Preview : Ageia PhysX (page 1: Introduction, physics engines)

10 years after 3dfx, Ageia prepares the release of a new accelerator, the PPU. Also developed for games, this PhysX Processing Unit will, as its name implies, manage physics effects in games or at least some of them.

With time, games have strongly evolved in their graphics and realism. This doesn’t only rely on visual effects, but also on how different elements of a scene interact. Cars no longer move like big blocks without weight and more and more objects are mobile and/or destructible. A good example is Half-Life 2 where the player has to use basic physics laws to progress in the game (for example, he manipulates hollow barrels to build a floating bridge). These aren’t the only type of physics effects and they have to do with everything that is mobile in games.

Physics effects in games concern mechanical aspects; how a body moves and reacts with contact or the way fluids behave. These are the main things controlled by game physics engines. If you hit a crate, it will fall of the shelf where it was stored unless it’s too heavy.

Physics engines

In the video game world, more and more developers use middleware. These are elements developed by third parties such as 3D engines, physics engine, etc. Their existence affects a developer’s load in the way that they can gain time by buying piece of code ready to be used. Another advantage is that the developers of these engines can spend more resources to increase quality. It’s undeniable that physics effects in games have quickly evolved during the past few years thanks to middleware and mainly thanks to Havok, an absolute must in this domain in equipping many games.

Havok isn’t the only one on this market as Ageia released the Novodex engine a little while ago. It has been renamed PhysX, like the name of the PPU. PhysX is a software engine available on computer and video game consoles and which of course is capable of handling the hardware acceleration of PhysX. The two can’t be mixed, however, because a game that uses the PhysX engine doesn’t necessarily support the PhysX card.

Currently, Ageia doesn’t provide hardware acceleration for competing engines and because of this competition between these two physics actors, chances are that they won’t find an agreement on this level. We will probably have to wait for the release of Direct Physics in DirectX for interoperability to happen. Even if Microsoft is working on it, this API is far from being ready and we don’t know if the current PhysX chip will be capable of supporting it. (We have heard rumours that Direct Physics would be 100% CPU).

The development of physics effects in games is still at an early stage and several paths may be taken. The evolution to multicores and in several years their widespread use will seriously increase CPU capacity for physics calculations. GPUs have also become capable of processing some physics calculations, those connected to what we call physics effects. It adds visual realism, but doesn’t affect gameplay. Havok supports this initiative and at the end of the year will release Havok FX, a plug-in for its engine that will use the GPU for these types of effects.

Of course, for Ageia the solution is to use a specifically dedicated processor in order to allow physics to explode in the future. For that to happen, games have to use it. The release of the PPU has been postponed several times as it was announced for the end of 2005, then in February, again at CeBIT and then just after. Today it actually happens. Two games are now available with PhysX support and several new demonstrations will be made in coming weeks at the E3.