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PhysX SDK Support Comes Back To Linux

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  • Originally posted by mirv View Post
    Just so long as the physics is non-interactive (i.e eye candy) to a game, or some other application that doesn't require very high degrees of accuracy (such as industrial and/or scientific stuff), GPU is fine.
    Umm a GPU can be every bit as accurate as a CPU. In fact this is a key area for GPGPU. Accuracy of a GPU has never been in question. In fact Fermi based GPU's also follow the IEEE 754-2008 standard which is the exact same standard as CPU's. There is no "mythical property" that makes a CPU any more accurate. The "non-interactive" distinction is a bunch of bull as one of the whole ideas behind Physx is it's interactivity. The Physx effects are triggered by such interactive means.

    I'm just saying that there are some cases where the CPU is actually better suited for particular physics tasks,[/uote]

    The only place really where this would happen is on a very limited data set (read one particle at a time) with a very limited set of applied laws of physics applied to them where clock speed would become king. As soon as that data set becomes more complex the mass parallelism of GPU's start pulling away.

    even if the majority are much faster on a GPU, and even physx keeps some parts on the CPU rather than offload them (cloth physics does not fall under this category as far as I know).
    Sure Physx puts some less demanding tasks on the CPU, net result though is still that utilizing the GPU as well is a far more efficient means. Lets get one thing straight here, Physx has never claimed nor will it ever likely do so to be a 100% accurate model of applied physics. It has always been eyecandy and marketed as such. At best it could be use for "movie quality" physics. This is not a limitation by any means on the GPU. It is a limitation of being able to produce acceptable effects realtime for the end users enjoyment. You won't see Physx being used for intermolecular interaction fluid analysis as it was never intended to be as such. You can however have every bit as accurate of a model done on GPU with huge gains over a pure CPU setup again because of it's massive parallel capabilities vs the relatively small parallel capabilities of a CPU if you wish to take the time and code the more accurate equations into your application. Same results as CPU, just more of them calculated in the same period of time.

    This isn't just a limitation of Physx but also of Bullet, Havok, etc etc as they are not meant to be 100% real life interaction replication. They are all there for eye candy, nothing more, nothing less. It just happens to be a fact that as that eye candy gets more complex, LIKE the more accurate realworld interaction physics calculation applications out there, a GPU's massive amount of parallelism will thump a CPU pretty much every time if coded correctly.

    Physx is for gaming. Nothing more nothing less but a GPU isn't limited to Physx.


    • I was trying to separate game-physics from high-accuracy physics. Only recently has GPGPU been able to match CPU level accuracy - this is due to the floating point units of the hardware. GPU physics is not some magic that makes all & every physics calculation better, it's just highly suited to most of the algorithms (most, not all).
      Interactivity problems is not a bunch of bull as you seem to be forgetting one little detail: the data must be moved to and from the GPU. This takes time and is why gpu physics is mostly limited to eye-candy. If this wasn't an issue, then I assure you that CPU physics would be everywhere in games right now.
      There's also the issue of course of a GPU not being limited to physics - it was never designed for physics in the first place. It has to do (gosh) graphics too. Where to perform what calculations is as much a balancing act in games as anything else.


      • Originally posted by deanjo View Post
        Can you do it better and at equal or greater complexity in real time?

        Of course, the real kicker in the argument is that if Ageia had been purchased by AMD, would he then say that "PhysX was the greatest thing since sliced bread?"

        Politics are grand.