Flattens The Floor Plane (Camera Update Too) (tgstation#84350)

## About The Pull Request

Ok so like, side map right? It makes things higher up in the world
render above things lower down in the world.

Most of the time this is what we want, but it is NOT what we want for
floors.
Floors are allowed to be larger then 32x32, and if they are we want them
to render based off JUST their layer.
If we don't allow this grass turfs and others get cut off on their
bottom edge, which looks WEIRD.

In order to make this happen, we can add TOPDOWN_LAYER to every layer on
the floor plane and disable sidemap.

I've added documentation for this to VISUALS.md, and have also
implemented unit test errors to prevent mixing TOPDOWN layers with non
topdown planes (or vis versa).
This new test adds ~1 second to tests, which is I think a perfectly
scrumpulent number.

EDIT:

I nerd sniped myself and implemented sidemap layering and lighting for
cameras (also larger then 32x32 icon support for getflat)
The lighting isn't perfect, we don't handle things displaying in the
void all that well (I am convinced getflat blending is broken but I have
no debugger so I can't fix it properly), but it'll do.

This came up cause I had to fix another layering issue in cameras and
thought I might as well go all in.

![image](https://github.com/tgstation/tgstation/assets/58055496/601b422c-f6aa-42ba-bcd9-b1faebe236e3)


## Why It's Good For The Game

Old:

![image](https://github.com/tgstation/tgstation/assets/58055496/d4102386-420d-4346-b05c-b819e62d98d0)

New:

![image](https://github.com/tgstation/tgstation/assets/58055496/1f5e303e-adee-427d-8fe3-76c8f2dbe098)


## Changelog
:cl:
fix: Grass turfs will render properly now. Reworked how floors render,
please report any bugs!
fix: Cameras now properly capture lighting
fix: The layering seen in photos should better match the actual game
/:cl:

.github/guides/VISUALS.md

@@ -406,6 +406,9 @@ There are a few snowflake layers that can be used to accomplish niche goals, alo
 
 Floating layers will float "up" the chain of things they're being drawn onto, until they find a real layer. They'll then offset off of that.
 
+Adding `TOPDOWN_LAYER` (actual value `10000`) to another layer forces the appearance into topdown rendering, locally disabling [side map](#side_map-check-the-main-page-too).
+We can think of this as applying to planes, since we don't want it interlaying with other non topdown objects.
+
 This allows us to keep relative layer differences while not needing to make all sources static. Often very useful.
 
 ## Planes

code/__DEFINES/layers.dm

@@ -122,23 +122,37 @@
 // PLANE_SPACE layer(s)
 #define SPACE_LAYER 1.8
 
-//#define TURF_LAYER 2 //For easy recordkeeping; this is a byond define. Most floors (FLOOR_PLANE) and walls (WALL_PLANE) use this.
+// placed here for documentation. Byond's default turf layer
+// We do not use it, as different turfs render on different planes
+// #define TURF_LAYER 2
+#define TURF_LAYER 2 #error TURF_LAYER is no longer supported, please be more specific
+
+// FLOOR_PLANE layer(s)
+// We need to force this plane to render as if we were not using sidemap
+// this allows larger then bound floors to layer as we'd expect
+// ANYTHING on the floor plane needs TOPDOWN_LAYER, and nothing that isn't on the floor plane can have it
 
