Update SSOverlays (ported from Baystation) (#19051)

Our SSOverlays system is outdated, and is likely the cause of many of
the issues seen in #18895. It has also been linked to a massive server
performance decrease.

This brings an updated system from Baystation, hopefully with speed
increases.

Should be testmerged, ideally with #18895.

---------

Co-authored-by: Cody Brittain <cbrittain10@live.com>

code/game/objects/effects/decals/Cleanable/humans.dm

@@ -106,11 +106,11 @@
 				if(!S.blood_DNA)
 					S.blood_DNA = list()
 					S.blood_overlay.color = basecolor
-					S.add_overlay(S.blood_overlay)
+					S.AddOverlays(S.blood_overlay)
 				if(S.blood_overlay && S.blood_overlay.color != basecolor)
-					S.cut_overlay(S.blood_overlay, TRUE)
+					S.CutOverlays(S.blood_overlay, ATOM_ICON_CACHE_PROTECTED)
 					S.blood_overlay.color = basecolor
-					S.add_overlay(S.blood_overlay, TRUE)
+					S.AddOverlays(S.blood_overlay, ATOM_ICON_CACHE_PROTECTED)
 				if(blood_DNA)
 					S.blood_DNA |= blood_DNA.Copy()
 
@@ -217,8 +217,8 @@
 	blood.Blend(basecolor,ICON_MULTIPLY)
 
 	icon = blood
-	cut_overlays()
-	add_overlay(giblets)
+	ClearOverlays()
+	AddOverlays(giblets)
 
 /obj/effect/decal/cleanable/blood/gibs/up
 	random_icon_states = list("gib1", "gib2", "gib3", "gib4", "gib5", "gibup1","gibup1","gibup1")

code/game/objects/effects/decals/Cleanable/tracks.dm

@@ -127,7 +127,7 @@
 		update_icon()
 
 /obj/effect/decal/cleanable/blood/tracks/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	color = "#FFFFFF"
 	var/truedir = 0
 
@@ -157,7 +157,7 @@
 		track.fresh = 0
 		track.overlay = I
 		stack[stack_idx] = track
-		add_overlay(I)
+		AddOverlays(I)
 
 /obj/effect/decal/cleanable/blood/tracks/footprints
 	name = "wet footprints"

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

@@ -28,6 +28,6 @@
 		shadeOverlay.Blend(shade,ICON_ADD)
 		SSicon_cache.crayon_cache["[type]_s"] = shadeOverlay
 
-	add_overlay(list(mainOverlay, shadeOverlay))
+	AddOverlays(list(mainOverlay, shadeOverlay))
 
 	add_hiddenprint(usr)

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

@@ -7,5 +7,5 @@
 	var/turf/T = get_turf(src)
 	var/image/I = image(icon, icon_state = icon_state, dir = dir)
 	I.color = color
-	T.add_overlay(I, TRUE)	// Register it as priority so we don't lose it on icon update.
+	T.AddOverlays(I, ATOM_ICON_CACHE_PROTECTED)	// Register it as protected so we don't lose it on icon update.
 	qdel(src)

code/game/objects/effects/spiders.dm

@@ -62,7 +62,7 @@
 
 	if(prob(75))
 		var/image/web_overlay = image(icon, icon_state = "[initial(icon_state)]-overlay[pick(1, 2, 3)]", layer = ABOVE_HUMAN_LAYER)
-		add_overlay(web_overlay)
+		AddOverlays(web_overlay)
 
 /obj/effect/spider/stickyweb/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
 	if(air_group || height == 0)

code/game/objects/items.dm

@@ -270,11 +270,11 @@
 /obj/item/update_icon()
 	. = ..()
 	if(build_from_parts || has_accents)
-		cut_overlays()
+		ClearOverlays()
 	if(build_from_parts)
-		add_overlay(overlay_image(icon,"[icon_state]_[worn_overlay]", flags=RESET_COLOR)) //add the overlay w/o coloration of the original sprite
+		AddOverlays(overlay_image(icon,"[icon_state]_[worn_overlay]", flags=RESET_COLOR)) //add the overlay w/o coloration of the original sprite
 	if(has_accents)
-		add_overlay(overlay_image(icon, "[icon_state]_acc", accent_color, accent_flags))
+		AddOverlays(overlay_image(icon, "[icon_state]_acc", accent_color, accent_flags))
 
 /obj/item/device
 	icon = 'icons/obj/device.dmi'
@@ -784,7 +784,7 @@ var/list/global/slot_flags_enumeration = list(
 /obj/item/clean_blood()
 	. = ..()
 	if(blood_overlay)
-		cut_overlay(blood_overlay, TRUE)
+		CutOverlays(blood_overlay, TRUE)
 	if(istype(src, /obj/item/clothing/gloves))
 		var/obj/item/clothing/gloves/G = src
 		G.transfer_blood = 0
@@ -815,7 +815,7 @@ var/list/global/slot_flags_enumeration = list(
 	//apply the blood-splatter overlay if it isn't already in there
 	if(!blood_DNA.len)
 		blood_overlay.color = blood_color
-		add_overlay(blood_overlay, TRUE)	// Priority overlay so we don't lose it somehow.
+		AddOverlays(blood_overlay, TRUE)	// Priority overlay so we don't lose it somehow.
 
 	//if this blood isn't already in the list, add it
 	if(istype(M))

code/game/objects/items/airbubble.dm

@@ -492,15 +492,15 @@
 	return contains_body
 
 /obj/structure/closet/airbubble/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(ripped)
 		name = "ripped air bubble"
 		icon_state = "[icon_state]_ripped"
 	else
 		icon_state = "[initial(icon_state)][opened ? "_open" : ""]"
 	if(zipped)
-		add_overlay("[icon_state]_restrained")
-	add_overlay("pressure_[(use_internal_tank) ?("on") : ("off") ]")
+		AddOverlays("[icon_state]_restrained")
+	AddOverlays("pressure_[(use_internal_tank) ?("on") : ("off") ]")
 
 // Process transfer of air from the tank. Handle if it is ripped open.
 /obj/structure/closet/airbubble/proc/process_tank_give_air()

code/game/objects/items/crayons.dm

@@ -92,10 +92,10 @@
 	update_icon()
 
 /obj/item/pen/crayon/augment/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	var/image/crayon_tip = image('icons/obj/crayons.dmi', "crayonaugment_tip")
 	crayon_tip.color = colour
-	add_overlay(crayon_tip)
+	AddOverlays(crayon_tip)
 
 /obj/item/pen/crayon/augment/throw_at(atom/target, range, speed, mob/user)
 	user.drop_from_inventory(src)

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

@@ -104,10 +104,10 @@
 			. = TRUE
 
 /obj/item/aicard/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(carded_ai)
 		if (!carded_ai.control_disabled)
-			add_overlay("aicard-on")
+			AddOverlays("aicard-on")
 		if(carded_ai.stat)
 			icon_state = "aicard-404"
 		else

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

@@ -65,35 +65,35 @@
 		var/c_state = "battery[battery_level][contained_sprite ? slot_str_to_contained_flag(slot) : ""]"
 		var/image/battery_overlay = image(c_icon, c_state)
 		battery_overlay.appearance_flags = RESET_ALPHA
-		I.add_overlay(battery_overlay)
+		I.AddOverlays(battery_overlay)
 	if(breath_mask)
 		var/c_state = "mask_[mask_on ? "worn" : "idle"][contained_sprite ? slot_str_to_contained_flag(slot) : ""]"
 		var/image/mask_overlay = image(c_icon, c_state)
 		mask_overlay.appearance_flags = RESET_ALPHA
-		I.add_overlay(mask_overlay)
+		I.AddOverlays(mask_overlay)
 	if(tank)
 		if(tank_level)
 			var/c_state = "tank_indicator[tank_level][contained_sprite ? slot_str_to_contained_flag(slot) : ""]"
 			var/image/tank_level_overlay = image(c_icon, c_state)
 			tank_level_overlay.appearance_flags = RESET_ALPHA
-			I.add_overlay(tank_level_overlay)
+			I.AddOverlays(tank_level_overlay)
 		var/c_state = "tank_[tank_type][contained_sprite ? slot_str_to_contained_flag(slot) : ""]"
 		var/image/tank_overlay = image(c_icon, c_state)
 		tank_overlay.appearance_flags = RESET_ALPHA
-		I.add_overlay(tank_overlay)
+		I.AddOverlays(tank_overlay)
 	if(epp_active)
 		var/c_state = "epp_active[cpr_mode ? "_cpr" : ""][contained_sprite ? slot_str_to_contained_flag(slot) : ""]"
 		var/image/epp_overlay = image(c_icon, c_state)
 		epp_overlay.appearance_flags = RESET_ALPHA
-		I.add_overlay(epp_overlay)
+		I.AddOverlays(epp_overlay)
 	return I
 
