Bullet is an open source physics engine, hosted at Sourceforge. It uses the ZLib license, and is therefore free for commercial use, including Playstation 3. Its author Erwin Coumans previously worked for the Havok project.

Features:

• collision shapes include: Sphere, box, cylinder, cone, convex hull, and triangle mesh
• implements GJK convex collision detection
• swept collision test
• continuous Collision Detection
• constraints
• COLLADA 1.4 Physics import
• modular approach supports home-brewed physics software

Bullet provides rigid body physics for the Blender 3-D modeling, rendering, and animation package.

The Bullet website also hosts a Physics Forum for general discussion around Physics Simulation for Games and Animation.

Game engines