OXCGN – Breathing Life Into Gaming

by AXIS of Reality

©2009 Alex Baldwin

Cast your mind back to 2003. Remember seeing those amazing E3 videos of Half-Life 2 with a Combine gunship shooting a car the player was hiding behind?

You know, where the doors would swing and the whole car would lurch on its suspension under the impact.

It was at that time that the buzz was officially started for the so-called physics revolution.

Yet here we are 6 years later, with fancy schmancy new hardware (360/PS3) and what is there to show for 6 years of tech exponentially improving in game physics?

For the most part, just a few more boxes that can fall off shelves. Yay.

It’s with that in mind that I’m going to have a close examination of where we are at the moment and why, since it’s one of the key elements of games next to graphics, sound and gameplay.

First, time to go even further back to the late 1990s when Dreamworks was working on a PC game known as Jurassic Park: Trespasser. This was a title being prepped to turn what people expected from games on its head.

• Jurassic Park: Trespasser demo

Instead of controlling a camera with a gun strapped to it poking out the right-hand side of the screen as most FPS do, you would actually have control of in-game hands.

Pick up in-game objects to use, all physically accurate and all dynamic to use against the evil dinosaurs (a game enemy that seems to have ironically gone extinct since Turok).

Pretty impressive for the age of the PSX and N64, yes? So why haven’t you heard of it along with other landmark titles like Half-Life and Mario 64?

Time to execute

Unfortunately Trespasser can be attributed with damning the use of physics in games for years.

Simply put, it was broken. Horribly, horribly broken. Everything was glitchy and bugged, making everything with ‘physics’ appear to just be acting randomly.

Because the physics didn’t work, the game didn’t work. And after all, what designer wants his/her game to be destroyed through no fault of their own simply because the technology just isn’t there?

• Half Life 2 at E3 03

After Trespasser sank into oblivion, nothing much was heard of game physics or ‘dynamics’ until Half-Life 2‘s first trailer and the release of Deus Ex 2: Invisible War.

Possibly the first large commercial release with properly working physics (provided by the soon-to-be industry standard providers, Havok), Invisible War let the player pick up any object (or corpse) not bolted down and throw it around.

Admittedly it was in the early days so boxes and human corpses seemed to weigh the same but hey, the physics worked.

You knock out a guard, pick him up and stick him on a bonfire to watch him wake up screaming (and then die). Entertaining stuff.

However it wasn’t until 2004 that game dynamics started to become common and feasible for developers.

Halo 2 and Max Payne 2 both used Havok to great effect to make shooting enemies that much more entertaining – after all, who wants to watch the same death animation over and over when they could see a body slump down in a heap or fall over the edge of a cliff?

Crates went flying from explosions, lights would swing and all-in-all it was a much more dynamic experience.

No more static environments

Environments weren’t static anymore – they were part of the action.

It must be said though that Half-Life 2 really set things in motion – literally. Using a modified version of Havok in their Source Engine, Valve showed its use in gameplay with physics puzzles utilising one of the most brilliant weapons ever: the physics gun. Run out of ammo?

Just rip a toilet out of the wall and hammer your opponent’s urinals. Good times…

Soon after, the rumour mills were grinding into action about new games with grenades that would blast holes in the ground, weapons that could blow open the sides of buildings and vehicles that could be smashed and destroyed piece by piece. Lofty expectations indeed, which were further fueled by a newcomer to the scene: Ageia.

Developers of the PhysX game dynamics engine (brand new at the time), Ageia suddenly released a unique piece of PC hardware, a physics processor (PPU).

It worked much like a graphics processor (GPU), but instead was dedicated solely to accelerating physics calculations to allow the generation of game dynamics on a scale that was never before possible on a regular processor (CPU).

This was attributed to its use of parallel processing. Each core on a regular processor can only perform once calculation at a time, so if there’s something like barrels being thrown away from an explosion it needs to queue up the calculation of where each point on each barrel should be in the next frame from the game’s physical rules.

This is all well and good if it can be done before the next frame is rendered at 30 or 60 frames per second, but what happens if there’s too much to calculate for a processor not fast enough to do it before the next frame is due? The framerate drops and ‘chugs’, as can be seen quite commonly in games such as Half-Life 2 for the split second after shooting an explosive barrel.

While dual-core and quad-core processors have alleviated this to a certain extent, there is a lot of room to improve.

The Xbox 360′s tri-core Xenon CPU has 6 effective threads (2 per core) which can theoretically allow these calculations to be performed up to 6 times faster than a standard single-core CPU providing it’s not doing anything else at all on the CPU at that time (such as AI, sound, etc) which is very rare.

The PS3′s Cell CPU fares a bit better with 7 effective streams (8th stream is locked) and is designed for extreme parallel processing, but still far from ideal when the CPU is in demand by other game elements.

The Ageia PhysX promised to fix this by using massive amounts of parallel processing (but at a slower speed per core) which is ideal for physics, and it succeeded.

However, unless there’s a significant market penetration developers won’t have a real chance to utilise it.

After all, if a game can sell 1 million copies on PC, what happens if only 1 in 20 people own a PhysX card? Sales are reduced to 50,000. Not attractive at all.