 //FLOOR_PLANE layers
-#define TURF_PLATING_DECAL_LAYER 2.001
-#define TURF_DECAL_LAYER 2.009 //Makes turf decals appear in DM how they will look inworld.
-#define CULT_OVERLAY_LAYER 2.01
-#define MID_TURF_LAYER 2.02
-#define HIGH_TURF_LAYER 2.03
-#define LATTICE_LAYER 2.04
-#define DISPOSAL_PIPE_LAYER 2.042
-#define WIRE_LAYER 2.044
-#define GLASS_FLOOR_LAYER 2.046
-#define TRAM_RAIL_LAYER 2.047
-#define ABOVE_OPEN_TURF_LAYER 2.049
+// NOTICE: we break from the pattern of increasing in steps of like 0.01 here
+// Because TOPDOWN_LAYER is 10000 and that's enough to floating point our modifications away
+#define LOW_FLOOR_LAYER (1 + TOPDOWN_LAYER)
+#define TURF_PLATING_DECAL_LAYER (2 + TOPDOWN_LAYER)
+#define TURF_DECAL_LAYER (3 + TOPDOWN_LAYER) //Makes turf decals appear in DM how they will look inworld.
+#define CULT_OVERLAY_LAYER (4 + TOPDOWN_LAYER)
+#define MID_TURF_LAYER (5 + TOPDOWN_LAYER)
+#define HIGH_TURF_LAYER (6 + TOPDOWN_LAYER)
+#define LATTICE_LAYER (7 + TOPDOWN_LAYER)
+#define DISPOSAL_PIPE_LAYER (8 + TOPDOWN_LAYER)
+#define WIRE_LAYER (9 + TOPDOWN_LAYER)
+#define GLASS_FLOOR_LAYER (10 + TOPDOWN_LAYER)
+#define TRAM_RAIL_LAYER (11 + TOPDOWN_LAYER)
+///catwalk overlay of /turf/open/floor/plating/catwalk_floor
+#define CATWALK_LAYER (12 + TOPDOWN_LAYER)
+#define ABOVE_OPEN_TURF_LAYER (13 + TOPDOWN_LAYER)
 
 //WALL_PLANE layers
-#define CLOSED_TURF_LAYER 2.05
+#define BELOW_CLOSED_TURF_LAYER 2.053
+#define CLOSED_TURF_LAYER 2.058
 
 // GAME_PLANE layers
 #define BULLET_HOLE_LAYER 2.06
@@ -153,8 +167,6 @@
 #define PLUMBING_PIPE_VISIBILE_LAYER 2.495//layer = initial(layer) + ducting_layer / 3333 in atmospherics/handle_layer() to determine order of duct overlap
 #define BOT_PATH_LAYER 2.497
 #define LOW_OBJ_LAYER 2.5
-///catwalk overlay of /turf/open/floor/plating/catwalk_floor
-#define CATWALK_LAYER 2.51
 #define LOW_SIGIL_LAYER 2.52
 #define SIGIL_LAYER 2.53
 #define HIGH_PIPE_LAYER 2.54

code/__HELPERS/_planes.dm

@@ -86,3 +86,19 @@
 // This is solvable with lowspec preferences, which would not be hard to implement
 // Player popups will now render their effects, like overlay lights. this is fixable, but I've not gotten to it
 // I think overlay lights can render on the wrong z layer. s fucked
+
+/// Whitelist of planes allowed to use TOPDOWN_LAYER
+GLOBAL_LIST_INIT(topdown_planes, list(
+		"[FLOOR_PLANE]" = TRUE,
+	))
+
+/// Checks if a passed in MA or atom is allowed to have its current plane/layer matchup
+/proc/check_topdown_validity(mutable_appearance/thing_to_check)
+	if(istype(thing_to_check, /atom/movable/screen/plane_master))
+		return
+	var/topdown_plane = GLOB.topdown_planes["[PLANE_TO_TRUE(thing_to_check.plane)]"]
+	if(topdown_plane)
+		if(thing_to_check.layer - TOPDOWN_LAYER < 0 || thing_to_check.layer >= BACKGROUND_LAYER)
+			stack_trace("[thing_to_check] ([thing_to_check.type]) was expected to have a TOPDOWN_LAYER layer due to its plane, but it DID NOT! layer: ([thing_to_check.layer]) plane: ([thing_to_check.plane])")
+	else if(thing_to_check.layer - TOPDOWN_LAYER >= 0 && thing_to_check.layer < BACKGROUND_LAYER)
+		stack_trace("[thing_to_check] ([thing_to_check.type] is NOT ALLOWED to have a TOPDOWN_LAYER layer due to its plane, but it did! layer: ([thing_to_check.layer]) plane: ([thing_to_check.plane])")

code/__HELPERS/icon_smoothing.dm

@@ -493,7 +493,7 @@ xxx xxx xxx
 			var/junction_dir = reverse_ndir(smoothing_junction)
 			var/turned_adjacency = REVERSE_DIR(junction_dir)
 			var/turf/neighbor_turf = get_step(src, turned_adjacency & (NORTH|SOUTH))
-			var/mutable_appearance/underlay_appearance = mutable_appearance(layer = TURF_LAYER, offset_spokesman = src, plane = FLOOR_PLANE)
+			var/mutable_appearance/underlay_appearance = mutable_appearance(layer = LOW_FLOOR_LAYER, offset_spokesman = src, plane = FLOOR_PLANE)
 			if(!neighbor_turf.get_smooth_underlay_icon(underlay_appearance, src, turned_adjacency))
 				neighbor_turf = get_step(src, turned_adjacency & (EAST|WEST))
 