 /obj/item/auto_cpr/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	item_state = "[cpr_mode ? "med_harness_cpr" : "[initial(item_state)]"]"
 
 	if(breath_mask)
-		add_overlay("mask_[mask_on ? "worn" : "idle"]")
+		AddOverlays("mask_[mask_on ? "worn" : "idle"]")
 	if(battery)
 		switch(battery.percent())
 			if(90 to INFINITY)	battery_level = 6
@@ -103,7 +103,7 @@
 			if(20 to 39)		battery_level = 2
 			if(05 to 19)		battery_level = 1
 			if(-INFINITY to 4)	battery_level = 0
-		add_overlay("battery[battery_level]")
+		AddOverlays("battery[battery_level]")
 	if(tank)
 		switch(tank.percent())
 			if(90 to INFINITY)	tank_level = 6
@@ -113,7 +113,7 @@
 			if(20 to 39)		tank_level = 2
 			if(05 to 19)		tank_level = 1
 			if(-INFINITY to 4)	tank_level = 0
-		add_overlay("tank_indicator[tank_level]")
+		AddOverlays("tank_indicator[tank_level]")
 
 		if(istype(tank, /obj/item/tank/emergency_oxygen/engi))
 			tank_type = "engi"
@@ -121,11 +121,11 @@
 			tank_type = "oxy"
 		else
 			tank_type = "other"
-		add_overlay("tank_[tank_type]")
+		AddOverlays("tank_[tank_type]")
 	if(epp_active)
-		add_overlay("epp_active")
+		AddOverlays("epp_active")
 	if(panel_open)
-		add_overlay("panel_open[battery ? "_battery" : ""]")
+		AddOverlays("panel_open[battery ? "_battery" : ""]")
 
 /obj/item/auto_cpr/mob_can_equip(mob/living/carbon/human/H, slot, disable_warning = 0, force = 0)
 	. = ..()

code/game/objects/items/devices/lighting/glowstick.dm

@@ -34,7 +34,7 @@
 	else if(on)
 		var/image/I = overlay_image(icon, "glowstick-overlay", color)
 		I.blend_mode = BLEND_ADD
-		add_overlay(I)
+		AddOverlays(I)
 		icon_state = "[initial(icon_state)]-on"
 		item_state = "[initial(icon_state)]-on"
 		set_light(brightness_on, flashlight_power, light_color)

code/game/objects/items/devices/lighting/lamp.dm

@@ -52,10 +52,10 @@
 		set_light(brightness_on, flashlight_power, light_color)
 	else
 		set_light(0)
-	cut_overlays()
+	ClearOverlays()
 	var/image/I = image(icon = icon, icon_state = "lavalamp-[on ? "on" : "off"]")
 	I.color = light_color
-	add_overlay(I)
+	AddOverlays(I)
 
 /obj/item/device/flashlight/lamp/lava/red
 	light_color = COLOR_RED

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

@@ -173,7 +173,7 @@
 
 /obj/item/device/lightreplacer/update_icon()
 	if(emagged)
-		add_overlay("emagged")
+		AddOverlays("emagged")
 
 
 /obj/item/device/lightreplacer/proc/Use(var/mob/user)

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

@@ -167,15 +167,15 @@
 				if (WT.use(2, user))
 					user.visible_message(SPAN_NOTICE("[user] starts welding the metal shell of [src]."), SPAN_NOTICE("You start [hacked ? "repairing" : "welding open"] the metal covering of [src]."))
 					playsound(loc, 'sound/items/Welder.ogg', 50, 1)
-					add_overlay("overlay_welding")
+					AddOverlays("overlay_welding")
 					if(WT.use_tool(src, user, 25, volume = 50))
 						to_chat(user, SPAN_NOTICE("You are able to [hacked ? "repair" : "weld through"] the metal shell of [src]."))
 						if (hacked) locked = 1
 						else locked = 0
 						hacked = !hacked
-						cut_overlay("overlay_welding")
+						CutOverlays("overlay_welding")
 					else
-						cut_overlay("overlay_welding")
+						CutOverlays("overlay_welding")
 					update_icon()
 				return TRUE
 
@@ -402,7 +402,7 @@
 	update_overlays()
 
 /obj/item/device/magnetic_lock/proc/update_overlays()
-	cut_overlays()
+	ClearOverlays()
 	switch (status)
 		if (STATUS_BROKEN)
 			icon_state = "broken"
@@ -410,16 +410,16 @@
 
 		if (STATUS_INACTIVE to STATUS_ACTIVE)
 			if (hacked)
-				add_overlay("overlay_hacked")
+				AddOverlays("overlay_hacked")
 			else if (locked)
-				add_overlay("overlay_locked")
+				AddOverlays("overlay_locked")
 			else
-				add_overlay("overlay_unlocked")
+				AddOverlays("overlay_unlocked")
 			switch (constructionstate)
 				if (0)
 					return
 				if (1 to 4)
-					add_overlay("overlay_deconstruct_[constructionstate]")
+					AddOverlays("overlay_deconstruct_[constructionstate]")
 
 /obj/item/device/magnetic_lock/proc/takedamage(var/damage)
 	if(invincible)
@@ -453,7 +453,7 @@
 	switch (status)
 		if (STATUS_INACTIVE to STATUS_ACTIVE)
 			if(istype(src, /obj/item/device/magnetic_lock/keypad))
-				add_overlay("overlay_keypad")
+				AddOverlays("overlay_keypad")
 
 /obj/item/device/magnetic_lock/keypad/ui_interact(mob/user, datum/tgui/ui)
 	ui = SStgui.try_update_ui(user, src, ui)

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

@@ -35,13 +35,13 @@
 	update_icon()
 
 /obj/item/device/memorywiper/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(anchored)
 		icon_state = "[initial(icon_state)]_opened"
 		if(attached)
-			add_overlay("wireout")
+			AddOverlays("wireout")
 		if(wiping)
-			add_overlay("screen")
+			AddOverlays("screen")
 	else
 		icon_state = initial(icon_state)
 

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

@@ -121,7 +121,7 @@
 			if(tracking_apc)
 				START_PROCESSING(SSprocessing, src)
 				apc_indicator = mutable_appearance(icon, "lost")
-				add_overlay(apc_indicator)
+				AddOverlays(apc_indicator)
 			else
 				STOP_PROCESSING(SSprocessing, src)
 				QDEL_NULL(apc_indicator)
@@ -169,7 +169,7 @@
 				apc_indicator.icon_state = "medium"
 			if(16 to INFINITY)
 				apc_indicator.icon_state = "far"
-	set_overlays(apc_indicator)
+	SetOverlays(apc_indicator)
 
 /obj/item/device/multitool/proc/wire(datum/integrated_io/io, mob/user)
 	if(!io.holder.assembly)

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

@@ -34,7 +34,7 @@
 
 /obj/item/device/paicard/Initialize()
 	. = ..()
-	add_overlay("pai_off")
+	AddOverlays("pai_off")
 	SSpai.all_pai_devices += src
 	update_light()
 
@@ -389,19 +389,19 @@
 
 /obj/item/device/paicard/proc/setPersonality(mob/living/silicon/pai/personality)
 	src.pai = personality
-	add_overlay("pai-happy")
+	AddOverlays("pai-happy")
 	playsound(src, 'sound/effects/pai/pai_restore.ogg', 75)
 
 /obj/item/device/paicard/proc/removePersonality()
 	src.pai = null
-	cut_overlays()
-	add_overlay("pai-off")
+	ClearOverlays()
+	AddOverlays("pai-off")
 
 /obj/item/device/paicard
 	var/current_emotion = 1
 /obj/item/device/paicard/proc/setEmotion(var/emotion)
 	if(pai)
-		cut_overlays()
+		ClearOverlays()
 		var/new_state
 		switch(emotion)
 			if(1) new_state = "pai-happy"
@@ -420,7 +420,7 @@
 			if(14) new_state = "pai-exclamation"
 			if(15) new_state = "pai-question"
 		if (new_state)
-			add_overlay(new_state)
+			AddOverlays(new_state)
 		current_emotion = emotion
 
