Box2DX is a C# port of Box2D - Erin Catto's 2D Physics Engine. You can find original C++ version on www.box2d.org

Collision: * Continuous collision detection. * Contact callbacks: add, persist, remove. * Convex polyons and circles. * Multiple shapes per body. * One-shot contact manifolds. * Incremental sweep-and-prune broadphase. * Efficient pair management. * Fast broadphase AABB queries. * Collision groups and categories.

Physics: * Continuous physics with time of impact island solver. * Persistent body-joint-contact graph. * Island solution and sleep management. * Contact, friction, and restitution. * Stable stacking with a linear-time solver. * Revolute, prismatic, distance, pulley, gear, and mouse joints. * Joint limits, motors, and friction. * Momentum decoupled position correction. * Fairly accurate reaction forces/impulses.

System: * Centralized tuning parameters. * Pure .NET 2.0 library.

Documentation:

Testbed: * OpenGL with Tao.Freeglut * Graphical user interface * Easily switch between tests using GUI * Test framework for easily adding new tests * Mouse picking and the bomb! * VCS9 project files

The Library is free for commercial use and open source under the ZLib License.