Getting Physical: AMD, NVIDIA Trade Shots Over Hardware Physics

When it comes to hardware-accelerated PhysX and the future of GPGPU computing AMD and NVIDIA are the modern-day descendents of the Hatfields and McCoys. Both companies attended GDC last week, where a completely predictable war broke out over PhysX, physics, developer payoffs, and gamer interest in PhysX (or the lack thereof).

The brouhaha kicked off with comments from the senior manager of developer relations at AMD, Richard Huddy, who said: "What I’ve seen with physics, or PhysX rather, is that Nvidia create a marketing deal with a title, and then as part of that marketing deal, they have the right to go in and implement PhysX in the game...I’m not aware of any GPU-accelerated PhysX code which is there because the games developer wanted it with the exception of the Unreal stuff. I don’t know of any games company that’s actually said ‘you know what, I really want GPU-accelerated PhysX, I’d like to tie myself to Nvidia and that sounds like a great plan.'"

This rather irritated Team Green, who hit back with some comments of their own. In an interview with PCGamesHardware, the director of product management for PhysX, Nadeem Mohammed, said: "we do not pay developers to select PhysX instead of other physics solution. Once PhysX is selected...we will work closely with them [the developer] to provide whatever engineering and technical assistance to make the PC version as good as it can be—and hopefully that includes pushing the edge on special PhysX effects which may require GPU acceleration for best performance."

In Batman: Arkham Asylum, PhysX is used to create the fog and shadows above (along with some GPU cloth)

From here the situation declines rapidly. AMD claims that PhysX is proprietary, deliberately deprecated to lower CPU performance, and that NVIDIA's claims that gamers actually want PhysX are spurious. According to Team Red, NVIDIA is propping up PhysX through marketing deals and bribes; the company points to NVIDIA's decision to disable PhysX if a non-NVIDIA GPU is present and the squabble over antialiasing in Batman: Arkham Asylum as proof that NVIDIA can't be trusted to maintain an "open" standard. NVIDIA's response? bullsh err, "Nonsense." We don't have room to address the complete scope of the disagreement, but lets examine whether or not PhysX counts as proprietary.

Without PhysX, the game looks more like this. Detail levels are just as good, but the ambient fog and cloth are missing.

This Section Brought To You By Ragdoll Physics

PhysX is free in the sense that anyone can download the developer tools but it's not an open standard, despite NVIDIA's attempts to portray it as such. An open standard (like OpenGL) is typically maintained by a neutral third party or jointly controlled by several competitors.  NVIDIA has made comments implying that it would love to see ATI implement PhysX support in-driver, but AMD's experience with standards controlled by its principle competitor (Intel) have probably left it deeply leery of such partnerships. It's all to easy to see NVIDIA agreeing to share its current PhysX implementation only to turn around and announce a new, NVIDIA GPU-required version of PhysX, hypothetically dubbed PhysX 2.0.

Unless NVIDIA agrees to share power or turns the standard over to a neutral third party AMD (probably) won't come to the table.Instead of a unified hardware physics platform, we'll likely have to deal with two competing solutions. NVIDIA has the advantage of having started much earlier, but a true open standard from AMD could gather developer support quickly.

NVIDIA pays lip service to the idea of sharing PhysX with AMD, but the company's decision last fall to disable PhysX if an AMD GPU was running as the primary display speaks much louder than any nice talk about sharing. It's never, ever a good idea to punish your customers by taking away product functionality that they actually paid for. The company claims compatibility issues and QA testing were the problem, which should mean that the option is plastered with WARNING stickers and "Use at Your Own Risk."

Until the dust settles, gamers can look forward to fractured standard support, forced incompatibility, and a whole lot of finger-pointing.We at Hot Hardware can't predict what hardware acceleration standard will win, but as gamers we all lose.

One last note. The popularity of PhysX changes depending on how you tally it. If we count games that use software PhysX then NVIDIA's claim that over 240 titles use PhysX is probably accurate. If we go by hardware accelerated PhysX, there are just 15 games on NVIDIA's own list. Title quality is hit-and-miss. Even if we assume there are 10 games that should be on that list and aren't, hardware PhysX support clearly hasn't taken off yet.

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