MonoBehaviour.OnCollisionStay(Collision)

Description

OnCollisionStay is called once per frame for every collider/rigidbody that is touching rigidbody/collider.

In contrast to OnTriggerStay, OnCollisionStay 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. Collision stay events are not sent for sleeping Rigidbodies.

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

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void OnCollisionStay(Collision collisionInfo) {
        foreach (ContactPoint contact in collisionInfo.contacts) {
            Debug.DrawRay(contact.point, contact.normal, Color.white);
        }
    }
}

OnCollisionStay can be a co-routine, simply use the yield statement in the function.