Adds Missing Ceiling Overlay + Fixes Space on Roof

On Multi-Z compatible maps, if a tile is missing a ceiling (IE there is an open space above it), it will display an overlay to show this. This makes it easier to know where the hole in the ceiling is without having to go to the ceiling. Overlay sprite by Mechoid.
Also fixes space tiles appearing when meteors/explosions/other fun things occur on the Southern Cross map instead of open space.

code/game/area/Space Station 13 areas.dm

@@ -1645,7 +1645,6 @@ area/space/atmosalert()
 	requires_power = 1
 	always_unpowered = 1
 	dynamic_lighting = 0
-	base_turf = /turf/space
 
 	auxport
 		name = "\improper Fore Port Solar Array"

code/game/objects/items/weapons/RCD.dm

@@ -122,10 +122,7 @@
 		build_delay = deconstruct ? 50 : 20
 		build_cost =  deconstruct ? 10 : 3
 		build_type =  deconstruct ? "floor" : "wall"
-		if(F.check_destroy_override(F))
-			build_turf =  deconstruct ? destroy_floor_override_path : /turf/simulated/wall
-		else
-			build_turf =  deconstruct ? /turf/space : /turf/simulated/wall
+		build_turf =  deconstruct ? get_base_turf_by_area(F) : /turf/simulated/wall
 
 	if(!build_type)
 		working = 0

code/game/turfs/simulated.dm

@@ -62,16 +62,6 @@
 /turf/simulated/proc/initialize()
 	return
 
-/turf/simulated/proc/check_destroy_override()
-	if(destroy_floor_override) //Don't bother doing the additional checks if we don't have to.
-		var/area/my_area = get_area(src)
-//		my_area = my_area.master
-		if(is_type_in_list(my_area, destroy_floor_override_ignore_areas))
-			return 0
-		if(z in destroy_floor_override_z_levels)
-			return 1
-	return 0
-
 /turf/simulated/proc/AddTracks(var/typepath,var/bloodDNA,var/comingdir,var/goingdir,var/bloodcolor="#A10808")
 	var/obj/effect/decal/cleanable/blood/tracks/tracks = locate(typepath) in src
 	if(!tracks)

code/game/turfs/simulated/floor_icon.dm

@@ -84,6 +84,11 @@ var/list/flooring_cache = list()
 				continue
 			F.update_icon()
 
+	// Show 'ceilingless' overlay.
+	var/turf/above = GetAbove(src)
+	if(above && isopenspace(above) && !istype(src, /turf/simulated/floor/outdoors)) // This won't apply to outdoor turfs since its assumed they don't have a ceiling anyways.
+		overlays |= image(icon = 'icons/turf/open_space.dmi', icon_state = "no_ceiling", layer = TURF_LAYER + 0.02)
+
 /turf/simulated/floor/proc/get_flooring_overlay(var/cache_key, var/icon_base, var/icon_dir = 0)
 	if(!flooring_cache[cache_key])
 		var/image/I = image(icon = flooring.icon, icon_state = icon_base, dir = icon_dir)

code/game/turfs/simulated/walls.dm

@@ -211,10 +211,7 @@
 /turf/simulated/wall/ex_act(severity)
 	switch(severity)
 		if(1.0)
-			if(check_destroy_override())
-				src.ChangeTurf(destroy_floor_override_path)
-			else
-				src.ChangeTurf(/turf/space)
+			src.ChangeTurf(get_base_turf_by_area(src))
 		if(2.0)
 			if(prob(75))
 				take_damage(rand(150, 250))

code/game/turfs/turf_changing.dm

@@ -12,9 +12,14 @@
 // Called after turf replaces old one
 /turf/proc/post_change()
 	levelupdate()
-	var/turf/simulated/open/T = GetAbove(src)
-	if(istype(T))
-		T.update_icon()
+
+	var/turf/simulated/open/above = GetAbove(src)
+	if(istype(above))
+		above.update_icon()
+
+	var/turf/simulated/below = GetBelow(src)
+	if(istype(below))
+		below.update_icon() // To add or remove the 'ceiling-less' overlay.
 
 //Creates a new turf
 /turf/proc/ChangeTurf(var/turf/N, var/tell_universe=1, var/force_lighting_update = 0)

code/global.dm

@@ -38,17 +38,6 @@ var/changelog_hash		= ""
 var/game_year			= (text2num(time2text(world.realtime, "YYYY")) + 544)
 var/round_progressing = 1
 
-	//On some maps, it does not make sense for space turf to appear when something blows up (e.g. on an asteroid colony, or planetside)
-	//The turf listed here is what is created after ex_act() and other tile-destroying procs are called on a turf that
-	//is not already in a blacklisted area.
-	//Set to 1 to enable it.
-var/destroy_floor_override = 1
-	//Below is the path of turf used in place of space tiles.
-var/destroy_floor_override_path = /turf/simulated/mineral/floor
-	//A list of z-levels to apply the override to.  This is so z-levels like tcomms work as they did before.
-var/list/destroy_floor_override_z_levels = list(1,4,5)
-	//Some areas you may want to not turn into the override path you made above, like space or the solars.
-var/list/destroy_floor_override_ignore_areas = list(/area/space,/area/solar,/area/shuttle)
 var/master_mode       = "extended" // "extended"
 var/secret_force_mode = "secret"   // if this is anything but "secret", the secret rotation will forceably choose this mode.
 

code/modules/multiz/turf.dm

@@ -52,6 +52,7 @@
 	below = GetBelow(src)
 	turf_changed_event.register(below, src, /turf/simulated/open/update_icon)
 	levelupdate()
+	below.update_icon() // So the 'ceiling-less' overlay gets added.
 	for(var/atom/movable/A in src)
 		A.fall()
 	OS_controller.add_turf(src, 1)

maps/northern_star/northern_star.dm

@@ -7,6 +7,7 @@
 	#include "polaris-5.dmm"
 
 	#include "northern_star_defines.dm"
+	#include "northern_star_areas.dm"
 	#include "northern_star_shuttles.dm"
 
 	#define USING_MAP_DATUM /datum/map/northern_star

maps/northern_star/northern_star_areas.dm

@@ -0,0 +1,5 @@
+// Eventually we should move all the Northern Star-centric areas here so future maps can have a less polluted area list but that involves a lot of work and headaches.
+
+// Solars are 'sticking out' from the rock and so shouldn't have rock underneath them.
+/area/solar
+	base_turf = /turf/space