Check when RaycastAll leaves an object

Ello peeps,

I'm making a MOBA game and I'm using a field of cubes that serves as my fog of war. I'm using a normal raycast to see if there is an obstacle that makes the viewing range smaller, after which I use a RaycastAll to find all the cubes that the raycast passes. However, the cubes only dissapear for a milisecond and then come back, while I need them to come back when the raycast doesn't pass through them anymore. Here's my script so far:

 using UnityEngine;
 using System.Collections;
 
 [AddComponentMenu("Fog Of War/Fog Of War")]
 
 public class FogOfWar : MonoBehaviour {
     public string fogCubeTag;
     public LayerMask ignoredLayers;
     public LayerMask ignoredLayers2;
 
     void Update() {
         RaycastHit hit;
         Vector3 dir = transform.TransformDirection(Vector3.forward);
 
         if(Physics.Raycast(transform.position, dir, out hit, 10, ignoredLayers)) {
             float dist = Vector3.Distance(transform.position, hit.point);
 
             RaycastHit[] hits;
             hits = Physics.RaycastAll(transform.position, dir, dist, ignoredLayers2);
             int i = 0;
             while(i < hits.Length) {
                 RaycastHit hit1 = hits[i];
                 GameObject cube = hit1.transform.gameObject;
                 if(cube) {
                     cube.GetComponent<MeshRenderer>().enabled = false;
                 }
                 i++;
             }
         }
     }
 }

Thanks in advance.