Though not a selectable or configurable setting, The Witcher 3: Wild Hunt also features NVIDIA PhysX, which adds realistic cloth and destruction effects throughout the game. Powered by the CPU and available on all platforms, these effects make the world feel more alive and dynamic, with cloth blowing the in the wind and objects exploding realistically. On PC, these effects run at a higher detail level and with additional particles that further increase their fidelity and realism.
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That's a bummer, but quite a good thing for those who don't have the green hardware inside their personal computers
I was digging further and I just recently discovered that the hair simulation is not Physx but actually runs in direct compute. So my question is does the witcher have hardware physx and will I benefit from a dedicated physx card? Personally I don't think so any more but according to these tables avaialble at
http://www.geforce.com/whats-new/articles/the-witcher-3-wild-hunt-is-your-system-ready I will be able to play the game just fine on 1080p/ultra with all the lovely physx effects on with a stable 60 or more framerate.
Also The hair and fur physics uses DirectCompute, but everything else will use PhysX for the underlying solver (including Apex), and PhysX is scalable.. I would expect the Witcher 3 to have fog, smoke, water simulation, turbulence and other advanced particle effects as well which will benefit from, or be exclusive to hardware acceleration.
Cloth and destruction will use Apex, which is just an artist tool to speed up development but still relies on PhysX to do the processing... Apex can be designated to run on either the CPU or GPU (so the consoles can use Apex), the difference is of course the amount of computational power. On the CPU, the cloth simulation will be good, but not as awesome as on the GPU which can afford a lot more processing power for simulation.. So basically, hardware acceleration should give you better cloth simulation, and likely MORE as well. There can be multiple instances of high level cloth simulation on screen at the same time, such as environmental cloth effects that would be absent on CPU only Apex..
Same for the destruction effects. On CPU, the destruction effects will be good, but with GPU acceleration they will be greater and use more particles and debris..
Iam really looking forward on how nvidia and cd projekt red implemented these PC only graphical features and effects