code/__HELPERS/icons.dm

@@ -420,6 +420,10 @@ world
 				} \
 				current_layer = base_layer + appearance.layer + current_layer / 1000; \
 			} \
+			/* If we are using topdown rendering, chop that part off so things layer together as expected */ \
+			if((current_layer >= TOPDOWN_LAYER && current_layer < EFFECTS_LAYER) || current_layer > TOPDOWN_LAYER + EFFECTS_LAYER) { \
+				current_layer -= TOPDOWN_LAYER; \
+			} \
 			for (var/index_to_compare_to in 1 to layers.len) { \
 				var/compare_to = layers[index_to_compare_to]; \
 				if (current_layer < layers[compare_to]) { \
@@ -431,9 +435,10 @@ world
 		}
 
 	var/static/icon/flat_template = icon('icons/blanks/32x32.dmi', "nothing")
+	var/icon/flat = icon(flat_template)
 
 	if(!appearance || appearance.alpha <= 0)
-		return icon(flat_template)
+		return flat
 
 	if(start)
 		if(!defdir)
@@ -474,10 +479,15 @@ world
 	if(!base_icon_dir)
 		base_icon_dir = curdir
 
+	// Expand our canvas to fit if we're too big
+	if(render_icon)
+		var/icon/active_icon = icon(curicon)
+		if(active_icon.Width() != 32 || active_icon.Height() != 32)
+			flat.Scale(active_icon.Width(), active_icon.Height())
+
 	var/curblend = appearance.blend_mode || defblend
 
 	if(appearance.overlays.len || appearance.underlays.len)
-		var/icon/flat = icon(flat_template)
 		// Layers will be a sorted list of icons/overlays, based on the order in which they are displayed
 		var/list/layers = list()
 		var/image/copy

code/_onclick/hud/picture_in_picture.dm

@@ -1,6 +1,7 @@
 /atom/movable/screen/movable/pic_in_pic
 	name = "Picture-in-picture"
 	screen_loc = "CENTER"
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE
 	var/atom/center
 	var/width = 0

code/datums/elements/turf_transparency.dm

@@ -219,10 +219,10 @@ GLOBAL_LIST_EMPTY(pillars_by_z)
 	// it will make them look significantly nicer, and should let you tie into their logic more easily
 	// Just please don't break behavior yeah? thanks, I love you <3
 	if(isclosedturf(our_turf)) //Show girders below closed turfs
-		var/mutable_appearance/girder_underlay = mutable_appearance('icons/obj/structures.dmi', "girder", layer = TURF_LAYER-0.01)
+		var/mutable_appearance/girder_underlay = mutable_appearance('icons/obj/structures.dmi', "girder", layer = BELOW_CLOSED_TURF_LAYER)
 		girder_underlay.appearance_flags = RESET_ALPHA | RESET_COLOR
 		our_turf.underlays += girder_underlay
-		var/mutable_appearance/plating_underlay = mutable_appearance('icons/turf/floors.dmi', "plating", layer = TURF_LAYER-0.02)
+		var/mutable_appearance/plating_underlay = mutable_appearance('icons/turf/floors.dmi', "plating", layer = LOW_FLOOR_LAYER, offset_spokesman = our_turf, plane = FLOOR_PLANE)
 		plating_underlay.appearance_flags = RESET_ALPHA | RESET_COLOR
 		our_turf.underlays += plating_underlay
 	return TRUE
@@ -240,10 +240,10 @@ GLOBAL_LIST_EMPTY(pillars_by_z)
 		our_turf.underlays -= get_baseturf_underlay(our_turf)
 
 	if(isclosedturf(our_turf)) //Show girders below closed turfs
-		var/mutable_appearance/girder_underlay = mutable_appearance('icons/obj/structures.dmi', "girder", layer = TURF_LAYER-0.01)
+		var/mutable_appearance/girder_underlay = mutable_appearance('icons/obj/structures.dmi', "girder", layer = BELOW_CLOSED_TURF_LAYER)
 		girder_underlay.appearance_flags = RESET_ALPHA | RESET_COLOR
 		our_turf.underlays -= girder_underlay
-		var/mutable_appearance/plating_underlay = mutable_appearance('icons/turf/floors.dmi', "plating", layer = TURF_LAYER-0.02)
+		var/mutable_appearance/plating_underlay = mutable_appearance('icons/turf/floors.dmi', "plating", layer = LOW_FLOOR_LAYER, offset_spokesman = our_turf, plane = FLOOR_PLANE)
 		plating_underlay.appearance_flags = RESET_ALPHA | RESET_COLOR
 		our_turf.underlays -= plating_underlay
 
