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Ageia PhysX vs. Nvidia SLI Physics

Can Ageia's PhysX Card Bring Real-World Physics to Games?
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Recently, the concept of physics engines and their recent commercialization for graphics applications have been a source of controversy on numerous Web forums. Among three variations available, the Ageia's PhysX card represents a dedicated hardware solution. Other options involve the use of physics calculations through Nvidia SLI graphics cards or splitting the calculations into another thread that gets offloaded onto an available CPU core.

At $299, Ageia's card is expensive. Admittedly, enthusiasts are used to paying a lot for their cutting-edge gear, while in this case the actual value that the card offers games has yet to be seen. Graphics cards sold today support HDR rendering and pixel-shader effects, the benefits of which are easy to see in countless screen shots published everywhere on the Internet. However, most people do not know what the advantages of Ageia's physics card are.

There just aren't enough real-world applications and demos out there to serve as proof of what Ageia's physics cards offer. Screenshots and videos on the company's Website will hardly convince the skeptics. However, Ghost Recon Advanced War Fighter, the first game available in the market with PhysX support, is a start. But until a critical mass of games with PhysX support is released, the card's price will likely turn many potentials buyers off. "Rise of Nations : Rise of Legends" is out now, but this review was finished weeks before.

To make things even more difficult for Ageia, Nvidia has announced that the Forceware 90 series of its drivers will enable the second card in an SLI configuration to handle physics calculations based on the Havok FX physics engine as well. While Ageia's method is supposed to transfer completed object calculation tasks to the CPU, Nvidia's SLI approach is only supposed to render visual physics effects. If this comparative description sounds noncommittal on our part, that's because there are some caveats associated with the solutions of both vendors. The first concerns Ageia. In the showcase game Ghost Recon, the player cannot manipulate the objects. The additional debris and splinters the Ageia hardware renders disappear shortly after the explosion. The second caveat involves Nvidia. The new Forceware 90 driver has to be freely available before SLI-rendered physics can be tested. Some rumors say this won't be the case until the end of July. Only then will we be able to judge what advantages Nvidia's solution offers in practice, if any. Also, it remains to be seen whether this solution will work with any Havok FX-based game or if games will need to be subsequently coded or patched to take advantage of the physics calculations.

At any rate, direct comparisons between the two solutions will be difficult, as it is entirely possible that there won't be any games that support both solutions. Already, while Ageia uses its own PhysX engine, Nvidia is opting for Havok FX, which is not yet released in any games. Ageia's engine made its debut in Ghost Recon Advanced Warfighter. Players will make first contact with the engine during the installation of the game, when it insists on installing the Ageia hardware driver, regardless of whether or not a PhysX card is present on the system. Since the dialog box only has an okay button, there is no way to stop the driver's installation. The reason for this installation are the effects physics based on the Ageia PhysX SDK (Software Developers Kit). The hardware card is the same as the software rendition - only wired into hardware. The future will show whether PhysX and Havok FX will be compatible. However, it seems unlikely that game developers will be willing to pay licensing fees for both engines.

The third approach we mentioned above was using the CPU for physics calculations. Presently, opinions differ on whether this is a feasible solution. While one camp asks why the second core of a dual-core processor should not be able to handle the physics calculations, the other maintains an all-purpose processor would be far slower for such a task than a specialized chip such as Ageia's PPU. However, there is good reason to be skeptical about the pretensions of PPU backers, since games like Oblivion and Half Life 2 already prove that a software implementation on a CPU is able to deliver first-class physics effects, too. Also, what value will quad-core CPUs offer for games that instead rely on PPU devices for physics calculations?

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