 /obj/item/device/paicard/proc/alertUpdate()

code/game/objects/items/devices/radio/intercom.dm

@@ -431,19 +431,19 @@ pixel_x = 8;
 	..(dest)
 
 /obj/item/device/radio/intercom/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(!on)
 		icon_state = initial(icon_state)
 		set_light(FALSE)
 		return
 	else
-		add_overlay(screen_overlays["intercom_screen"])
-		add_overlay(screen_overlays["intercom_scanline"])
+		AddOverlays(screen_overlays["intercom_screen"])
+		AddOverlays(screen_overlays["intercom_scanline"])
 		set_light(1.4, 1.3, COLOR_CYAN)
 		if(broadcasting)
-			add_overlay(screen_overlays["intercom_b"])
+			AddOverlays(screen_overlays["intercom_b"])
 		if(listening)
-			add_overlay(screen_overlays["intercom_l"])
+			AddOverlays(screen_overlays["intercom_l"])
 
 /obj/item/device/radio/intercom/broadcasting/Initialize()
 	SHOULD_CALL_PARENT(FALSE)

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

@@ -472,10 +472,10 @@ BREATH ANALYZER
 	origin_tech = list(TECH_MAGNET = 4, TECH_BIO = 2)
 
 /obj/item/device/mass_spectrometer/adv/clear_blood_overlay()
-	cut_overlays()
+	ClearOverlays()
 
 /obj/item/device/mass_spectrometer/adv/add_blood_overlay(var/image/I)
-	add_overlay(I)
+	AddOverlays(I)
 
 /obj/item/device/reagent_scanner
 	name = "reagent scanner"

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

@@ -157,7 +157,7 @@
 	if(!istype(I))
 		qdel(src)
 		return
-	cut_overlays()
+	ClearOverlays()
 	var/mutable_appearance/MA = new(I)
 	MA.plane = EFFECTS_ABOVE_LIGHTING_PLANE
 	MA.appearance_flags = RESET_ALPHA
@@ -202,6 +202,6 @@
 	if(!istype(P))
 		qdel(src)
 		return
-	cut_overlays()
+	ClearOverlays()
 	if(P.info)
 		icon_state = "text[rand(1,3)]"

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

@@ -175,7 +175,7 @@
 	return ..()
 
 /obj/item/device/suit_cooling_unit/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(cover_open)
 		if(cell)
 			icon_state = "suitcooler1"
@@ -202,7 +202,7 @@
 			if(-INFINITY to 17)
 				battery_level = 5
 
-		add_overlay("battery-[battery_level]")
+		AddOverlays("battery-[battery_level]")
 		item_state = "coolingpack[battery_level]"
 
 	if(ismob(loc))

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

@@ -117,7 +117,7 @@
 			toggle = 1
 
 /obj/item/device/transfer_valve/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	underlays = null
 
 	if(!tank_one && !tank_two && !attached_device)
@@ -126,13 +126,13 @@
 	icon_state = "valve"
 
 	if(tank_one)
-		add_overlay("[tank_one.icon_state]")
+		AddOverlays("[tank_one.icon_state]")
 	if(tank_two)
 		var/icon/J = new(icon, icon_state = "[tank_two.icon_state]")
 		J.Shift(WEST, 13)
 		underlays += J
 	if(attached_device)
-		add_overlay("device")
+		AddOverlays("device")
 
 /obj/item/device/transfer_valve/proc/remove_tank(obj/item/tank/T, mob/user)
 	if(tank_one == T)

code/game/objects/items/draftingchalk.dm

@@ -114,6 +114,6 @@
 	update_icon()
 
 /obj/item/storage/box/fancy/crayons/chalkbox/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	for(var/obj/item/pen/drafting/chalk in contents)
-		add_overlay("[chalk.colorName]")
+		AddOverlays("[chalk.colorName]")

code/game/objects/items/glassjar.dm

@@ -145,7 +145,7 @@
 
 /obj/item/glass_jar/update_icon() // Also updates name and desc
 	underlays.Cut()
-	cut_overlays()
+	ClearOverlays()
 	switch(contains)
 		if(JAR_NOTHING)
 			name = initial(name)

code/game/objects/items/holomenu.dm

@@ -34,7 +34,7 @@
 	update_icon()
 
 /obj/item/holomenu/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(anchored)
 		set_light(2)
 		if(rave_mode)
@@ -46,11 +46,11 @@
 			holo_lights.color = null
 			holo_text.color = null
 			holo_border.color = null
-		add_overlay(holo_lights)
+		AddOverlays(holo_lights)
 		if(length(menu_text))
-			add_overlay(holo_text)
+			AddOverlays(holo_text)
 		if(border_on)
-			add_overlay(holo_border)
+			AddOverlays(holo_border)
 	else
 		set_light(0)
 

code/game/objects/items/ipc_overloaders.dm

@@ -284,12 +284,12 @@
 
 /obj/item/storage/overloader/update_icon()
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	var/obj/item/ipc_overloader/overloader = locate() in contents
 	if(overloader)
-		add_overlay(image(overloader.icon, null, overloader.icon_state, sealed ? layer - 0.01 : layer + 0.01))
+		AddOverlays(image(overloader.icon, null, overloader.icon_state, sealed ? layer - 0.01 : layer + 0.01))
 		if(!sealed)
-			add_overlay(image(icon, null, "box-overlay", layer + 0.02))
+			AddOverlays(image(icon, null, "box-overlay", layer + 0.02))
 	if(!sealed)
 		icon_state = "box-open"
 

code/game/objects/items/items_icon.dm

@@ -46,9 +46,9 @@ var/list/mob_icon_icon_states = list()
 		I = overlay_image(mob_overlay_icon, color = color, flags = RESET_COLOR|RESET_ALPHA)
 	var/image/additional_parts = build_additional_parts(H, mob_icon, slot)
 	if(additional_parts)
-		I.add_overlay(additional_parts)
+		I.AddOverlays(additional_parts)
 	if(has_accents)
-		I.add_overlay(overlay_image(icon, "[UNDERSCORE_OR_NULL(src.icon_species_tag)][item_state][contained_sprite ? slot_str_to_contained_flag(slot) : ""]_acc", accent_color, accent_flags))
+		I.AddOverlays(overlay_image(icon, "[UNDERSCORE_OR_NULL(src.icon_species_tag)][item_state][contained_sprite ? slot_str_to_contained_flag(slot) : ""]_acc", accent_color, accent_flags))
 	var/offset_x = worn_x_dimension
 	var/offset_y = worn_y_dimension
 	center_image(I, offset_x, offset_y)

code/game/objects/items/knitting.dm

@@ -59,9 +59,9 @@
 			yarn_overlay.color = ball.color
 		else
 			yarn_overlay.appearance_flags = RESET_COLOR
-		add_overlay(yarn_overlay)
+		AddOverlays(yarn_overlay)
 	else
-		cut_overlays()
+		ClearOverlays()
 	update_held_icon()
 
 /obj/item/knittingneedles/attackby(obj/item/attacking_item, mob/user)

code/game/objects/items/shooting_range.dm

@@ -24,7 +24,7 @@
 			return TRUE
 		var/obj/item/weldingtool/WT = attacking_item
 		if(WT.use(0, user))
-			cut_overlays()
+			ClearOverlays()
 			LAZYCLEARLIST(bullet_holes)
 			icon = initial(icon)
 			hp = initial(hp)
@@ -97,7 +97,7 @@
 			virtual_icon.DrawBox(null, B.b2x, B.b2y1,  B.b2x, B.b2y2) // vertical line, top to bottom
 
 
-		add_overlay(bmark) // add the decal
+		AddOverlays(bmark) // add the decal
 		icon = virtual_icon // apply bullet_holes over decals
 		return
 

code/game/objects/items/skrell.dm

@@ -61,7 +61,7 @@
 	. = ..()
 	if(!glow_state)
 		glow_state = make_screen_overlay(icon, icon_state)
-	add_overlay(glow_state)
+	AddOverlays(glow_state)
 
 /obj/effect/temp_visual/constellation/attackby(obj/item/attacking_item, mob/user)
 	visible_message("<span class='notice'>\The [src] vanishes!</span>")
@@ -151,10 +151,10 @@
 	update_icon()
 
 /obj/item/skrell_projector/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(working)
 		var/image/overlay = overlay_image(icon, "projector_light", light_color, RESET_COLOR)
-		add_overlay(overlay)
+		AddOverlays(overlay)
 
