A Closer Look At PhysX: Our Take On The PPU

Final Words

To sum up what the hardware will offer consumers at the outset, here’s what we are looking at: 32000 rigid body objects, soft body objects, fluids, particle systems (40-50 thousand particles), and collision detections. The end result will range from cooler special effects in games (explosions, cloth-like clothing, and massive particle systems) to totally interactive environments (where anything and everything can be pushed, pulled, thrown or otherwise destroyed in a realistic way).

Currently, rather than a direct hardware API, the features of the PPU will be accessed via the NovodeX SDK. This physics engine was bought by AGEIA and built to use either software physics simulation or the PhysX hardware. This gives developers some flexibility to develop software that works with or without the hardware.

AGEIA would like to have hardware support from other SDKs, but currently only their in house engine adds hardware support. Of course, there are already some games that are built using NovodeX. And more are coming. Epic and Ubisoft (among others) announced that they will be using NovodeX and building in support for hardware accelerated physics through the PhysX PPU. With future Unreal Engine 3 and Ubisoft games supporting a PPU, AGEIA has a good start ahead of them.

The hardware itself is a 125 million transistor chip built on TSMC’s 130nm process. All we know about architecture is that it’s built with lots of data moving capability by networking experts. They’ve got parallel floating point hardware connected internally and externally to lots of bandwidth. The architecture is inherently different from that of current CPUs or a GPU.

We say it’s different than current CPUs because it’s possible that someone could integrate application specific physics hardware onto a CPU in the future. At the same time, there is one architecture on the horizon that could fit physics better than Intel’s approach: Cell. The fact that SPEs are able to access each other’s local stores means that (depending on internal bus availability) sharing data between parallel tasks will be much easier. We will have to wait for more architectural details of PhysX and Cell to leak out before we can tell how good one is with respect to the other (for physics processing).

Consumer acceptance is key to the success of the PPU. And in order for people to accept the product, we will need to see other physics engine support (Havok would be nice) and, ultimately, games. In this case, people won’t be interested unless game developers embrace the hardware. Hopefully developers will see the potential in added physics power and will embrace the product for its ability to make their games better.

Right now, AGEIA is talking about pricing on the order of graphics card. They aren’t sure of cost right now, but they could introduce multiple SKUs that fit different price points and have different processing power. It is more likely that we’ll see one part come to the market place. If the PPU flies, we might see more variety.

At first, we can’t expect a new genre of incredibly interactive games. The first few games that adopt the PPU will tack it on like the first few games that embraced hardware 3D. We’ll start by seeing effects enhancement (like more particles and objects go flying from explosions or some objects may get an upgrade to being deformable). If AGEIA has it their way, we will start seeing motherboards and notebooks integrating the PPU. If they can get good integration and acceptance of their add-in card, we might start seeing games that require a PPU and are really revolutionary with the level of user interaction allowed. AGEIA really wants to mirror the revolution that occurred with 3dfx, but it may be a better idea for them to separate themselves from that image considering how hard 3dfx fell from power.

Many people don’t think a separate add-in PPU will fly. What about vendors dropping both the GPU and PPU on one card? Maybe if the add-in PPU doesn’t stick around, we will one day see the birth of a ubiquitous “gaming card” that integrates graphics, physics, and sound onto one add-in board. Or if Intel decides that they need to go the extreme route, we may see integration of very application specific hardware that can handle tasks like physics processing onto the CPU.

We like the idea of the PPU a lot. But like plasma television (which has been around for decades), just because good technology exists doesn’t mean vendors and consumers will adopt it. We hope PhysX or something like it leaves a lasting mark on the PC industry. As unpredictable as they are, it’s about time we had another revolution in game design.