The Laws of PhysX

Bouncing off the walls

Regular bit-tech readers may remember that id Software’s John Carmack was in the news recently, saying he wasn’t a believer in dedicated PPUs and that there was no future in them. He pointed to Valve Software’s excellent physics without PhysX. Crytek too have shunned PhysX, building its own physics software for Crysis after examining the potential of both Havoc Physics and the Ageia PPU.

“The guys at Crytek are a great bunch,” Said Dan as we watched Warmonger load, “what I love is that they are actually helping us by showing the world that physics simulation is the future. A lot of people discuss if physics is going to be a big part of games, but I think now we’ve all decided that they are. The second this is that there are only a handful of games developers who have the resources to make their own physics engines. I’d say there are only four companies that could do it and hopefully we can help Crytek in the future to accelerate things. Just because we don’t use the same model doesn’t mean we can’t cooperate with them.”

Dan was on a roll here obviously and quickly carried on to discuss what the alternatives to using a PPU were.

“Crytek is using mainly the CPU but there are supposedly three ways to do it; you can use the graphics board, apparently - and I have a strong graphics background with four years of work in that area, but I know there is nothing happening in the background. It’s hard enough to get SLI/CrossFire working in games (though they have managed to get it working well now) without adding more on top. Every time there is a new effect, like a tree falling, it has to be put back on to the graphics board to render it, so there isn’t a way to substitute it.


“When it comes to the CPU side, dual-core, quad-core, whatever then the main problem is threading. How are you ever going to thread the two things together? It’s all about timing, when the physic effect hits then how is the second core going to time it and cooperate? At the moment, there’s not a single game that supports multi-threading even at a basic level. I reckon we’re years out with that and it’s already been about for two years. The games that are being developed now only use it a bit, for A.I. and so on where they don’t need extreme threading.”

So, unsurprisingly, Dan reckons that the dedicated PPU is the best solution and he was quick to pimp up the PhysX SDK, which can be downloaded for free for bedroom developers and code-monkeys to experiment with.

In direct response to John Carmack's statements yesterday, Michael was quick to step in and said that the original article had been ‘editorialised’.


“Carmack has said this type of thing before though and I challenge you to dig a little and see what Carmack said about 3D graphics when they first came out – he said it wasn’t going to happen...There are guys who are developing games who say they think they can program it themselves and do it without the hardware and we say; ‘Really? Show us.’...When they have to prove it then it’s a different story. When a story like that breaks then it’s great and a lot of people read it, but the reality is that we’re excited because we can come here and show it.

But what about the future of PhysX and physics, the original PPU has been out a while now so can we expect any new developments or designs in the coming months?

“We’re a hardware company at heart, no matter how much software we do. We aren’t stopping with the hardware at all and you will see next generation products from us in the future. When you think about physics as a whole, do you think we’re even close to tapping the potential of where physics can be? Nothing close. Think of movies like The Lord of the Rings with millions of things exploding on screen at once.”