 /obj/item/skrell_projector/process()
 	if(!selected_world)

code/game/objects/items/stacks/medical.dm

@@ -106,7 +106,7 @@ Contains:
 	if(!automatic_charge_overlays)	//Checks if the item has this feature enabled
 		return	//If it does not, do nothing
 	var/ratio = CEILING(clamp(amount / max_amount, 0, 1) * charge_sections, 1)
-	cut_overlays()
+	ClearOverlays()
 	var/iconState = "[icon_state]_charge"
 	if(!amount)	//Checks if there are still charges left in the item
 		return //If it does not, do nothing, as the overlays have been cut before this already.
@@ -114,7 +114,7 @@ Contains:
 		var/mutable_appearance/charge_overlay = mutable_appearance(icon, iconState)
 		for(var/i = ratio, i >= 1, i--)
 			charge_overlay.pixel_x = charge_x_offset * (i - 1)
-			add_overlay(charge_overlay)
+			AddOverlays(charge_overlay)
 
 // Bruise Pack.
 /obj/item/stack/medical/bruise_pack

code/game/objects/items/toys.dm

@@ -256,9 +256,9 @@
 	..()
 	if(status == BALLOON_BURST)
 		worn_overlay = null
-	cut_overlay()
+	CutOverlays()
 	if(worn_overlay)
-		add_overlay(overlay_image(icon, "[initial(icon_state)]_[worn_overlay]", flags=RESET_COLOR))
+		AddOverlays(overlay_image(icon, "[initial(icon_state)]_[worn_overlay]", flags=RESET_COLOR))
 
 #undef BALLOON_NORMAL
 #undef BALLOON_BLOW

code/game/objects/items/vaurca.dm

@@ -115,10 +115,10 @@
 	update_icon()
 
 /obj/item/skrell_projector/vaurca_projector/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(working)
 		var/image/overlay = overlay_image(icon, "zora_projector_light", light_color, RESET_COLOR)
-		add_overlay(overlay)
+		AddOverlays(overlay)
 
 /obj/item/skrell_projector/vaurca_projector/process()
 	if(!selected_world || !possible_messages)

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

@@ -112,10 +112,10 @@
 	check_obfuscation()
 
 /obj/item/card/id/syndicate/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(electronic_warfare)
 		var/mutable_appearance/electro_overlay = mutable_appearance(icon, "electronic_warfare")
-		add_overlay(electro_overlay)
+		AddOverlays(electro_overlay)
 
 /obj/item/card/id/syndicate/proc/check_obfuscation()
 	if(electronic_warfare)

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

@@ -23,11 +23,11 @@
 		update_icon()
 
 /obj/item/clothing/mask/chewable/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(wrapped)
 		var/mutable_appearance/base_overlay = mutable_appearance(icon, "[initial(icon_state)]_wrapper")
 		base_overlay.appearance_flags = RESET_COLOR
-		add_overlay(base_overlay)
+		AddOverlays(base_overlay)
 
 /obj/item/clothing/mask/chewable/Initialize()
 	create_reagents(chem_volume) // making the cigarrete a chemical holder with a maximum volume of 15
@@ -236,12 +236,12 @@
 		spitout(0)
 
 /obj/item/clothing/mask/chewable/candy/lolli/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	var/mutable_appearance/base_overlay = mutable_appearance(icon, "[initial(icon_state)]_stick")
 	base_overlay.appearance_flags = RESET_COLOR
-	add_overlay(base_overlay)
+	AddOverlays(base_overlay)
 	if(wrapped)
-		add_overlay("[initial(icon_state)]_wrapper")
+		AddOverlays("[initial(icon_state)]_wrapper")
 
 /obj/item/clothing/mask/chewable/candy/lolli/Initialize()
 	. = ..()

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

@@ -16,14 +16,14 @@
 	pickup_sound = 'sound/items/pickup/screwdriver.ogg'
 
 /obj/item/lipstick/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(open)
 		worn_overlay = "open_overlay"
 		worn_overlay_color = lipstick_color
 		icon_state = "[initial(icon_state)]_open"
 		var/image/stick_overlay = image('icons/obj/cosmetics.dmi', null, "[initial(icon_state)]_open_overlay")
 		stick_overlay.color = lipstick_color
-		add_overlay(stick_overlay)
+		AddOverlays(stick_overlay)
 	else
 		icon_state = initial(icon_state)
 		worn_overlay = initial(worn_overlay)

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

@@ -65,19 +65,19 @@
 		location.hotspot_expose(700, 2)
 
 /obj/item/flamethrower/update_icon()
-	cut_overlays()
-	add_overlay("+[initial(welding_tool.icon_state)]")
+	ClearOverlays()
+	AddOverlays("+[initial(welding_tool.icon_state)]")
 
 	if(igniter)
-		add_overlay("+igniter[secured]")
+		AddOverlays("+igniter[secured]")
 
 	if(istype(gas_tank, /obj/item/tank/phoron))
-		add_overlay("+phoron_tank")
+		AddOverlays("+phoron_tank")
 	else if(istype(gas_tank, /obj/item/tank/hydrogen))
-		add_overlay("+hydro_tank")
+		AddOverlays("+hydro_tank")
 
 	if(lit)
-		add_overlay("+lit")
+		AddOverlays("+lit")
 		set_light(1.4, 2)
 		item_state = "flamethrower_1"
 	else

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

@@ -167,7 +167,7 @@
 	if(build_from_parts) //random colors!
 		if(!color)
 			color = pick(COLOR_RED, COLOR_BLUE, COLOR_LIME, COLOR_ORANGE, COLOR_WHITE, COLOR_PINK, COLOR_YELLOW, COLOR_CYAN)
-		add_overlay(overlay_image(icon, "[initial(icon_state)]_end", flags=RESET_COLOR))
+		AddOverlays(overlay_image(icon, "[initial(icon_state)]_end", flags=RESET_COLOR))
 
 /obj/item/handcuffs/cable/attack_self(mob/user)
 	legcuff = !legcuff

code/game/objects/items/weapons/implants/implantcase.dm

@@ -30,11 +30,11 @@
 
 
 /obj/item/implantcase/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if (imp)
 		var/overlay_icon_state = "implantstorage_[imp.implant_icon]"
 		var/mutable_appearance/overlay_implant_icon = mutable_appearance(icon, overlay_icon_state)
-		add_overlay(overlay_implant_icon)
+		AddOverlays(overlay_implant_icon)
 
 /obj/item/implantcase/attackby(obj/item/attacking_item, mob/user)
 	if (attacking_item.ispen())

code/game/objects/items/weapons/implants/implanter.dm

@@ -16,12 +16,12 @@
 	update_icon()
 
 /obj/item/implanter/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	icon_state = "implanter-[imp ? "1" : "0"]"
 	if (imp)
 		var/mutable_appearance/overlay_implant_icon = mutable_appearance(icon, "implanter-overlay")
 		overlay_implant_icon.color = imp.implant_color
-		add_overlay(overlay_implant_icon)
+		AddOverlays(overlay_implant_icon)
 
 /obj/item/implanter/attackby(obj/item/attacking_item, mob/user)
 	if(!imp && istype(attacking_item, /obj/item/implant) && user.unEquip(attacking_item, src))

code/game/objects/items/weapons/implants/implantpad.dm

@@ -12,13 +12,13 @@
 	var/listening = TRUE
 
 /obj/item/implantpad/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	icon_state = "implantpad-[case ? "1" : "0"]"
 	if(case?.imp)
 		var/obj/item/implant/caseimplant = case.imp
 		var/implant_overlay_icon_state = "implantstorage_[caseimplant.implant_icon]"
 		var/mutable_appearance/implant_case_implant_overlay = mutable_appearance(icon, implant_overlay_icon_state)
-		add_overlay(implant_case_implant_overlay)
+		AddOverlays(implant_case_implant_overlay)
 
 
 /obj/item/implantpad/attack_hand(mob/user)

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

@@ -62,7 +62,7 @@
 	var/image/I = image(icon, null, "wiredrod_cable")
 	I.appearance_flags = RESET_COLOR
 	I.color = cable_color
-	add_overlay(I)
+	AddOverlays(I)
 
