Adds ice tiles to cold pressurized turfs

code/LINDA/LINDA_turf_tile.dm

@@ -46,13 +46,12 @@
 	var/datum/gas_mixture/air
 	var/archived_cycle = 0
 	var/current_cycle = 0
+	var/icy = 0
 
 	var/obj/effect/hotspot/active_hotspot
 
 	var/temperature_archived //USED ONLY FOR SOLIDS
 
-	var/atmos_overlay_type = "" //current active overlay
-
 /turf/simulated/New()
 	..()
 
@@ -67,6 +66,8 @@
 
 		air.temperature = temperature
 
+		update_visuals()
+
 /turf/simulated/Destroy()
 	visibilityChanged()
 	if(active_hotspot)
@@ -209,8 +210,6 @@
 
 	air.react()
 
-	update_visuals()
-
 	if(air.temperature > FIRE_MINIMUM_TEMPERATURE_TO_EXIST)
 		hotspot_expose(air.temperature, CELL_VOLUME)
 		for(var/atom/movable/item in src)
@@ -221,6 +220,13 @@
 			if(consider_superconductivity(starting = 1))
 				remove = 0
 
+	if(air.temperature < T0C && air.return_pressure() > 10)
+		icy = 1
+	else
+		icy = 0
+
+	update_visuals()
+
 	if(!excited_group && remove == 1)
 		air_master.remove_from_active(src)
 
@@ -232,17 +238,14 @@
 	archived_cycle = air_master.current_cycle
 
 /turf/simulated/proc/update_visuals()
-	var/new_overlay_type = tile_graphic()
-	if (new_overlay_type == atmos_overlay_type)
-		return
-	var/atmos_overlay = get_atmos_overlay_by_name(atmos_overlay_type)
-	if (atmos_overlay)
-		overlays -= atmos_overlay
+	overlays = 0
+	if(icy)
+		overlays += icemaster
 
-	atmos_overlay = get_atmos_overlay_by_name(new_overlay_type)
+	var/new_overlay_type = tile_graphic()
+	var/atmos_overlay = get_atmos_overlay_by_name(new_overlay_type)
 	if (atmos_overlay)
 		overlays += atmos_overlay
-	atmos_overlay_type = new_overlay_type
 
 /turf/simulated/proc/get_atmos_overlay_by_name(var/name)
 	switch(name)

code/_globalvars/misc.dm

@@ -1,5 +1,6 @@
 var/global/obj/effect/overlay/plmaster = null
 var/global/obj/effect/overlay/slmaster = null
+var/global/obj/effect/overlay/icemaster = null
 
 // nanomanager, the manager for Nano UIs
 var/datum/nanomanager/nanomanager = new()

code/controllers/Processes/air.dm

@@ -140,4 +140,10 @@ var/global/datum/controller/process/air_system/air_master
 	slmaster.icon = 'icons/effects/tile_effects.dmi'
 	slmaster.icon_state = "sleeping_agent"
 	slmaster.layer = FLY_LAYER
-	slmaster.mouse_opacity = 0
+	slmaster.mouse_opacity = 0
+
+	icemaster = new /obj/effect/overlay()
+	icemaster.icon = 'icons/turf/overlays.dmi'
+	icemaster.icon_state = "snowfloor"
+	icemaster.layer = TURF_LAYER+0.1
+	icemaster.mouse_opacity = 0