of thousands. This is where ATI’s solution could be interesting, as they’re proposing that instead of running, say two Radeon X1900 XTXs in CrossFire mode to juggle the graphics rendering/physics load, you can instead combine a $500 Radeon X1900 XT for handling graphics, with say a $150 Radeon X1600 XT card for handling physics.

On top of all this, enter AGEIA’s PhysX PPU. Will argues that while on paper AGEIA may look better, in actuality they aren’t doing anything that can’t be handled on the GPU today, simply because there are no games on the market that are truly taking advantage of all of the PhysX PPU’s capabilities outside of AGEIA’s Cell Factor game demo.

I agree that if true, this is a pretty compelling argument in favor of GPU-based physics, but the truth is that we won’t know the answer to this until later this year once more physics-accelerated titles ship. As we all know, the benchmark is going to be Epic’s Unreal Tournament 2007. If AGEIA’s PhysX card can deliver better performance than GPU-based physics, AGEIA would have a pretty compelling argument in their favor. No one knows what kind of a performance hit accelerating physics effects is going to have on the GPU’s performance at 3D rendering; the hardcore crowd isn’t going to want their GPU handling anything other than 3D, and will want a dedicated processor for physics, while more casual gamers probably wouldn’t mind the performance hit if it isn’t too significant. I also wouldn’t be surprised if Epic were to provide a custom gameplay experience for AGEIA users.

The bottom line is that it’s too soon to come to any definitive conclusions on either technology. There’s no denying the potential cost advantage of the GPU-based approach if the performance impact isn’t too significant. In this regard I really do think that AGEIA may be out of touch with the market. From the outside looking in, it really does seem to me that AGEIA’s based their entire approach around 3dfx’s original Voodoo Graphics accelerator. There’s nothing wrong with that, as the Voodoo Graphics was the pioneer of an entirely new industry. And while it’s true that Voodoo Graphics initially launched at $300, it was a niche product at that price point. Personally, I gladly paid $300 for my Diamond Monster 3D when it first came out, but Voodoo Graphics didn’t really take off until:

1. Memory prices came down. Remember that the original Voodoo Graphics required 4MB of memory
   
2. Additional board partners came onboard. 3dfx initially launched with only two board partners, Orchid and Diamond Multimedia
   
3. GL Quake. Before GL Quake debuted, there were only a handful of titles with 3dfx support. Most notable of them was Tomb Raider. Once id finally released GL Quake, 3dfx finally had a killer app that was relevant among the hardcore crowd: I was the buzz of my college dorm once I booted up GL Quake for the first time. Everyone who was into PC gaming dropped by for at least one demonstration. GL Quake looked better than VQuake too, and thus 3dfx’s Voodoo 1 was a more justifiable purchase (remember that 3dfx’s card sold for considerably more than Rendition’s).
   

In my opinion, AGEIA needs all of this to happen for them in order for PhysX to really take off. They need more board partners so that prices can come down, and just as importantly, they need a killer app that will drive hardware sales. This killer app not only needs to deliver better performance, but more immersive gameplay as well. 3dfx managed to pull all this off with Voodoo Graphics, AGEIA will needs to pull it off also in order to be successful, especially now that larger players like ATI and NVIDIA are now essentially getting into the physics business. And with ATI and NVIDIA constantly delivering new GPUs, AGEIA’s going to have to remain on their toes for the foreseeable future.

3dfx didn’t run into this problem until much later down the road, and we all saw what ultimately happened to them once they faced it.