 /obj/item/material/wirerod/attackby(obj/item/attacking_item, mob/user)
 	..()

code/game/objects/items/weapons/material/ashtray.dm

@@ -39,20 +39,20 @@
 
 /obj/item/material/ashtray/update_icon()
 	color = null
-	cut_overlays()
+	ClearOverlays()
 	var/list/ashtray_cache = SSicon_cache.ashtray_cache
 	var/cache_key = "base-[material.name]"
 	if(!ashtray_cache[cache_key])
 		var/image/I = image('icons/obj/ashtray.dmi',"ashtray")
 		I.color = material.icon_colour
 		ashtray_cache[cache_key] = I
-	add_overlay(ashtray_cache[cache_key])
+	AddOverlays(ashtray_cache[cache_key])
 
 	if (contents.len == max_butts)
-		add_overlay("ashtray_full")
+		AddOverlays("ashtray_full")
 		desc = "It's stuffed full."
 	else if (contents.len > max_butts/2)
-		add_overlay("ashtray_half")
+		AddOverlays("ashtray_half")
 		desc = "It's half-filled."
 	else
 		desc = "An ashtray made of [material.display_name]."

code/game/objects/items/weapons/material/kitchen.dm

@@ -58,7 +58,7 @@
 			is_liquid = FALSE
 		else
 			playsound(user.loc, 'sound/items/eatfood.ogg', rand(10, 50), 1)
-		cut_overlays()
+		ClearOverlays()
 		return
 	else
 		to_chat(user, SPAN_WARNING("You don't have anything on \the [src].")) 	//if we have help intent and no food scooped up DON'T STAB OURSELVES WITH THE FORK)
@@ -70,7 +70,7 @@
 		reagents.clear_reagents()
 		is_liquid = FALSE
 		loaded = null
-		cut_overlays()
+		ClearOverlays()
 	return
 
 /obj/item/material/kitchen/utensil/verb/bite_size()

code/game/objects/items/weapons/material/misc.dm

@@ -102,7 +102,7 @@
 	if(build_from_parts)
 		var/image/I = image(icon, icon_state = "machete_handle")
 		I.color = pick(COLOR_BLUE, COLOR_RED, COLOR_CYAN, COLOR_BLACK, COLOR_AMBER, COLOR_GREEN, COLOR_OLIVE, COLOR_GUNMETAL, COLOR_DARK_BLUE_GRAY)
-		add_overlay(I)
+		AddOverlays(I)
 
 /obj/item/material/hatchet/machete/unbreakable
 	unbreakable = TRUE

code/game/objects/items/weapons/material/twohanded.dm

@@ -277,7 +277,7 @@
 		usr.drop_from_inventory(attacking_item, HS)
 		var/mutable_appearance/MA = new(attacking_item)
 		MA.layer = FLOAT_LAYER
-		HS.add_overlay(MA)
+		HS.AddOverlays(MA)
 		HS.name = "[attacking_item.name] on a spear"
 		HS.material = material.name
 		qdel(src)

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

@@ -30,13 +30,13 @@
 	update_icon()
 
 /obj/item/reagent_containers/glass/paint/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(!is_open_container())
-		add_overlay("paint_lid")
+		AddOverlays("paint_lid")
 	else if(reagents.total_volume)
 		var/image/I = image(icon, "paint_full")
 		I.color = reagents.get_color()
-		add_overlay(I)
+		AddOverlays(I)
 
 /obj/item/reagent_containers/glass/paint/on_reagent_change()
 	update_icon()

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

@@ -193,11 +193,11 @@ var/list/tape_roll_applications = list()
 
 		if(tape_roll_applications[F] & direction) // hazard_overlay in F.overlays wouldn't work.
 			user.visible_message("[user] uses the adhesive of \the [src] to remove area markings from \the [F].", "You use the adhesive of \the [src] to remove area markings from \the [F].")
-			F.cut_overlay(hazard_overlay, TRUE)
+			F.CutOverlays(hazard_overlay, ATOM_ICON_CACHE_PROTECTED)
 			tape_roll_applications[F] &= ~direction
 		else
 			user.visible_message("[user] applied \the [src] on \the [F] to create area markings.", "You apply \the [src] on \the [F] to create area markings.")
-			F.add_overlay(hazard_overlay, TRUE)
+			F.AddOverlays(hazard_overlay, ATOM_ICON_CACHE_PROTECTED)
 			tape_roll_applications[F] |= direction
 		return
 

code/game/objects/items/weapons/storage/backpack.dm

@@ -947,7 +947,7 @@
 /obj/item/storage/backpack/cloak/get_mob_overlay(var/mob/living/carbon/human/human, var/mob_icon, var/mob_state, var/slot)
 	var/image/I = ..()
 	var/image/cape_backing = image(mob_icon, null, "[icon_state]_backing", MOB_SHADOW_LAYER)
-	I.add_overlay(cape_backing)
+	I.AddOverlays(cape_backing)
 	return I
 
 /obj/item/storage/backpack/cloak/sedantis

code/game/objects/items/weapons/storage/belt.dm

@@ -22,10 +22,10 @@
 		M.update_inv_belt()
 
 /obj/item/storage/belt/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(content_overlays)
 		for(var/obj/item/I in contents)
-			add_overlay(I.get_belt_overlay())
+			AddOverlays(I.get_belt_overlay())
 	..()
 
 /obj/item/storage/belt/build_additional_parts(H, mob_icon, slot)
@@ -44,7 +44,7 @@
 		var/image/belt_item_image = image(c_icon, c_state)
 		belt_item_image.color = i.color
 		belt_item_image.appearance_flags = RESET_ALPHA
-		I.add_overlay(belt_item_image)
+		I.AddOverlays(belt_item_image)
 	return I
 
 /obj/item/storage/belt/verb/toggle_layer()

code/game/objects/items/weapons/storage/boxes.dm

@@ -50,7 +50,7 @@
 	if(ispath(src.trash))
 		desc_info += "This can be crumpled up into a trash item when empty, or forcibly crumpled on harm intent. "
 	if(illustration)
-		add_overlay(illustration)
+		AddOverlays(illustration)
 
 /obj/item/storage/box/proc/damage(var/severity)
 	health -= severity

code/game/objects/items/weapons/storage/business_card.dm

@@ -9,7 +9,7 @@
 	can_hold = list(/obj/item/paper/business_card)
 
 /obj/item/storage/business_card_holder/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	var/overlay_type
 	if(length(contents))
 		var/obj/O = contents[1]
@@ -22,7 +22,7 @@
 			card_overlay.color = O.color
 		else
 			card_overlay.appearance_flags = RESET_COLOR
-		add_overlay(card_overlay)
+		AddOverlays(card_overlay)
 
 /obj/item/storage/business_card_holder/wood
 	icon_state = "holder_wood"
@@ -44,8 +44,8 @@
 /obj/item/paper/business_card/update_icon()
 	. = ..()
 	if(worn_overlay)
-		cut_overlays()
-		add_overlay(overlay_image(icon, worn_overlay, flags=RESET_COLOR))
+		ClearOverlays()
+		AddOverlays(overlay_image(icon, worn_overlay, flags=RESET_COLOR))
 
 /obj/item/paper/business_card/attack_self(mob/living/user)
 	if(last_flash <= world.time - 20)

code/game/objects/items/weapons/storage/fancy.dm

@@ -63,7 +63,7 @@
 			icon_state = "[initial(icon_state)][src.opened]"
 			..()
 	else
-		cut_overlays()
+		ClearOverlays()
 		icon_state = "[initial(icon_state)]" // closed
 	..()
 
@@ -102,10 +102,10 @@
 /obj/item/storage/box/fancy/donut/update_icon() // One of the few unique update_icon()s, due to having to store both regular and sprinkled donuts.
 	. = ..()
 	if(opened)
-		cut_overlays()
+		ClearOverlays()
 		var/i = 0
 		for(var/obj/item/reagent_containers/food/snacks/donut/D in contents)
-			add_overlay("[i][D.overlay_state]")
+			AddOverlays("[i][D.overlay_state]")
 			i++
 
 /obj/item/storage/box/fancy/donut/empty
@@ -221,10 +221,10 @@
 
 /obj/item/storage/box/fancy/crayons/update_icon()
 	. = ..()
-	cut_overlays()
-	add_overlay("crayonbox")
+	ClearOverlays()
+	AddOverlays("crayonbox")
 	for(var/obj/item/pen/crayon/crayon in contents)
-		add_overlay("[crayon.colourName]")
+		AddOverlays("[crayon.colourName]")
 
 /obj/item/storage/box/fancy/crayons/attackby(obj/item/attacking_item, mob/user)
 	if(istype(attacking_item, /obj/item/pen/crayon))
@@ -467,13 +467,13 @@
 	. = ..()
 	var/total_contents = src.contents.len - itemremoved
 	src.icon_state = "vialbox[total_contents]"
-	cut_overlays()
+	ClearOverlays()
 	if (!broken)
-		add_overlay("led[locked]")
+		AddOverlays("led[locked]")
 		if(locked)
-			add_overlay("cover")
+			AddOverlays("cover")
 	else
-		add_overlay("ledb")
+		AddOverlays("ledb")
 
