Having made such a splash at last year's Game Developers Conference with its announcement of the world's first dedicated physics processing unit (PPU), Ageia, the small Silicon Valley startup with giant ambitions has followed through with its vision of hardware physics acceleration. Previously available only with custom systems assembled by enthusiast-oriented firms like Alienware and Northwest Falcon, the first PhysX cards are now widely available from the usual retail channels, offered by Ageia's board partners, ASUS and BFG.
Game physics have taken a more prominent role in modern games as developers strive for greater realism to create more immersive environments. Features like rag doll physics and deformable terrain have gradually become part and parcel of game development now and they all require physics in some form or another. Usually, the CPU has done most of this work. However, the general-purpose nature of the CPU means that it is not the best candidate for a specialized task like physics calculations, which requires extensive floating-point capabilities and memory bandwidth. Simulating collision detection for potentially tens of thousands of particles and objects does not come natively to the CPU.
Another competing approach taken by physics middleware developer, Havok, in collaboration with NVIDIA, has been to utilize modern graphics cards (Shader Model 3.0 capable) to simulate these physics effects, especially in a dual GPU configuration. ATI too has hinted at a similar implementation but there are only scant details currently. Again, this may be trying to fit a square peg into a round hole. Instead of using existing hardware like what the competitors are offering, Ageia goes for the logical but bold move of having a separate processor optimized for physics.
A gaming trinity of CPU, GPU and PPU working together to generate the kind of immersive environments demanded by gamers today. That is what Ageia envisions as the future of games. According to Ageia, its PhysX processor will allow for features like universal collision detection, rigid body dynamics, simulation of joints and springs, fluid dynamics, smart particle interaction and realistic simulation of clothing. These effects not only increase the eye candy quotient for games but also potentially expand game play possibilities by enabling users to modify and interact with the game environment. Getting one's head sliced off by flying shrapnel from an explosion in a game may not be to everyone's liking but it definitely raises the bar on realism. Such an effect should be relatively simple once physics enters the equation.
So what exactly is the PhysX PPU and how does it work? To answer these questions, we have a retail version of the ASUS PhysX P1 in our labs today. Bundled with the first of many (we hope) promising games to support PhysX - Tom Clancy's Ghost Recon Advanced Warfighter, here's our impressions of the first physics acceleration hardware: