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Batman: Arkham Asylum PhysX Features and Performance October 06, 2009 Jacob Vandy |
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Summary: One eye candy feature PC users can enjoy over the console edition of Batman: AA is PhysX. Rocksteady's PhysX implementation is more than just tearing cloth and added objects too, although that's of course in there. Vandy goes over the features and performance of PhysX in Batman: AA in this article!
 Introduction | Page:: ( 1 / 4 ) |
Unfortunately, the dedicated PPU garnered very little support from developers; they didn’t want to spend the extra time and money to make use of something that practically nobody had in their PCs. Nor did gamers want to buy extra hardware when there were no games to use it with. Everyone seemed to be content with what could be done on the CPU through software like Havok. On top of that catch-22, industry heavy-hitters ATI and NVIDIA soon announced their own hardware physics solutions. The obstacles Ageia faced were simply too much to overcome, and their PPU failed to take off.
All of that changed in 2008, when NVIDIA decided to buy out Ageia and inherited PhysX. They ditched the standalone PPU idea, instead adapting the technology to use GPU power to fuel PhysX effects. Now, any GeForce 8-series and above could be utilized to accommodate physics effects. Not to mention, if you have an SLI-capable motherboard, you can even dedicate an extra video card you have lying around to performing PPU operations.
Many games have used the PhysX engine in the past few years, but now we’re beginning to see AAA title releases that take advantage of PhysX hardware acceleration. Ageia dreamed of such a day, but it simply would not have been possible without the backing of a major company with a pre-established name and market share. Rocksteady Studios worked closely with NVIDIA to bring PhysX effects to their newest game, Batman: Arkham Asylum. We’ll be taking a closer look at some of the fancy new visuals that are exclusive to the PC version, as well as a few performance tests.
| PhysX Effects | Page:: ( 2 / 4 ) |
Advanced cloth simulations are responsible for many of the PhysX effects in the game. Banners and flags flutter and sway, shredding when a Batarang or gun fire hits. Caution tape and cobwebs tear as Batman moves through them. Sheets of paper are strewn about the floors throughout Arkham interiors. They furl and roll around in reaction to characters kicking them. During combat, Batman’s swift movements cause them to fly into the air and float back down again. Without PhysX, they only exist as static piles and textures stuck onto surfaces. On the outside, fallen leaves act in much the same way, adding to the appearance of your interactions with the game world.
Volumetric smoke, steam, and fog generated by PhysX are much like the effect introduced with Shader Model 3.0/DirectX 10 and seen in games such as STALKER: Clear Sky. The whole point is to be rid of the two-dimensional sprites that form crude imitations and don’t react at all to their surroundings, clipping through objects or the boundaries of the level itself. NVIDIA PhysX treats smoke as an actual object that takes up space and is contained in the game world. It moves around somewhat like a liquid, if the droplets were the size of softballs. This is called smoothed particle hydrodynamics and allows smoke to directly interact with not only the environment, but characters, as well.
Most games employ only basic physics on a few things like boxes or barrels, maybe bodies and other various items. Objects are given properties that allow them to be subjected to forces like gravity and explosions. Beyond that, the game also needs to be able to know if two objects are touching so that it might make corrections to ensure they don’t break the laws of physics by occupying the same space. This is known as collision detection, a quite complicated and resource-draining operation, and is the extent of most software-based physics.
Having a lot of so-called rigid bodies in a scene will put a strain on the CPU because of all the calculations that need to be done to make sure they behave properly. This can be solved with the hardware acceleration provided by NVIDIA GPUs. Some scenes in Batman: AA involve hundreds or even thousands of dynamic objects on screen at once, something that previously could not even be conceived! It will bring your framerate down quite a bit even now, but chips get more powerful and algorithms are improved, so it’s exciting to see what can be done with this technology in future games.
| Test Setup | Page:: ( 3 / 4 ) |
NVIDIA GeForce GTX 275 896MB / GeForce 8800 GTS 512MB (G92)
4GB DDR2-800 RAM
Windows 7 Ultimate RTM 64-bit (ForceWare 191.07)
The in-game benchmark was used with a few different configurations. First, the 8800 GTS by itself, then the GTX 275 by itself, and finally the GTX 275 used for graphics and the 8800 GTS dedicated to physics. Tests were run with the following settings:
| Batman PhysX Performance | |||
| 1680x1050 resolution, 0xAA, Very High Graphics Settings | |||
| Card | PhysX Off | Normal PhysX Setting | High PhysX Setting |
| GeForce 8800 GTS 512 | 91 | 42 | 35 |
| GeForce GTX 275 | 119 | 55 | 46 |
| GeForce GTX 275 + 8800 GTS 512 | 120 | 66 | 59 |
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Notes
With PhysX off, you get only the most basic physics, equal to what is present in the console versions of the game. As expected, the GTX 275 is substantially faster than the 8800 GTS, and the dual setup netted no performance gain without PhysX effects enabled.
The Normal setting brings volumetric smoke/fog and dynamic debris like papers and leaves, but sees each number reduced by about half. The same margin between the 8800 GTS and GTX 275 exists as with PhysX turned off. A very respectable 20% is gained with one GPU dedicated to physics calculations.
Framerates are reduced further when the PhysX are turned to High, as realistic cloth effects beyond the cape are added and smoke/debris are further refined. The individual scores maintain the identical proportion seen in previous tests, but the really interesting part is with the pair’s result. The increase in performance brought by the dedicated 8800 GTS is even greater on the High setting than on Normal, coming to about 28%.
Comparing these results to the official recommendations (GTX 260 for Normal and GTX 260 + 9800 GTX for High), it becomes apparent that they are on the conservative side. Depending on what you think is a playable framerate, you could pull off High PhysX for the most part with a mid-range 8-series video card.
| Conclusion | Page:: ( 4 / 4 ) |
In any case, we’ve seen many of the PhysX effects in Batman: AA in previous PhysX titles that have debuted over the past few years. Eye candy PhysX features like cloth simulation and volumetric smoke/fog are nice additions that really up the immersion factor, but it’s the addition of rigid bodies that really sets Batman: AA apart from previous PhysX titles like Mirror’s Edge. You can really see this in the scarecrow levels where entire walls can be blown up into hundreds of pieces.
We’re still nowhere near the point of fully destructible levels like you see in Warmonger, but Batman: AA is evidence that more realistic physics employed as a visual treat are coming along quite nicely.
When will it become more than that though? Why not apply hardware-accelerated PhysX to a game like Red Faction: Guerrilla, with its huge destructible buildings that inevitably slow your game down to a crawl? Certainly you could even open it up to deforming terrain, something that has been sorely missed since the original Red Faction. I would gladly give up some graphical detail in exchange for gameplay that involves hyper-realistic physics in a way that isn’t too gimmicky.
In my opinion, it’s doubtful we’ll see fully destructible environments in games until developers begin to target DirectX 11 and DirectCompute as the minimum hardware spec. It wouldn’t surprise me if that doesn’t occur until a year or so after the next console refresh (PS4, Xbox 720, etc), so that could be 2012-2014 timeframe depending on when the consoles arrive – Brandon
Fancy-schmancy PhysX effects might push those of you with enough GeForce power under the hood to buy it for PC, even if you’ve already played it on a console. Unlike 3D Vision, it doesn’t require you to buy several hundred dollars worth of equipment to enjoy it, either. It’s just a nice little bonus from your friends at NVIDIA. On the other hand, Radeon users are SOL, and I can’t recommend you jump on-board unless you’ve not played it before. Ultimately, the excellent gameplay offered by Arkham Asylum is not affected much at all when PhysX is out of the picture.