All atoms changing opacity will recalculate visibility (#10352)

code/modules/mob/abstract/freelook/update_triggers.dm

@@ -1,20 +1,19 @@
 //UPDATE TRIGGERS, when the chunk (and the surrounding chunks) should update.
 
-// TURFS
-
 /proc/updateVisibility(atom/A, var/opacity_check = TRUE)
 	if(SSticker)
 		for(var/datum/visualnet/VN in visual_nets)
 			VN.update_visibility(A, opacity_check)
 
-/turf/drain_power()
-	return -1
-
 /atom/Destroy()
 	if(opacity)
 		updateVisibility(src)
 	. = ..()
 
+/atom/set_opacity()
+	. = ..()
+	if(.)
+		updateVisibility(src, FALSE)
 
 /atom/movable/Move()
 	. = ..()
@@ -26,16 +25,6 @@
 	if(opacity && .)
 		updateVisibility(src)
 
-// DOORS
-
-// Simply updates the visibility of the area when it opens/closes/destroyed.
-/obj/machinery/door/update_nearby_tiles(need_rebuild)
-	. = ..(need_rebuild)
-	// Glass door glass = 1
-	// don't check then?
-	if(!glass)
-		updateVisibility(src, FALSE)
-
 /turf/ChangeTurf()
 	. = ..()
 	if(.)