MonoBehaviour.OnCollisionEnter(Collision)

Parameters

Description

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

OnCollisionEnter receives an instance of the Collision class as the collision paramter. This parameter contains information about the collision such as contact points and impact velocity. If you don't use this collision data in your OnCollisionEnter callback, leave out the collision parameter from the method declaration to avoid unneccessary calculations.

Note: 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.

OnCollisionEnter can be a coroutine

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    AudioSource audioSource;

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

    void OnCollisionEnter(Collision collision)
    {
        foreach (ContactPoint contact in collision.contacts)
        {
            Debug.DrawRay(contact.point, contact.normal, Color.white);
        }

        if (collision.relativeVelocity.magnitude > 2)
            audioSource.Play();
    }
}