GameObject collisions cheatsheet

Collider

`OnCollisionEnter2D`	Called when this collider/rigidbody has begun touching another rigidbody/collider
`OnCollisionExit2D`	Called when this collider/rigidbody has stopped touching another rigidbody/collider.
`OnTriggerEnter2D`	Called when this Collider other enters a trigger Collider.
`OnTriggerExit2D`	Called when this Collider other has stopped touching a trigger collider.
`isTrigger`	Triggers collision without physics
`Physics.Raycast`	Checks if there are colliders in a line

RigidBody

`isKinematic`	Controls whether physics affects the rigidbody.
`useGravity`	Controls whether gravity affects this rigidbody.
`addForce`	Applies a force of a vector to the rigidbody
`AddTorque`	Adds torque to the rigidbody

Usage

/* Both objects have to have a Collider and one object has to have a Rigidbody for these Events to work */
private void OnCollisionEnter(Collision hit) {    
  Debug.Log(gameObject.name + " hits " + hit.gameObject.name); 
}
private void OnCollisionStay(Collision hit) {  
  Debug.Log(gameObject.name + " is hitting " + hit.gameObject.name); 
}
private void OnCollisionExit(Collision hit) { 
  Debug.Log(gameObject.name + " stopped hitting " + hit.gameObject.name); 
}

// Trigger must be checked on one of the Colliders
private void OnTriggerEnter(Collider hit) {    
  Debug.Log(gameObject.name + " just hit " + hit.name); 
}
private void OnTriggerStay(Collider hit) { 
  Debug.Log(gameObject.name + " is hitting " + hit.name); 
}
private void OnTriggerExit(Collider hit) { 
  Debug.Log(gameObject.name + " stopped hitting " + hit.name); 
}
 
// For 2D Colliders
private void OnCollisionEnter2D(Collision2D hit) { }
private void OnCollisionStay2D(Collision2D hit) { }
private void OnCollisionExit2D(Collision2D hit) { }
private void OnTriggerEnter2D(Collider2D hit) { }
private void OnTriggerStay2D(Collider2D hit) { }
private void OnTriggerExit2D(Collider2D hit) { }

// Ray casting to detect the collision
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
RaycastHit hit;
if (Physics.Raycast(ray, out hit, 100)){
  Debug.DrawLine(ray.origin, hit.point);
  Debug.Log("Hit: " + hit.collider.name);
}