问题
When I looked at using PhysX, one had to install a runtime a bit like installing .NET. However I note Unity3D employs PhysX and Unity3D plugin installation is fairly simple and doesn't appear to add 3rd-party components. How is this possible?
回答1:
As a partner, they presumably would have access to special builds or even source code for PhysX, allowing Unity to link in or bundle with PhysX directly. Just because a core technology is distributed one way (say the end-user run-time or nVidia drivers), doesn't mean that that's the only way.
Also keep in mind, PhysX doesn't require hardware acceleration and can act as a software physics engine by itself.
回答2:
As of phyx 3.x it's not necessary to install drivers,
http://physxinfo.com/wiki/PhysX_SDK_3.x
I think they might have restructured how they look for dlls to not require that they get dropped into the windows directory.
来源：https://stackoverflow.com/questions/7097747/how-does-unity3d-use-physx-without-requiring-the-physx-runtime