Impact Retention and Self-Collision Prevention

This one is actually something I have been wanting for a long time. Have you ever played an MMORPG, FPS, or even an RPG game where the clothes on your characters, or even the cloth in the environment is very realistic, but as it waves or moves it clips into other objects. The best example I can think of are the capes in Guild Wars. These capes signify your guild and as they hang on your back, the can clip into your legs or your armor while running or standing still. For those of you who may not understand what I mean by clipping, it's when one object and another object exist at the same point in the engine. Since the engine doesn't know what to do, it renders both, which usually results in things like being able to see a gun sticking out of a closed door when a player is up against it, or armor being rendered partially through the wearer's cape. This kind of thing occurs all the time and we have become very used to it. With this new feature in the PhysX engine, only one object can occupy the same location at a given time. This means that if the cape is in one spot, the armor cannot move through the cape, and if it tries to, the cape will be ruffled accordingly.

Physics Power Struggle
These new features are all very much revolutionary and will, beyond a shadow of a doubt, be implemented in future engines and games, but what is there to play it on? Well, the two big names in the gaming physics area are AGEIA and Havok, and they are both trying to get you to use their product.

One of the most common misconceptions is that AGEIA and Havok are competitors. This is not the case at all. You see, AGEIA makes their money from selling the PhysX hardware. Their PhysX API, the software side of the physics performance, is licensed to game developers for free. Yes that’s right, free. Now let’s look at Havok. Havok makes their money by licensing their API out to game developers. That means that they are not really competitors because each is profiting from a different means. However, the fact that they are both in the physics market and that they both offer their own physics engines does lead to some growing pains for the technology.

You see, in order to work most effectively, the PhysX hardware needs to be run on a game that has the PhysX API implemented from the ground up. Currently, the only game that really has this is CellFactor: Combat Training. The performance increase offered by the PhysX hardware in this game is truly amazing, as relayed in our review of the ASUS PhysX P1. However, in other games, such as Tom Clancy’s Ghost Recon: Advanced Warfighter (GRAW), the performance increase from the PhysX hardware is negated by the performance decrease sustained by the video card as a result of having to render the extra detail. Unfortunately the PhysX hardware does not work to its potential on all games that have physics, and doesn’t work at all on games that do not support it; using the PhysX hardware on Counter-Strike: Source will not give you a performance increase. This is due to the fact that the PhysX API is not the same as the Havok 2 engine or any other variation of a physics engine that is out there. The PhysX API takes advantage of various features of the PhysX hardware that other physics engines do not.

So although Havok and AGEIA are not technically competitors, the competition between their two APIs is causing some problems for the growth of gaming physics. Each company has quite a few game developers working with their physics engine on games slated for release in the near future. However, the benefits of the PhysX hardware, or any other physics hardware for that matter (the G80’s Quantum Physics Engine capabilities not withstanding), are diminished when the game being played does not utilize the physics engine designed for that hardware. For instance, without the PhysX API implemented in a game, the PhysX hardware has to emulate into the given physics engine, which limits performance of the hardware and does not utilize the majority of its features.