 /obj/item/storage/lockbox/vials/attackby(attacking_item, mob/user)
 	..()
@@ -527,7 +527,7 @@
 	update_icon()
 
 /obj/item/pizzabox/update_icon()
-	cut_overlays()
+	ClearOverlays()
 
 	// Set appropriate description
 	if( open && pizza )
@@ -555,7 +555,7 @@
 		if( pizza )
 			var/image/pizzaimg = image(pizza.icon, pizza.icon_state)
 			pizzaimg.pixel_y = -2
-			add_overlay(pizzaimg)
+			AddOverlays(pizzaimg)
 
 		return
 	else
@@ -572,7 +572,7 @@
 		if( doimgtag )
 			var/image/tagimg = image(icon, icon_state = "pizzabox_tag")
 			tagimg.pixel_y = boxes.len * 3
-			add_overlay(tagimg)
+			AddOverlays(tagimg)
 
 	icon_state = "pizzabox[boxes.len+1]"
 

code/game/objects/items/weapons/storage/secure.dm

@@ -105,15 +105,15 @@
 				src.l_set = 1
 			else if ((src.code == src.l_code) && (src.emagged == 0) && (src.l_set == 1))
 				src.locked = 0
-				cut_overlays()
-				add_overlay(icon_opened)
+				ClearOverlays()
+				AddOverlays(icon_opened)
 				src.code = null
 			else
 				src.code = "ERROR"
 		else
 			if ((href_list["type"] == "R") && (src.emagged == 0) && (!src.l_setshort))
 				src.locked = 1
-				cut_overlays()
+				ClearOverlays()
 				src.code = null
 				src.close(usr)
 			else
@@ -130,10 +130,10 @@
 /obj/item/storage/secure/emag_act(var/remaining_charges, var/mob/user, var/feedback)
 	if(!emagged)
 		emagged = 1
-		add_overlay(icon_sparking)
+		AddOverlays(icon_sparking)
 		sleep(6)
-		cut_overlays()
-		add_overlay(icon_locking)
+		ClearOverlays()
+		AddOverlays(icon_locking)
 		locked = 0
 		to_chat(user, (feedback ? feedback : "You short out the lock of \the [src]."))
 		return 1

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

@@ -360,12 +360,12 @@
 			ND.sample_object.maptext = SMALL_FONTS(7, "[(ND.number > 1)? "[ND.number]" : ""]")
 			ND.sample_object.hud_layerise()
 			if(display_contents_initials)
-				ND.sample_object.cut_overlays() // a limitation of this code is that overlays get blasted off the item, since we need to add one to add the second maptext. woe is me
+				ND.sample_object.ClearOverlays() // a limitation of this code is that overlays get blasted off the item, since we need to add one to add the second maptext. woe is me
 				var/object_initials = handle_name_initials(ND.sample_object.name)
 				var/image/name_overlay = image(null)
 				name_overlay.maptext = SMALL_FONTS(7, object_initials)
 				name_overlay.maptext_x = 22 - ((length(object_initials) - 1) * 6)
-				ND.sample_object.add_overlay(name_overlay)
+				ND.sample_object.AddOverlays(name_overlay)
 			cx++
 			if (cx > (4+cols))
 				cx = 4
@@ -395,7 +395,7 @@
 	var/stored_cap_width = 4 //length of sprite for start and end of the box representing the stored item
 	var/storage_width = min( round( 224 * max_storage_space/baseline_max_storage_space ,1) ,284) //length of sprite for the box representing total storage space
 
-	storage_start.cut_overlays()
+	storage_start.ClearOverlays()
 
 	var/matrix/M = matrix()
 	M.Scale((storage_width-storage_cap_width*2+3)/32,1)
@@ -439,7 +439,7 @@
 		O.hud_layerise()
 
 	if (!defer_overlays)
-		storage_start.compile_overlays()
+		storage_start.UpdateOverlays()
 
 	closer.screen_loc = "4:[storage_width+19],2:16"
 	return
@@ -654,7 +654,7 @@
 	if(W.maptext)
 		W.maptext = ""
 	if(display_contents_initials)
-		W.cut_overlays()
+		W.ClearOverlays()
 	W.on_exit_storage(src)
 	update_icon()
 	return TRUE

code/game/objects/items/weapons/storage/wallets.dm

@@ -79,7 +79,7 @@
 			update_icon()
 
 /obj/item/storage/wallet/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	worn_overlay = "fasteners"
 	if(front_id)
 		if(("[icon_state]-open") in icon_states(icon))
@@ -89,10 +89,10 @@
 		if(("[initial(icon_state)]-[front_id.icon_state]") in icon_states(icon))
 			tiny_state = "[initial(icon_state)]-[front_id.icon_state]"
 		var/image/tiny_image = overlay_image(icon, icon_state = tiny_state, flags = RESET_COLOR)
-		add_overlay(tiny_image)
+		AddOverlays(tiny_image)
 		if(("[initial(icon_state)]-film") in icon_states(icon))
 			var/image/film_image = overlay_image(icon, "[initial(icon_state)]-film", flags = RESET_COLOR)
-			add_overlay(film_image)
+			AddOverlays(film_image)
 	else
 		icon_state = "[initial(icon_state)]"
 		. = ..()
@@ -205,16 +205,16 @@
 	. = ..()
 	if(("[initial(icon_state)]-film") in icon_states(icon))
 		var/image/film_image = overlay_image(icon, "[initial(icon_state)]-film", flags = RESET_COLOR)
-		add_overlay(film_image)
+		AddOverlays(film_image)
 
 /obj/item/storage/wallet/lanyard/get_mob_overlay(mob/living/carbon/human/H, mob_icon, mob_state, slot)
 	var/image/I = ..()
 	if(front_id)
-		I.add_overlay(image('icons/mob/lanyard_overlays.dmi', icon_state = "lanyard-[front_id_overlay_state]"))
+		I.AddOverlays(image('icons/mob/lanyard_overlays.dmi', icon_state = "lanyard-[front_id_overlay_state]"))
 	else
 		if(!plastic_film)
 			plastic_film = image('icons/mob/lanyard_overlays.dmi', icon_state = "[plastic_film_overlay_state]")
-		I.add_overlay(plastic_film)
+		I.AddOverlays(plastic_film)
 	return I
 
 // wallet subtypes

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

@@ -254,7 +254,7 @@
 	if(!cable_color)
 		cable_color = COLOR_RED
 	I.color = cable_color
-	add_overlay(I)
+	AddOverlays(I)
 
 /obj/item/melee/baton/stunrod
 	name = "stunrod"

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

@@ -226,7 +226,7 @@
 	)
 
 /obj/item/storage/box/fancy/tray/update_icon()
-	cut_overlays()
+	ClearOverlays()
 
 	var/list/types_and_overlays = list(
 		/obj/item/surgery/bonesetter = "tray_bonesetter",
@@ -248,7 +248,7 @@
 	)
 	for (var/obj/item/W in contents)
 		if (types_and_overlays[W.type])
-			add_overlay(types_and_overlays[W.type])
+			AddOverlays(types_and_overlays[W.type])
 			types_and_overlays -= W.type
 
 /obj/item/storage/box/fancy/tray/fill()

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

@@ -77,13 +77,13 @@
 	add_fingerprint(user)
 
 	if(blood_overlay && blood_DNA && (blood_DNA.len >= 1)) //updates blood overlay, if any
-		cut_overlay(blood_overlay, TRUE)
+		CutOverlays(blood_overlay, ATOM_ICON_CACHE_PROTECTED)
 		var/icon/I = new /icon(src.icon, src.icon_state)
 		I.Blend(new /icon('icons/effects/blood.dmi', rgb(255,255,255)),ICON_ADD)
 		I.Blend(new /icon('icons/effects/blood.dmi', "itemblood"),ICON_MULTIPLY)
 		blood_overlay = image(I)
 		blood_overlay.color = blood_color
-		add_overlay(blood_overlay, TRUE)
+		AddOverlays(blood_overlay, ATOM_ICON_CACHE_PROTECTED)
 		update_icon()
 
 	return

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

@@ -226,9 +226,9 @@
 		return
 
 	last_gauge_pressure = gauge_pressure
-	cut_overlays()
+	ClearOverlays()
 	// SSoverlay will handle icon caching.
-	add_overlay("[gauge_icon][(gauge_pressure == -1) ? "overload" : gauge_pressure]")
+	AddOverlays("[gauge_icon][(gauge_pressure == -1) ? "overload" : gauge_pressure]")
 