@@ -271,7 +271,7 @@ GLOBAL_LIST_EMPTY(pillars_by_z)
 		if(!ispath(path))
 			warning("Z-level [our_turf.z] has invalid baseturf '[SSmapping.level_trait(our_turf.z, ZTRAIT_BASETURF)]'")
 			path = /turf/open/space
-	var/mutable_appearance/underlay_appearance = mutable_appearance(initial(path.icon), initial(path.icon_state), layer = TURF_LAYER-0.02, offset_spokesman = our_turf, plane = PLANE_SPACE)
+	var/mutable_appearance/underlay_appearance = mutable_appearance(initial(path.icon), initial(path.icon_state), layer = SPACE_LAYER + 0.1, offset_spokesman = our_turf, plane = PLANE_SPACE)
 	underlay_appearance.appearance_flags = RESET_ALPHA | RESET_COLOR
 	return underlay_appearance
 

code/datums/elements/undertile.dm

@@ -44,6 +44,7 @@
 
 	if(underfloor_accessibility < UNDERFLOOR_INTERACTABLE)
 		SET_PLANE_IMPLICIT(source, FLOOR_PLANE) // We do this so that turfs that allow you to see what's underneath them don't have to be on the game plane (which causes ambient occlusion weirdness)
+		source.layer = ABOVE_OPEN_TURF_LAYER
 		ADD_TRAIT(source, TRAIT_UNDERFLOOR, REF(src))
 
 		if(tile_overlay)
@@ -61,6 +62,7 @@
 
 	else
 		SET_PLANE_IMPLICIT(source, initial(source.plane))
+		source.layer = initial(source.layer)
 		REMOVE_TRAIT(source, TRAIT_UNDERFLOOR, REF(src))
 
 		if(invisibility_trait)

code/datums/mutable_appearance.dm

@@ -45,4 +45,7 @@
 	else if(!isnull(offset_spokesman) && !isatom(offset_spokesman))
 		stack_trace("Why did you pass in offset_spokesman as [offset_spokesman]? We need an atom to properly offset planes")
 
+	if(PERFORM_ALL_TESTS(focus_only/topdown_filtering))
+		check_topdown_validity(appearance)
+
 	return appearance

code/datums/weather/weather.dm

@@ -56,7 +56,7 @@
 	/// The list of z-levels that this weather is actively affecting
 	var/impacted_z_levels
 
-	/// Since it's above everything else, this is the layer used by default. TURF_LAYER is below mobs and walls if you need to use that.
+	/// Since it's above everything else, this is the layer used by default.
 	var/overlay_layer = AREA_LAYER
 	/// Plane for the overlay
 	var/overlay_plane = AREA_PLANE

code/game/atom/_atom.dm

@@ -5,7 +5,7 @@
  * as much as possible to the components/elements system
  */
 /atom
-	layer = TURF_LAYER
+	layer = ABOVE_NORMAL_TURF_LAYER
 	plane = GAME_PLANE
 	appearance_flags = TILE_BOUND|LONG_GLIDE
 

code/game/machinery/ai_slipper.dm

@@ -4,7 +4,7 @@
 	icon = 'icons/obj/devices/tool.dmi'
 	icon_state = "ai-slipper0"
 	base_icon_state = "ai-slipper"
-	layer = PROJECTILE_HIT_THRESHHOLD_LAYER
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE
 	max_integrity = 200
 	armor_type = /datum/armor/machinery_ai_slipper

code/game/machinery/hologram.dm

@@ -39,9 +39,9 @@ Possible to do for anyone motivated enough:
 	icon = 'icons/obj/machines/floor.dmi'
 	icon_state = "holopad0"
 	base_icon_state = "holopad"
-	layer = LOW_OBJ_LAYER
 	/// The plane is set such that it shows up without being covered by pipes/wires in a map editor, we change this on initialize.
-	plane = GAME_PLANE
+	layer = MAP_SWITCH(ABOVE_OPEN_TURF_LAYER, LOW_OBJ_LAYER)
+	plane = MAP_SWITCH(FLOOR_PLANE, GAME_PLANE)
 	req_access = list(ACCESS_KEYCARD_AUTH) //Used to allow for forced connecting to other (not secure) holopads. Anyone can make a call, though.
 	max_integrity = 300
 	armor_type = /datum/armor/machinery_holopad
@@ -101,9 +101,6 @@ Possible to do for anyone motivated enough:
 
