1. Collision Detection, Prefabs
Unity Notes
Collision Detection, Prefabs

2. Colliders Unity components that handle collisions
Basic shapes: box, sphere, capsule
Custom shape: mesh

3. Rigidbody
Gives an object mass and puts it under control of Unity’s physics engine
At least 1 colliding body must have a rigidbody component to get collision events
Can turn off gravity
Can be “kinematic” or unaffected by physics

4. Mouse Events To register mouse events, an object must have a collider
Implement OnMouseEnter, OnMouseOver, OnMouseDown, OnMouseUp…
Mouse position (screen coordinates) given by Input.MousePosition

5. Collisions
Entities with colliders (at least one rigidbody) get collision events
Implement the OnCollisionEnter(Collision c) method
The collision object has lots of information – the one you probably want is c.gameObject (the object you collided with)

6. Prefabs Prefabs are objects that may not be in the scene yet
Can be instantiated to add to the scene
Similar to cloning an object