Bodies in Motion

PC Hardware | Monday, April 24th, 2006 | 10 years, 11 months ago

A recent Slashdot article on my favourite whipping boy, Oblivion, has gotten me thinking about the hot-off-the-presses Ageia PhysX (site down at time of posting) physics processing unit (PPU). In my comment on the topic I make the unprecedented move of defending the topic with my argument, quoting several areas in the game that are cliches of single player CRPGs that could be improved with this revolutionary new technology.

The Ageia PhysX is a CPU on a riser expansion card that is dedicated to processing 3D world physics – mass, viscosity, friction, malleability, flexibility, fragility, and all-round explodability.

But let’s back up a little first.

Lifelike physical behaviour of game worlds is something we gamers have been trained to take with a grain of salt. In most games, world physics haven’t evolved much at all since Qbert hopped onto the scene, one cube at a time. Most of the world is absolutely static and unflinching, as if every object was nailed down to the one below it, while select items have simulated but scripted lifelike properties. For instance, you might be able to push around and pick up a book on a desk, but a bookshelf is just an unmovable elongated cube with wood and books painted on for effect.

To some extent this design shortcut is the product of laziness – time is money, and it takes a lot of both to assign weight, density, and other properties to every single item in a game world. Even if this feat were feasible, modern CPUs would have a very difficult time calculating the interplay of objects while still presenting the game onscreen in a timely, smooth, playable fashion. Not every game can afford to be a newtonian masterpiece, nor do they need to be to steer the player to the end of each level. However, physics as superfluous eye candy has always been welcome.

Some games classified comfortably in the “retro” category do a great job of emulating realistic physics while keeping the CPU free for more mission-critical calculations. For instance, missile weapons and many interactive objects had weight and velocity constraints in the first-person CRPG Ultima Underworld: The Stygian Abyss (fun fact – the physics were programmed by pere du Xbox Seamus Blackley). The game’s immersion factor, which may seem laughable by today’s standards, was unparalleled due to little touches like these, drawing the player head over heels into the subterranean unknown beneath the land of Brittania (as occurs literally in the Ultima games). Make no mistake – Ultima Underworld was Oblivion before the Pentium days.

Game designers took note of gamers’ acclaim of such immersive worlds, and physics became adopted more and more into gameplay. Full blown physics simulators such as flight and driving sims became far more realistic and challenging with the introduction of dynamic wind, weather, temperature, and craft damage. Makers of games in other genres took notice as well, showcasing experiments in gameplay such as the destructable environments of Red Faction 2 and the exhilirating physics puzzles of Half Life 2.

Which brings us to today. Ageia, a company we’ve never heard of, wants to convince us that a $250 PCI or PCI-Express 4x expansion card will enrich our gaming experience beyond our wildest dreams. That’s a rather hefty price tag to peg on a technology that will only be supported by 5-15 titles on or around launch. Of course, this situation is very similar to that of a little company called 3DFX, makers of the first 3D-accelerated video cards, and we’ve all got one (or two) of those in our systems these days.

So what can PhysX bring to the table? Ageia founders Manju Hedge and Curtis Davis shed some light on this technology:

The Physics Processing Unit (PPU) is a dedicated processing unit that was built from the ground up to accelerate the algorithms required for physically based simulations. This includes things such as Rigid Body Dynamics, Collision Detection, Fluid Simulation, Soft Bodies and Fracturing of objects. It will revolutionize your CPU/GPU system by unlocking the potential of the system by allowing each of the processing components to do what is best at. The PPU makes the games move and interact! We are really bridging the gap between the visual appearances and the movement of games that should go along with the graphics of today.

A high-level summary, but it succeeds in whetting some nerdy appetites! With CPUs branching into the realm of dual and multi-core designs, dedicating processors to tasks seems to be the wave of the future. This is interesting to see, as servers have recently evolved in the opposite direction with virtualization, running multiple operating systems simultaneously on a single computer.

This idea could flourish or fizzle depending on the strength of technical and marketing muscle, and could have wide-reaching ramifications for PC design in the future. For instance, perhaps PCs of the future will forgo the powerful CPU entirely, dedicating individual tasks to RISC (reduced instruction set computer) chips that excel at one or few specific tasks. Enthusiast products like Sound Blaster’s X-fi sound card platform already take advantage of dedicated processors to offset CPU load.

But these technicalities are pretty dry and meaningless for the average consumer. Nobody’s going to open up their computers to plug in a $250 administrative assistant for their CPUs without some coercing in the razzle dazzle department. This is the area of debate, as it was with 3DFX, and will make or break this venture.

As physics enhance moving demos but don’t do much for static screenshots, the onus is on Ageia to provide many high quality video demos such as this one in order to entice prospective customers. Cell Factor is a multiplayer deathmatch shooter akin to Quake 3 whose environments are littered with movable and destructable objects. Smacking these objects around with gunfire and flailing corpses will constantly reshape the arena, forcing players to adjust strategies on the fly and bend the landscape to their advantage. Strategy isn’t illustrated very will in this video clip, but the eyecandy certainly causes some sugary pupil caveties!

Cell Factor is definitely how I pictured launch titles for this technology – zillions of cubes and pyramids flying all over the place like a commercial for the new Batmobile shooting its missiles at those uber-cool pyramids of icecubey blocks. I don’t find this implementation particularly interesting. I want to see this processor chugging subtley behind the scenes.

I started thinking about PhysX while watching a Stanley Cup game the other day. One burly gentleman gave an opponent a nasty lesson in physics with his shoulder and hip, sending his adversary to the ice barely in one piece. The commentators remarked at how this crushing hit could have been absorbed by the larger recipient if he had kept his head up and compensated by shifting his weight. “YES,” I thought to myself, “this is precisely what I want to see in PC hockey games!” Animating 12 players and a few refs on a static playfield must be child’s play for a powerful PPU. The same goes for a basketball game, cars on a track, planes in the sky, or the rippling gelatinous masses of two sumo wrestlers! I’m not much of a sports fan, but this technology makes me excited about the very fundamentals that make these sports challenging in the real world.

I’m also interested in the prospect of objects decomposing and splitting realistically. Half Life 2 did a lovely job of simulating this, as acquiring my crowbar and going to town on some wooden planks near the start of the game was a giddy and gorgeous prelude of things to come! Just imagine HL2’s gravity gun in a physics-enhanced environment! Firing a cement brick at a car would result in the front 2/3 of the brick pulverizing into powder, denting the thin car exterior and wrapping the roof around the internal roll cage, causing the vehicle to sway slightly and displace the sand beneath in a concave divet.

Of course, the game will have to be written to specifically take advantage of this hardware. Some developers are enthusiastic about this technology, but others are pessimistic. Says Kevin Stephens of Monolith Studios, makers of horror shooter and physics playground F.E.A.R.:

“To be honest I don’t think gamers will spend money for dedicated physics hardware (unless it’s included in something they already buy like their video card) so I’m not sure if this will ever catch on…

However, if dedicated physics hardware could be guaranteed the improvement to the physics realism in games would be incredible.”

I reiterate; the success of this evolutionary and powerful technology is dependent almost entirely on the strength of its launch lineup, the silverness of its PR tongue, and of course the body count of its first killer app. Ageia will really have to hit the pavement to prove the worth of their little miracle, as its benefits are entirely unapparent in static screenshots.

Will the PhysX card usher in a new era of realism in realtime computer animation? Is Ageia the next 3DFX or is it doomed to be the next Virtual Boy? Please leave a comment and share your opinions!

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