title: Making an object detect that raycast not hitting it anymore
body: <p>I use SendMessage to inform the Object that is was hit by a Raycast:</p>
  
  <pre><code>     using UnityEngine;
  
   public class Raycaster : MonoBehaviour {
       void Update() {
           RaycastHit hit;
           if (Physics.Raycast(transform.position, transform.forward, out hit))
            if(hit.transform.tag == "MyGameObject"){
              hit.transform.SendMessage ("HitByRay");
              }  
       }
   }
  </code></pre>
  
  <p>And object have a script like this:</p>
  
  <pre><code>using UnityEngine;
  
   public class ObjectHit : MonoBehaviour {
       void HitByRay () {
           Debug.Log ("I was hit by a Ray");
       }
   }
  </code></pre>
  
  <p>And that print message "I was hit by Ray" in every frame.
  Now i need to inform that Game Object that raycast not hitting it anymore.</p>