 /obj/item/tank/proc/percent()
 	var/gauge_pressure = 0

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

@@ -75,7 +75,7 @@
 	. = ..()
 	if(build_from_parts) //random colors!
 		color = pick(COLOR_BLUE, COLOR_RED, COLOR_PURPLE, COLOR_BROWN, COLOR_GREEN, COLOR_CYAN, COLOR_YELLOW)
-		add_overlay(overlay_image(icon, "[initial(icon_state)]_[worn_overlay]", flags=RESET_COLOR))
+		AddOverlays(overlay_image(icon, "[initial(icon_state)]_[worn_overlay]", flags=RESET_COLOR))
 
 /obj/item/screwdriver/update_icon()
 	var/matrix/tf = matrix()
@@ -88,7 +88,7 @@
 	var/mutable_appearance/body = mutable_appearance('icons/obj/clothing/belt_overlays.dmi', "screwdriver")
 	var/mutable_appearance/head = mutable_appearance('icons/obj/clothing/belt_overlays.dmi', "screwdriver_head")
 	body.color = color
-	head.add_overlay(body)
+	head.AddOverlays(body)
 	return head
 
 /obj/item/screwdriver/pickup(mob/user)
@@ -153,7 +153,7 @@
 	. = ..()
 	if(build_from_parts)
 		color = pick(color_options)
-		add_overlay(overlay_image(icon, "[initial(icon_state)]_[worn_overlay]", flags=RESET_COLOR))
+		AddOverlays(overlay_image(icon, "[initial(icon_state)]_[worn_overlay]", flags=RESET_COLOR))
 
 /obj/item/wirecutters/update_icon()
 	var/matrix/tf = matrix()
@@ -166,7 +166,7 @@
 	var/mutable_appearance/body = mutable_appearance('icons/obj/clothing/belt_overlays.dmi', "wirecutters")
 	var/mutable_appearance/head = mutable_appearance('icons/obj/clothing/belt_overlays.dmi', "wirecutters_head")
 	body.color = color
-	head.add_overlay(body)
+	head.AddOverlays(body)
 	return head
 
 /obj/item/wirecutters/pickup(mob/user)
@@ -306,13 +306,13 @@
 /obj/item/weldingtool/use_tool(atom/target, mob/living/user, delay, amount, volume, datum/callback/extra_checks)
 	var/image/welding_sparks = image('icons/effects/effects.dmi', welding_state)
 	welding_sparks.plane = EFFECTS_ABOVE_LIGHTING_PLANE
-	target.add_overlay(welding_sparks)
+	target.AddOverlays(welding_sparks)
 	. = ..()
-	target.cut_overlay(welding_sparks)
+	target.CutOverlays(welding_sparks)
 
 /obj/item/weldingtool/proc/update_torch()
 	if(welding)
-		add_overlay("[initial(icon_state)]-on")
+		AddOverlays("[initial(icon_state)]-on")
 		item_state = "[initial(item_state)]1"
 	else
 		item_state = "[initial(item_state)]"
@@ -325,11 +325,11 @@
 		set_light(0)
 
 /obj/item/weldingtool/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(change_icons)
 		var/ratio = get_fuel() / max_fuel
 		ratio = CEILING(ratio*4, 1) * 25
-		add_overlay("[initial(icon_state)][ratio]")
+		AddOverlays("[initial(icon_state)][ratio]")
 	update_torch()
 	var/mob/M = loc
 	if(istype(M))
@@ -582,7 +582,7 @@
 		to_chat(user, SPAN_NOTICE("You install \the [attacking_item] into \the [src]."))
 		eyeshield = attacking_item
 		produces_flash = FALSE
-		add_overlay("eyeshield_attached", TRUE)
+		AddOverlays("eyeshield_attached", ATOM_ICON_CACHE_PROTECTED)
 		return TRUE
 	if(istype(attacking_item, /obj/item/overcapacitor))
 		if(overcap)
@@ -591,7 +591,7 @@
 		user.drop_from_inventory(attacking_item, src)
 		to_chat(user, SPAN_NOTICE("You install \the [attacking_item] into \the [src]."))
 		overcap = attacking_item
-		add_overlay("overcap_attached", TRUE)
+		AddOverlays("overcap_attached", ATOM_ICON_CACHE_PROTECTED)
 		toolspeed *= 2
 		return TRUE
 	if(attacking_item.isscrewdriver())
@@ -619,7 +619,7 @@
 			return TRUE
 		user.put_in_hands(remove_accessory)
 		to_chat(user, SPAN_NOTICE("You remove \the [remove_accessory] into \the [src]."))
-		cut_overlay("[remove_accessory.icon_state]_attached", TRUE)
+		CutOverlays("[remove_accessory.icon_state]_attached", ATOM_ICON_CACHE_PROTECTED)
 		return TRUE
 	return ..()
 
@@ -1005,7 +1005,7 @@
 	. = ..()
 	var/mutable_appearance/handle = mutable_appearance('icons/obj/tools.dmi', "hammer_handle")
 	handle.color = pick(COLOR_BLUE, COLOR_RED, COLOR_PURPLE, COLOR_BROWN, COLOR_GREEN, COLOR_CYAN, COLOR_YELLOW)
-	add_overlay(handle)
+	AddOverlays(handle)
 
 /obj/item/hammer/ishammer()
 	return TRUE

code/game/objects/structures/bonfire.dm

@@ -357,20 +357,20 @@ GLOBAL_LIST_EMPTY(total_active_bonfires)
 	name = "[material.display_name] fireplace"
 
 /obj/structure/bonfire/fireplace/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(on_fire)
 		switch(fuel)
 			if(0 to 250)
-				add_overlay("fireplace_fire0")
+				AddOverlays("fireplace_fire0")
 			if(251 to 750)
-				add_overlay("fireplace_fire1")
+				AddOverlays("fireplace_fire1")
 			if(751 to 1200)
-				add_overlay("fireplace_fire2")
+				AddOverlays("fireplace_fire2")
 			if(1201 to 1700)
-				add_overlay("fireplace_fire3")
+				AddOverlays("fireplace_fire3")
 			if(1700 to 2000)
-				add_overlay("fireplace_fire4")
-		add_overlay("fireplace_glow")
+				AddOverlays("fireplace_fire4")
+		AddOverlays("fireplace_glow")
 
 /obj/structure/bonfire/fireplace/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
 	if(!istype(mover) || mover.checkpass(PASSTABLE))

code/game/objects/structures/coatrack.dm

@@ -58,10 +58,10 @@
 		return ..()
 
 /obj/structure/coatrack/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(coat)
 		if(is_type_in_list(coat, custom_sprites))
-			add_overlay(coat.icon_state)
+			AddOverlays(coat.icon_state)
 		else if(istype(coat, /obj/item/clothing/suit/storage/toggle)) // Using onmob sprites, because they're more consistent than object sprites.
 			var/obj/item/clothing/suit/storage/toggle/T = coat
 			if(!T.opened)
@@ -73,7 +73,7 @@
 			handle_coat_image(T)
 	if(hat)
 		if(is_type_in_list(hat, custom_sprites))
-			add_overlay(hat.icon_state)
+			AddOverlays(hat.icon_state)
 		else if(istype(hat, /obj/item/clothing/head))
 			var/obj/item/clothing/head/H = hat
 			var/matrix/M = matrix()
@@ -82,15 +82,15 @@
 				var/hat_icon_state = "[H.icon_state][WORN_HEAD]" // Needed to bypass contained sprite phoney baloney.
 				hat_image = image(H.icon, hat_icon_state, src.layer, EAST)
 				if(H.build_from_parts)
-					hat_image.add_overlay(overlay_image(H.icon, "[H.icon_state]_[H.worn_overlay]", flags=RESET_COLOR))
+					hat_image.AddOverlays(overlay_image(H.icon, "[H.icon_state]_[H.worn_overlay]", flags=RESET_COLOR))
 			else
 				hat_image = image(INV_HEAD_DEF_ICON, H.icon_state, src.layer, EAST)
 				if(H.build_from_parts)
-					hat_image.add_overlay(overlay_image(icon, "[INV_HEAD_DEF_ICON]_[H.worn_overlay]", flags=RESET_COLOR))
+					hat_image.AddOverlays(overlay_image(icon, "[INV_HEAD_DEF_ICON]_[H.worn_overlay]", flags=RESET_COLOR))
 			M.Turn(90) // Flip the hat over and stick it on the coatrack.
 			M.Translate(-6, 6)
 			hat_image.transform = M
-			add_overlay(hat_image)
+			AddOverlays(hat_image)
 
