Legacy Documentation: Version 2018.2 (Go to current version)
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Rigidbody.OnCollisionEnter(Collision)

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Description

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. Notes: Collision events are only sent if one of the colliders also has a non-kinematic rigidbody attached. Collision events will be sent to disabled MonoBehaviours, to allow enabling Behaviours in response to collisions.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { AudioSource audioSource;

void Start() { audioSource = GetComponent<AudioSource>(); }

void OnCollisionEnter(Collision collision) { // Debug-draw all contact points and normals foreach (ContactPoint contact in collision.contacts) { Debug.DrawRay(contact.point, contact.normal, Color.white); }

// Play a sound if the colliding objects had a big impact. if (collision.relativeVelocity.magnitude > 2) audioSource.Play(); } }

Another example:

// A grenade
// instantiates a explosion prefab when hitting a surface
// then destroys itself
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { public Transform explosionPrefab; void OnCollisionEnter(Collision collision) { ContactPoint contact = collision.contacts[0];

// Rotate the object so that the y-axis faces along the normal of the surface Quaternion rot = Quaternion.FromToRotation(Vector3.up, contact.normal); Vector3 pos = contact.point; Instantiate(explosionPrefab, pos, rot); Destroy(gameObject); } }

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