The high performance open source Bullet Physics library now available within Unity. Wanting more flexibility than I could get using PhysX, I started this Unity port of the open source BulletSharp project. Bullet Physics is compiled as a native plugin and accessed from unity scripts using C# PInvoke wrappers.

* Simulate multiple physics worlds simultaneously
* Simulations independent of game loop
* Access to every byte of source code
* Softbodies, ropes, cables and cloth
* Featherstone inverse dynamics
* Two APIs:
. . . * Low level Bullet Physics API
. . . * Unity components similar to the PhysX components
* ZLib license (very permissive)

Currently supports:
* Windows
* OSX
* iOS
* Android

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