 /obj/machinery/holopad/Initialize(mapload)
 	. = ..()
-	/// We set the plane on mapload such that we can see the holopad render over atmospherics pipe and cabling in a map editor (without initialization), but so it gets that "inset" look in the floor in-game.
-	SET_PLANE_IMPLICIT(src, FLOOR_PLANE)
-	update_appearance()
 
 	var/static/list/hovering_mob_typechecks = list(
 		/mob/living/silicon = list(

code/game/machinery/igniter.dm

@@ -4,6 +4,7 @@
 	icon = 'icons/obj/machines/floor.dmi'
 	icon_state = "igniter0"
 	base_icon_state = "igniter"
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE
 	max_integrity = 300
 	armor_type = /datum/armor/machinery_igniter

code/game/machinery/launch_pad.dm

@@ -98,7 +98,7 @@
 /// Updates diagnostic huds
 /obj/machinery/launchpad/proc/update_hud()
 	var/image/holder = hud_list[DIAG_LAUNCHPAD_HUD]
-	var/mutable_appearance/target = mutable_appearance('icons/effects/effects.dmi', "launchpad_target", ABOVE_OPEN_TURF_LAYER, src, GAME_PLANE)
+	var/mutable_appearance/target = mutable_appearance('icons/effects/effects.dmi', "launchpad_target", ABOVE_NORMAL_TURF_LAYER, src, GAME_PLANE)
 	holder.appearance = target
 
 	update_indicator()

code/game/objects/effects/blessing.dm

@@ -12,7 +12,7 @@
 	for(var/obj/effect/blessing/B in loc)
 		if(B != src)
 			return INITIALIZE_HINT_QDEL
-		var/image/I = image(icon = 'icons/effects/effects.dmi', icon_state = "blessed", layer = ABOVE_OPEN_TURF_LAYER, loc = src)
+		var/image/I = image(icon = 'icons/effects/effects.dmi', icon_state = "blessed", layer = ABOVE_NORMAL_TURF_LAYER, loc = src)
 		I.alpha = 64
 		I.appearance_flags = RESET_ALPHA
 		add_alt_appearance(/datum/atom_hud/alternate_appearance/basic/blessed_aware, "blessing", I)

code/game/objects/effects/decals/cleanable.dm

@@ -1,5 +1,6 @@
 /obj/effect/decal/cleanable
 	gender = PLURAL
+	plane = GAME_PLANE
 	layer = FLOOR_CLEAN_LAYER
 	var/list/random_icon_states = null
 	///I'm sorry but cleanable/blood code is ass, and so is blood_DNA

code/game/objects/effects/decals/decal.dm

@@ -1,5 +1,6 @@
 /obj/effect/decal
 	name = "decal"
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE
 	anchored = TRUE
 	resistance_flags = FIRE_PROOF | UNACIDABLE | ACID_PROOF

code/game/objects/effects/temporary_visuals/cult.dm

@@ -49,6 +49,7 @@
 /obj/effect/temp_visual/cult/turf/floor
 	icon_state = "floorglow"
 	duration = 5
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE
 
 /obj/effect/temp_visual/cult/portal

code/game/objects/items/devices/flashlight.dm

@@ -928,6 +928,7 @@
 	light_range = 4
 	light_power = 2
 	alpha = 0
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE
 	anchored = TRUE
 	resistance_flags = INDESTRUCTIBLE | LAVA_PROOF | FIRE_PROOF | UNACIDABLE | ACID_PROOF

