id Software’s John Carmack gave Ageia some physics action—in the form of turbulence—when he told bootdaily.com that he is “…not a believer in dedicated PPUs.” But it looks as though neither Valve nor Crytek—developers of two other important game engines—are prepared to join the PhysX faithful, either.
The limited installed base of PhysX cards is one of the biggest hurdles for Valve. “We all hate cliché’s,” says Valve’s director of marketing, Doug Lombardi, “but it’s the chicken-or-the-egg problem. The current designs for a PPU (physics-processing unit) offer some advantages in what can be achieved technically. But there’s a bigger question mark with respect to adoption rate, and that has a real-world impact on how many games support them.”
Asus and BFG are the only hardware manufacuters offering PhysX cards today.
Crytek’s Cevat Yerli, executive producer and director of Crysis, points out another problem with supporting a physics processor: The need to create a gaming experience that’s different enough from what’s possible on mainstream hardware to justify the gamer’s investment in the hardware without making an entirely different game for the majority of gamers who don’t have the hardware.
In an interview with Maximum PC’s editor-in-chief Will Smith, for an October issue cover story, Yerli says “We are not supporting GPU or dedicated physics processors for a variety of reasons. The main one is that we did not want to change the core gameplay physics for our min-spec configurations. We have been optimizing our dynamics code for many years now, so it can run robust and as optimally as it can on CPUs of previous generations while also taking advantage of newer multi-core architectures. So you are best equipped with a quad core—if you have the budget—but Crysis will do great on dual-core configurations as well.”
Ageia’s executives, meanwhile, argue that the best hardware for accelerating physics is a processor specifically designed for that application. As Ageia’s vice president of marketing, Michael Steele, puts it: “A truly large-scale physics solution that enables developers to add lots of physically simulated primitives into their games requires hardware that is massively multi-core—we’re talking tens to hundreds of cores. It takes high amounts of floating-point throughput, on par with the [IBM/Sony/Toshiba] Cell processor. It takes highly independent processing to handle the irregular nature of physics—GPUs don’t have this. And it takes high amounts of memory bandwidth—CPUs don’t have this.”
CPU cores have been designed to each execute single-thread programs as fast as possible, and their cache systems are optimized for such operations. The AGEIA PhysX processor has been designed to optimize the execution of many parallel threads of mixed integer and floating-point operations with high entropy data access. On so many dimensions, multi-core CPUs fall short.”
Valve’s Lombardi doesn’t necessarily disagree with Steel’s views, allowing that “…the current designs for a PPU offer some advantages in what can be achieved technically.” And as he points out, physics helped move lot of copies of Half-Life 2. “Players told us with their dollars that this was an important move forward,” says Lombardi. “Subsequently, we’re investing to expand the physics simulation systems of the Source engine and are always evaluating the scope of hardware that will best bring these experiences to life.”
But we gather that PhysX won’t be within that scope in the near future, because as Lombardi points out, other alternatives—primarily multi-core CPUs—already enjoy more market- and mindshare: “When the GPU was the big new idea, it just wasn’t possible to achieve what Mr. Carmack did with GL Quake and what others were doing to pioneer advanced graphics via any of the existing pieces of the PC of that era,” says Lombardi. “Physics routines such as those in Half-Life 2 were achieved in 2004 on millions of non-PPU enabled PCs. Today, multi-core CPUs are opening the door for advanced AI, advanced physics, wildly faster performance, and more—and it’s shipping in just about every new PC being made.”
Does this lack of key developer support spell doom for Ageia? Not necessarily. After all, they still have Epic Games’ Unreal Engine 3 in their corner. All they need now is that one killer app that will make everyone a believer. As Lombardi puts it “It’s going to require something truly wicked that’s only possible on a PPU to move customers and developers to it.”