It was a bit of a surprise to some of us in the tech world when nVidia decided to purchase Aegia. Apart from wondering why such a decision had been made there was the further query of exactly what nVidia was going to do with PhysX. Thanks to nVidia President and CEO, Jen-Hsun Huang, we now know the answer to the latter question namely that nVidia's plan is to "put the Ageia physics engine onto CUDA".
For those that don't know, CUDA (Compute Unified Device Architecture) is an SDK developed by nVidia which allows developers to run standard C code on the nVidia 8-series GPUs. nVidia has already talked about developing its own GPU-physics (as has, for the record, ATI/AMD) and was supposedly in talks with Havok about allowing its SDK to run via nVidia GPUs but since Havok is now owned by Intel, it seems unlikely that collaboration would continue.
Reworking Aegia's PhysX SDK to run via CUDA, then, means that nVidia is still using a physics engine that has already been proven to work (even if the hardware implementation was arguably somewhat lacking) and has a market share - albeit a much smaller one than Havok. From the consumer side things look much better for this implementation of PhysX too. nVidia has shipped more than 50 million CUDA-compatible GPUs (i.e. 8-series cards) to date, which makes the potential install base far larger than that of PhysX.
In the words of Huang: "I'm very enthusiastic about the work that we're doing here and the game developers are really excited about it," said Huang. "Finally they are able to get a physics engine accelerated into a very large population of gamers".
Quite how PhysX and CUDA are going to be tied together isn't known yet, nVidia's software engineers are only just working on the technicalities. Hopefully any 8-series GPU can be used to offload in-game physics using the new SDK, and an SLI setup wont be needed. Considering current PhysX cards cost in the region of £80, the idea of buying a £30-odd GeForce 8400 to run physics is much more attractive. All things told I'm becoming more and more intrigued as to how things are going to play out here and look forward to seeing just what nVidia can produce - fingers crossed it can make PhysX work.