code/game/objects/items/puzzle_pieces.dm

@@ -558,6 +558,7 @@ MAPPING_DIRECTIONAL_HELPERS(/obj/machinery/puzzle/password/pin, 32)
 	desc = "A board filled with colored dots. What could this mean?"
 	icon = 'icons/obj/fluff/puzzle_small.dmi'
 	icon_state = "puzzle_dots"
+	layer = ABOVE_NORMAL_TURF_LAYER
 	plane = GAME_PLANE //visible over walls
 	resistance_flags = INDESTRUCTIBLE | FIRE_PROOF | UNACIDABLE | LAVA_PROOF
 	flags_1 = UNPAINTABLE_1

code/game/objects/structures/fake_stairs.dm

@@ -6,6 +6,7 @@
 	anchored = TRUE
 	move_resist = INFINITY
 
+	layer = ABOVE_OPEN_TURF_LAYER
 	plane = FLOOR_PLANE //one with the floor
 
 MAPPING_DIRECTIONAL_HELPERS(/obj/structure/fake_stairs, 0)

code/game/objects/structures/fluff.dm

@@ -87,7 +87,7 @@
 	icon = 'icons/obj/mining_zones/survival_pod.dmi'
 	icon_state = "fan_tiny"
 	plane = FLOOR_PLANE
-	layer = LOW_OBJ_LAYER
+	layer = ABOVE_OPEN_TURF_LAYER
 
 /**
  * A variety of statue in disrepair; parts are broken off and a gemstone is missing

code/game/turfs/closed/walls.dm

@@ -99,7 +99,7 @@
 	if(is_station_level(z))
 		GLOB.station_turfs += src
 	if(smoothing_flags & SMOOTH_DIAGONAL_CORNERS && fixed_underlay) //Set underlays for the diagonal walls.
-		var/mutable_appearance/underlay_appearance = mutable_appearance(layer = TURF_LAYER, offset_spokesman = src, plane = FLOOR_PLANE)
+		var/mutable_appearance/underlay_appearance = mutable_appearance(layer = LOW_FLOOR_LAYER, offset_spokesman = src, plane = FLOOR_PLANE)
 		if(fixed_underlay["space"])
 			generate_space_underlay(underlay_appearance, src)
 		else

code/game/turfs/open/_open.dm

@@ -1,4 +1,5 @@
 /turf/open
+	layer = LOW_FLOOR_LAYER
 	plane = FLOOR_PLANE
 	///negative for faster, positive for slower
 	var/slowdown = 0

code/game/turfs/open/floor/catwalk_plating.dm

@@ -19,14 +19,10 @@
 	rust_resistance = RUST_RESISTANCE_BASIC
 	var/covered = TRUE
 	var/catwalk_type = "maint"
-	var/static/list/catwalk_underlays = list()
 
 /turf/open/floor/catwalk_floor/Initialize(mapload)
 	. = ..()
-	if(!catwalk_underlays[catwalk_type])
-		var/mutable_appearance/plating_underlay = mutable_appearance(icon, "[catwalk_type]_below", TURF_LAYER)
-		catwalk_underlays[catwalk_type] = plating_underlay
-	underlays += catwalk_underlays[catwalk_type]
+	underlays += mutable_appearance(icon, "[catwalk_type]_below", LOW_FLOOR_LAYER, src, FLOOR_PLANE)
 	update_appearance()
 
 /turf/open/floor/catwalk_floor/examine(mob/user)
@@ -43,7 +39,7 @@
 	covered = !covered
 	if(!covered)
 		underfloor_accessibility = UNDERFLOOR_INTERACTABLE
-		layer = TURF_LAYER
+		layer = LOW_FLOOR_LAYER
 		icon_state = "[catwalk_type]_below"
 	else
 		underfloor_accessibility = UNDERFLOOR_VISIBLE

code/game/turfs/open/floor/fancy_floor.dm

@@ -871,6 +871,7 @@
 	icon = 'icons/turf/space.dmi'
 	icon_state = "space"
 	floor_tile = /obj/item/stack/tile/fakespace
+	layer = SPACE_LAYER
 	plane = PLANE_SPACE
 	tiled_dirt = FALSE
 	damaged_dmi = 'icons/turf/space.dmi'

code/game/turfs/open/openspace.dm

@@ -10,6 +10,7 @@
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	pathing_pass_method = TURF_PATHING_PASS_PROC
 	plane = TRANSPARENT_FLOOR_PLANE
+	layer = SPACE_LAYER
 	rust_resistance = RUST_RESISTANCE_ABSOLUTE
 	var/can_cover_up = TRUE
 	var/can_build_on = TRUE