Unity physics

1. Physics overview

   Built-in 3D physics (PhysX) and 2D physics (Box2D).

2. Rigidbody

   Mass, drag, forces, kinematic bodies and interpolation.

3. Colliders

   Primitive and mesh colliders, trigger vs collision.

4. Collision events

   OnCollisionEnter, OnTriggerEnter and collision matrix.

5. Joints

   Hinge, spring and configurable joints.

6. Character controllers

   CharacterController and Move.

7. Physics 2D

   Rigidbody2D and Collider2D.

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