Collider and rigidbody

For a basic gameplay, I wanted to destroy the asteroid when the laser beam hits it. Meaning, the collision between asteroid and laser bullet destroys asteroid. At the same time, laser bullet that collided should also be destroyed. 

In Unity, OnTriggerEnter method is called when two GameObjects collide. During this event:

• Both the game objects should have Collider component, and

• One of the game Objects must have Collider.isTarget enabled, and contain a Rigidbody

COLLIDER

• To add a collider in asteroids, the prefabs were opened and Box Collider were added. 

• Box Collider were sized such that the asteroid is covered in all sides

• In laser beams, a capsule collider was added.

RIGIDBODY

• Rigidbody adds a physics simulation in an object.

• In our game "Use Gravity" should not be checked. This will make the object fall in y-direction due to gravity.