Chipmunk Game Dynamics (open source)

[Tami]

Chipmunk is a 2D rigid body physics library distributed under the MIT license. Though not yet complete, it is intended to be fast, numerically stable, and easy to use.

Features:

* Designed for 2D video games.
* Circle, convex polygon, and line segment collision primitives.
* Multiple collision primitives can be attached to the same rigid body.
* Fast collision detection by using a spatial hash for the broad phase.
* Extremely fast impulse solving by utilizing Erin Catto’s contact persistence algorithm.
* Support for collision callbacks based on object types.
* Impulses applied to contact points can be retrieved after the impulse solver has finished.
* Several kinds of joints available.
* C99 implementation, no external dependencies.
* Ruby extension available.
* Simple, read the documentation.
* Unrestrictive MIT license.