Nvidia announces SLI-accelerated physics

Posted by Humphrey Cheung

San Jose (CA) - Falling boulders, the ones that usually come crashing down on Indiana Jones, come with effects we expect to see in movies - but we typically cannot enjoy in video games. That is about to change. Physics is about to make its way into enthusiast computers: Nvidia's SLI physics will bring "thousands" of objects to life and realistically simulate how they interact with each other.

Physics simulation is a rare sight in video games today and an effect that is largely avoided by game designers. The behavior of independent particles - often many thousands created in scenes such as explosions or fluid dynamics - need enormous processing power to calculate the effects of their collisions.

In October of last year, ATI discussed the opportunity to use the massive floating point computation power of a graphics processor to enable accelerated physics - but Nvidia is first to introduce the feature to the market: Called "SLI Physics," the feature will offloads physics calculations from the CPU to the graphics processor and promises to bring movie-type effects from crashing cars and speeding bullets to the PC screen - all with smooth frame rates. A new software driver for Nvidia's graphics cards will use the second graphics processor to enable the feature in future games.

SLI Physics will be demonstrated for the first time in a technology demo at this week's Game Developer's Conference in San Jose and Nvidia promises to launch drivers thereafter.

As gamers demand more realism, physics is generally seen as the next evolution in video games and will be available much quicker than initially believed by analysts. Ageia's physics engine - the first physics technology to be announced and demonstrated on consumer PCs - was believed to be a niche market solution that would need many years to penetrate the market. And while Ageia will be hitting the market with a dedicated physics board later than expected, it has generated buzz, gained support - especially from Asus, BFG and Sony's Playstation 3 - and created a foundation for physics in the consumer market.

Both ATI and Nvidia have been quiet about their physics strategy in recent months. But with ATI's recent explanations around "dynamic load balancing" and Nvidia's SLI Physics, the direction has become clear: Multiple graphics processors provide plenty of excess floating point capability to run more than just graphics and overcome the limitations of the main processor of a computer system. Physics appears to be the first and major new application graphics chips will be aiming for.

Nvidia said that the new drivers will simulate object and particle effects like fluid, smoke and dust, all within the GPU. The data will stay on the graphics processor, a "transfer to the CPU will not be required," according to the company. While the name "SLI Physics" indicates that two graphics processors are needed to run physics, Nvidia officials told TG Daily that owners of single-GPU systems will still see "some benefit," but couldn't provide more detail at this time. Also, the company expects SLI physics to eventually enable "dynamic physics load balancing" via a desktop control panel interface, for owners of dual or quad GPU systems. The driver details are still being worked out, we were told.

So, how much faster is SLI Physics versus traditional CPU physics? We have to wait to get the driver - and supporting applications - into our hands to be able to judge the capability of the technology. Nvidia gave out some preliminary figures achieved in a demo that shows 15,000 boulders colliding with each other. The demo, aptly nicknamed "BoulderMark" was run by an SLI Physics enabled machine and GeForce 7900 GTX graphics cards with 64.5 frames per second while the CPU-only system topped out at out 6.2 frames per second.

Nvidia BoulderMark

Nvidia could be first to market with accelerated physics, but there will be more options to bring more realism to the desktop. Ageia - a company that licenses its physics technology to other companies - announced their PhysX physics processing unit (PPU) last year at GDC. Boards were promised to start selling Q3 of last year and are now scheduled to be available from manufacturers such as Asus and BFG in the second quarter of this year for prices between $100 and $400. Ageia's physics software currently has the advantage of having been available for some time, which allowed the technology to be integrated in several games such as Ghost Recon Advanced Warfighter and the Unreal Engine 3. Sony is also using the software in their upcoming PlayStation 3 console.

Nvidia provided only vague statements when asked about how SLI will compete against Ageia. "Having a dedicated processor for physics is a good thing. Ageia making physics the forefront is also a good thing," company representatives said. However, they also pointed out Nvidia's advantage in the market: More than six million SLI systems have been sold and dual-graphics systems are a common sight in the enthusiast market. Millions of installed video cards can be quickly converted to use SLI Physics as a result. The question is how quickly game developers will be reacting to the availability of SLI Physics.