Box2D is a 2D physics engine for games. Collision: * Continuous collision detection * Contact callbacks: begin, end, pre-solve, post-solve * Convex polygons and circles * Multiple shapes per body * One-shot contact manifolds * Dynamic tree broadphase * Efficient pair management * Fast broadphase AABB queries * Collision groups and categories Physics: * Continuous physics with time of impact 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, mouse joint, other joint types * Joint limits, motors, and friction * Momentum decoupled position correction
