Electronic Arts and Take-Two Interactive Software are adopting Nvidia's
PhysX technology, bringing more realistic gaming to the PC. The largest
graphics chip supplier announced this week that Electronic Arts and
Take-Two have licensed its PhysX technology as a development platform.
Nvidia got its physics technology when it acquired Ageia
in February. PhysX runs on the graphics processing unit, or GPU. Intel
and Advanced Micro Devices, on the other hand, have been promoting
technology that is executed on the central processing unit, or CPU.
Intel's approach uses technology from Havok, a developer of a physics
engine that Intel bought in September of 2007.
Adhering to the laws of physics
The goal of Nvidia's technology--based on the laws of physics--is to
make game objects respond in a realistic way to physical events. More
conventional technology uses a canned response, in which the same
motion is repeated over and over. For example, a window breaks or a
person falls the same way every time. In a PhysX-enabled football
sports game, however, the angle and velocity of the impact is
calculated by the GPU to generate a real-time response that is
different every time.
The technology was meant to run on the GPU, according to Jon Peddie,
whose firm tracks developments in the graphics chip industry. "It's a
GPU thing, and the fact that EA and Take-Two are coming out [with
support] gives you a clue why," Peddie said. "This really is a
significant event," he said, "enabling the GPU to do physics."
Ageia's secret sauce is its physics libraries, which are supported on
Microsoft's Xbox 360, Sony's PlayStation 3, Nintendo's Wii, as well as
on the CPU and Ageia's own PPU (physics processing unit), Ujesh Desai,
vice president of product marketing at Nvidia, said in an interview
last week. "It's a very open platform. Something game developers really
liked, which is why a lot of game developers adopted it," he said.
The launch pad for Ageia on the PC is Nvidia's CUDA, or Compute Unified
Device Architecture. CUDA already has a large installed base of GPUs
that can run a C program, "which is what PhysX is," Desai said. "We
bought Ageia, [and] they ported their PhysX API to our GPU, using our C
compiler on top of CUDA. So now there are 100 million GeForce [chips]
out there that can do PhysX processing."
And PhysX-enabled games will offer much greater realism.
"Today, the way they do sports games is motion capture. They capture
the different animation--running, falling," Desai said. "What you
realize is that for the first 5 to 10 minutes of the game (or movie),
it looks believable, but after you play for a while, you realize, wait
a minute, every time he falls, he falls the same way. Every time I make
that tackle, it looks the same."
The game Backbreaker
uses PhysX. "They're calculating those tackles in real time, based on
how the body interacts and the body mechanics interact. So no two
tackles are the same," according to Desai. Another game, Mirror's Edge,
is coming out for the PC in January from EA's Swedish studio DICE.
"Ageia changed the rules on this," Peddie said. "It's much, much more realistic."
Ageia's physics was originally done on an Ageia Physics Processing
Unit, Peddie said. "This was the only way to make it work. But now this
capability [software] has been ported to Nvidia GPUs, and this can be
done on Nvidia silicon," he said.
Physics can also be used to make things look more photo-realistic. "In
today's games, cloth and hair look very fake because you don't have the
right physical properties," Desai said. But with PhysX, "all these
things can be physically simulated."
Havok--the company Intel acquired--was the first to introduce physics
into games and bring out a physics library. Havok's physics has been
run on the CPU in a time-scheduled way, Peddie said. "Because of that,
there weren't many CPU resources to really do a great job on the
physics," he said. "Nothing would really happen. What happened, at
most, is that you would hit this thing (a window or a wall, for
example), and it would apply a decal to indicate that there was some
change in it. It's not very realistic."
AMD, for its part, will pursue a balanced platform. "The GPU is a great
place to do processing. We'll do the offloading [to the GPU], where it
makes sense," said Korhan Erenben, product marketing manager at AMD
Graphics Products Group. "[But] we are aligned with Havok, in terms of
working on a future direction of physics. Right now, it is on the CPU,
and we think that serves the broad installed base. Taking it to the
next step would be to have a capability on the GPU--where and when it
Physics is better on GPUs
Peddie explained why physics is
more suited for the GPU than the CPU. GPUs today typically have
hundreds of processors that are good at doing many things in parallel.
"If you have threads or processes that can be run simultaneously, [and]
if you have processors available to deal with each one of those
threads, then you can get your results a lot sooner," he said.
He described a technique called Same Instruction Multiple Data (SIMD).
"The same instruction is the physics equation. Things fall toward Earth
all the time. And the multiple data will be what the things are. It
might be a rock, might be a person, might be the wheel of a car. You
have to be able to process this stuff and have it behave in a realistic
fashion. To do that, you have to process it very quickly," Peddie said.
"The advantage that GPUs bring is that they have this humongous number
of processors. Certainly as good as the [Intel] 486 ever was. So
they're really good processors, and you've got hundreds of them
literally inside the GPU."
There will be challenges for users, however. "The tricky part
is, why would I want to take one graphics card and spend $500 on it,
and then not use it for graphics but rather use it for physics?" he
said. "The answer is, of course, I wouldn't." Peddie suggested that a
gamer might use the really good card for physics and employ the old
card "that you got last year" for graphics, assuming that there are
enough slots in the PC.
source : http://www.gamespot.com/