Rigidbody.OnCollisionEnter Manual     Reference     Scripting  
Scripting > Runtime Classes > Rigidbody

function OnCollisionEnter (collisionInfo : Collision) : void


OnCollisionEnter is called when this collider/rigidbody has begun touching another rigidbody/collider.

In contrast to OnTriggerEnter, OnCollisionEnter is passed the Collision class and not a Collider. The Collision class contains information about contact points, impact velocity etc. If you don't use collisionInfo in the function, leave out the collisionInfo parameter as this avoids unneccessary calculations. Note that collision events are only sent if one of the colliders also has a non-kinematic rigidbody attached.

function OnCollisionEnter(collision : Collision) {
// Debug-draw all contact points and normals
for (var contact : ContactPoint in collision.contacts) {
Debug.DrawRay(contact.point, contact.normal, Color.white);

// Play a sound if the coliding objects had a big impact.
if (collision.relativeVelocity.magnitude > 2)

// A grenade
// - instantiates a explosion prefab when hitting a surface
// - then destroys itself
var explosionPrefab : Transform;
function OnCollisionEnter(collision : Collision) {
// Rotate the object so that the y-axis faces along the normal of the surface
var contact = collision.contacts[0];
var rot = Quaternion.FromToRotation(Vector3.up, contact.normal);
var pos = contact.point;
Instantiate(explosionPrefab, pos, rot);
// Destroy the projectile
Destroy (gameObject);