Instead, the developers that did use the card simply offloaded regular game physics to it that a CPU could easily handle, raising the framerate as the CPU is freed up for other tasks but not changing the gameplay in any significant manner at all.

The PhysX card was relegated to just an expensive way to get an extra 5 or 10 frames a second in certain games.

Illusive PhysX exclusive

There was only one PhysX-exclusive game ever developed, and really it was just a tech demo.

Cellfactor and it’s ‘sequel’ Cellfactor: Revolution let you destroy pretty much everything including tearing cloth and causing massive explosions with debris raining down that was extremely impressive but in the end nothing more than something to ‘ooh’ and ‘aah’ at, then get back to playing UT2004.

Still, Ageia did prompt Havok to up its game. No longer was Havok sitting easy as king of physics engines, and unless they did something fast Ageia could steal a large chunk of their clients as PhysX could also work as a regular CPU-run dynamics engine.

Hence, there was the much publicised Havok FX unveiled by Nvidia and Havok. Instead of running gameplay physics such as characters and objects, Havok FX would run ‘environment physics’. This translated into more superficial physics use such as making accurately moving snow or waves in water. Basically, prettying up your game.

The most significant aspect though was that this would run on the console or PC’s GPU. No extra hardware would be needed, as the GPU on modern graphics cards work similar to Ageia’s PhysX card – using extreme parallel processing. ATi also took the opportunity to boast that their new flagship GPU (the X1900) could run physics many times faster than Ageia’s ill-fated dedicated card.

Despite Havok’s insistence that many developers were already working with Havok FX and the first games with it were right around the corner, it soon sank into nothingness never to be heard of again.

This may be because of two major events.

First, Intel announced its purchase of Havok. This made sense as physics are traditionally run off the CPU which Intel specialises in. It was also around this time that Havok FX’s other partner Nvidia split ways, unveiling their complete purchase of Ageia including their PhysX technology.

Not long after, Nvidia made the move that may define the future of game physics: Ageia’s PhysX technology would be run off their GPUs at faster speeds than even Ageia’s dedicated card. Nothing extra to buy, and able to be unlocked in a driver update for Nvidia’s already released GeForce 8 series and above as it runs off Nvidia’s CUDA programming interface to design applications for their GPUs.

Ageia’s launch impact

This made more of an impact than Ageia’s card launch, as Nvidia is the largest GPU supplier in the world with approximately 65% market share.

Games such as Unreal Tournament 3, Prince of Persia 2008 and Mirror’s Edge using the PhysX engine could have their physics accelerated on Nvidia’s PC GPUs and as such some had PhysX-exclusive add-ons.

Mirror’s Edge added dynamic ripping cloth and accurate glass to GeForce owners while UT3 had 3 extra maps utilising the increased physics processing allowing effects such as accurate hail and even tornados moving through levels ripping up objects as you play.

The regular games are playable on all PCs (and consoles, where applicable), but some PhysX extras gave bonuses to Nvidia users. Upcoming games such as Dragon Age: Origins and Heavy Rain also use PhysX.

Modders also revealed that if the PhysX programming was simply ported to the new unified language OpenCL that works on all modern GPUs it could work just as well on ATi’s hardware.

However, Nvidia owns the tech and there’s little chance ATi would ever want to pay their arch-rivals to license that tech. Instead, ATi and Havok revealed at GDC 2009 that they had Havok’s new product Havok Cloth running on ATi’s 4000 series GPUs at dozens of times the speed a CPU could handle.

Better yet, it was being developed in OpenCL so ALL modern GPUs had the ability to use it. This is a much more attractive proposition than one such as PhysX that is only available to one segment of the market for developers.

Hope is always there

It’s unclear whether this is possible on the Xbox 360 GPU (from ATi) or the PS3′s RSX GPU (from Nvidia), but we hope there’s a way.

All in all, it looks like we’re finally on the verge of having physics fast enough to be a significant element of the gameplay. While Red Faction: Guerilla and Force Unleashed had impressive destruction, imagine the possibilities with dozens of times more physics processing power.

While other engines such as Euphoria and Digital Molecular Matter have shown additional uses for physics in dynamic character animation or breaking materials uniquely they haven’t had a real chance to shine as CPU speed has held then back.

After all the side-switching of Nvidia leaving Havok for PhysX, and ATi partnering with Havok despite being owned by Intel which is ATi’s parent AMD‘s rival in the CPU business (confused yet?) we might finally get some progress on the physics front.

It might not materialise fully this generation, but one thing is certain: physics on the GPU is the future.

And hey, if we know Valve it will probably time with Half-Life 3′s release.

©2009 Alex Baldwin

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Filed under: Console gaming, Editorial, Game Industry News, GameBanter, Hardware News, Industry News, Xbox 360 Tagged: | ageia, ageia physx, amd, ati, deus ex 2, deus ex: invisible war, DICE, Digital Illusions, Dragon Age: Origins, Dreamworks, EA, Electronic Arts, game dynamics, game physics, Half life 2, Half Life 3, havok, hl2, hl3, intel, Max Payne 2, Mirror's Edge, N64, nvidia, PC, physx, Prince of persia, PS3, PSX, source engine, UT3, Valve, Xbox 360