private void OnTriggerStay(Collider col)
 {
     if (col.gameObject.CompareTag("Throwable"))
     {
         if (!ballHandler.IsInPlayArea())
         {
             ballHandler.ReStart();
             alert.gameObject.SetActive(true);
             Invoke("RemoveAlert", 5.0f);
         }
         if (device.GetPressUp(SteamVR_Controller.ButtonMask.Trigger))
         {
             if (ballHandler.IsInPlayArea())
             {
                 ThrowObject(col);
             }
         }
         else if (device.GetPressDown(SteamVR_Controller.ButtonMask.Trigger))
         {
             GrabObject(col);
         }
     }
     if (col.gameObject.CompareTag("Structure"))
     {
         if (device.GetPressUp(SteamVR_Controller.ButtonMask.Trigger))
         {
             PutObject(col);
         }
         else if (device.GetPressDown(SteamVR_Controller.ButtonMask.Trigger))
         {
             GrabObject(col);
         }
     }
 }