Bullet Physics is a professional open source collision detection, rigid body and soft body dynamics library written in portable C++. The library is primarily designed for use in games, visual effects and robotic simulation. The library is free for commercial use under the ZLib license and available on windows, mac and linux.

Main Features

Discrete and continuous collision detection including ray and convex sweep test. Collision shapes include concave and convex meshes and all basic primitives
Maximal coordinate 6-degree of freedom rigid bodies (btRigidBody) connected by constraints (btTypedConstraint) as well as generalized coordinate multi-bodies (btMultiBody) connected by mobilizers using the articulated body algorithm.
Fast and stable rigid body dynamics constraint solver, vehicle dynamics, character controller and slider, hinge, generic 6DOF and cone twist constraint for ragdolls
Soft Body dynamics for cloth, rope and deformable volumes with two-way interaction with rigid bodies, including constraint support
Open source C++ code under Zlib license and free for any commercial use on all platforms including PLAYSTATION 3, XBox 360, Wii, PC, Linux, Mac OSX, Android and iPhone
Maya Dynamica plugin, Blender integration, native binary .bullet serialization and examples how to import URDF, Wavefront .obj and Quake .bsp files.
Many examples showing how to use the SDK. All examples are easy to browse in the OpenGL 3 example browser. Each example can also be compiled without graphics.

Getting Started

Based on your goals with bullet, check out one of the corresponding sections