 /obj/structure/coatrack/proc/handle_coat_image(var/obj/item/clothing/T)
 	var/icon/coat_outline = icon('icons/obj/coatrack.dmi', "outline")
@@ -115,8 +115,8 @@
 		overlay_icon.SwapColor(rgb(255, 0, 220, 255), rgb(0, 0, 0, 0)) // Slice the overlay in half and slap it on the coat.
 		var/image/overlay_image = image(overlay_icon)
 		overlay_image.appearance_flags = RESET_COLOR
-		coat_image.add_overlay(overlay_image)
+		coat_image.AddOverlays(overlay_image)
 
 	M.Translate(-1, 5) // Stick it on the coat rack.
 	coat_image.transform = M
-	add_overlay(coat_image)
+	AddOverlays(coat_image)

code/game/objects/structures/crates_lockers/closets.dm

@@ -546,21 +546,21 @@
 
 /obj/structure/closet/update_icon()
 	if(!door_underlay)
-		cut_overlays()
+		ClearOverlays()
 
 	if(!opened)
 		layer = OBJ_LAYER
 		if(welded)
-			add_overlay("[icon_door_overlay]welded")
+			AddOverlays("[icon_door_overlay]welded")
 		if(!is_animating_door)
 			if(icon_door)
-				add_overlay("[icon_door]_door")
+				AddOverlays("[icon_door]_door")
 				if(double_doors)
-					add_overlay("[icon_door]_door_alt")
+					AddOverlays("[icon_door]_door_alt")
 			if(!icon_door)
-				add_overlay("[icon_state]_door")
+				AddOverlays("[icon_state]_door")
 				if(double_doors)
-					add_overlay("[icon_state]_door_alt")
+					AddOverlays("[icon_state]_door_alt")
 			if(secure)
 				update_secure_overlays()
 		if(secure && secure_lights)
@@ -568,18 +568,18 @@
 	else if(opened)
 		layer = BELOW_OBJ_LAYER
 		if(!is_animating_door)
-			add_overlay("[icon_door_override ? icon_door : icon_state]_open")
+			AddOverlays("[icon_door_override ? icon_door : icon_state]_open")
 		if(secure && secure_lights)
 			update_secure_overlays()
 
 /obj/structure/closet/proc/update_secure_overlays()
 	if(broken)
-		add_overlay("[icon_door_overlay]emag")
+		AddOverlays("[icon_door_overlay]emag")
 	else
 		if(locked)
-			add_overlay("[icon_door_overlay]locked")
+			AddOverlays("[icon_door_overlay]locked")
 		else
-			add_overlay("[icon_door_overlay]unlocked")
+			AddOverlays("[icon_door_overlay]unlocked")
 
 /obj/structure/closet/proc/animate_door(var/closing = FALSE)
 	if(!door_anim_time)
@@ -610,7 +610,7 @@
 	is_animating_door = FALSE // comment this out and the line below to manually tweak the animation end state by fiddling with the door_anim vars to match the open door icon
 	remove_vis_contents(door_obj)
 	update_icon()
-	compile_overlays(src)
+	UpdateOverlays(src)
 
 /obj/structure/closet/proc/animate_door_alt(var/closing = FALSE)
 	if(!door_anim_time)
@@ -641,7 +641,7 @@
 	is_animating_door = FALSE // comment this out and the line below to manually tweak the animation end state by fiddling with the door_anim vars to match the open door icon
 	remove_vis_contents(door_obj_alt)
 	update_icon()
-	compile_overlays(src)
+	UpdateOverlays(src)
 
 /obj/structure/closet/proc/get_door_transform(angle, var/inverse_hinge = FALSE)
 	var/matrix/M = matrix()

code/game/objects/structures/crates_lockers/closets/secure/guncabinet.dm

@@ -24,7 +24,7 @@
 	update_icon()
 
 /obj/structure/closet/secure_closet/guncabinet/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	var/lazors = 0
 	var/shottas = 0
 	for (var/obj/item/gun/G in contents)
@@ -36,10 +36,10 @@
 		for (var/i = 0 to 2)
 			if (lazors > 0 && (shottas <= 0 || prob(50)))
 				lazors--
-				add_overlay("laser[i]")
+				AddOverlays("laser[i]")
 			else if (shottas > 0)
 				shottas--
-				add_overlay("projectile[i]")
+				AddOverlays("projectile[i]")
 	. = ..()
 
 /obj/structure/closet/secure_closet/guncabinet/sci

code/game/objects/structures/crates_lockers/closets/secure/locker.dm

@@ -62,7 +62,7 @@
 	if(!broken)
 		spark(src, 5)
 		desc += " It appears to be broken."
-		add_overlay("[icon_door_overlay]sparking")
+		AddOverlays("[icon_door_overlay]sparking")
 		CUT_OVERLAY_IN("[icon_door_overlay]sparking", 6)
 		playsound(loc, /singleton/sound_category/spark_sound, 60, 1)
 		broken = TRUE

code/game/objects/structures/crates_lockers/closets/statue.dm

@@ -183,7 +183,7 @@
 	dir = L.dir
 	var/image/I
 	I = image(icon = 'icons/obj/statue.dmi', icon_state = "icecube")
-	add_overlay(I)
+	AddOverlays(I)
 
 /obj/structure/closet/statue/ice/shatter(mob/user as mob)
 	if (user)

code/game/objects/structures/crystals.dm

@@ -22,7 +22,7 @@
 	desc = replacetext(desc, "chemical", lowertext(initial(reagent_id.name)))
 	var/mutable_appearance/crystal_overlay = mutable_appearance(icon, "[initial(icon_state)]-overlay")
 	crystal_overlay.color = initial(reagent_id.color)
-	add_overlay(crystal_overlay)
+	AddOverlays(crystal_overlay)
 	if(our_creator)
 		creator = our_creator
 

code/game/objects/structures/extinguisher.dm

@@ -76,16 +76,16 @@
 	update_icon()
 
 /obj/structure/extinguisher_cabinet/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(has_extinguisher)
 		if(istype(has_extinguisher, /obj/item/extinguisher/mini))
-			add_overlay("extinguisher_mini")
+			AddOverlays("extinguisher_mini")
 		else
-			add_overlay("extinguisher_full")
+			AddOverlays("extinguisher_full")
 	if(opened)
-		add_overlay("cabinet_door_open")
+		AddOverlays("cabinet_door_open")
 	else
-		add_overlay("cabinet_door_closed")
+		AddOverlays("cabinet_door_closed")
 
 /obj/structure/extinguisher_cabinet/do_simple_ranged_interaction(var/mob/user)
 	if(has_extinguisher)

code/game/objects/structures/fireaxe_cabinet.dm

@@ -46,19 +46,19 @@
 	update_icon()
 
 /obj/structure/fireaxecabinet/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(fireaxe)
-		add_overlay("axe")
+		AddOverlays("axe")
 	if(shattered)
-		add_overlay("glass4")
+		AddOverlays("glass4")
 	if(unlocked)
-		add_overlay("unlocked")
+		AddOverlays("unlocked")
 	else
-		add_overlay("locked")
+		AddOverlays("locked")
 	if(open)
-		add_overlay("glass_raised")
+		AddOverlays("glass_raised")
 	else
-		add_overlay("glass")
+		AddOverlays("glass")
 
 
 /obj/structure/fireaxecabinet/New()

code/game/objects/structures/hadii_statue.dm

@@ -22,12 +22,12 @@
 		topple()
 
 /obj/structure/hadii_statue/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(toppled)
 		icon_state = "[initial(icon_state)]_toppled"
 		return
 	if(outside)
-		add_overlay("snow")
+		AddOverlays("snow")
 
 /obj/structure/hadii_statue/ex_act(severity)
 	switch(severity)

code/game/objects/structures/janicart.dm

@@ -331,30 +331,30 @@
 	updateUsrDialog()
 
 /obj/structure/janitorialcart/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	has_items = 0
 	if(mybucket)
-		add_overlay("cart_bucket")
+		AddOverlays("cart_bucket")
 		has_items = 1
 		if(mybucket.reagents.total_volume > 0)
-			add_overlay("cart_water")
+			AddOverlays("cart_water")
 	if(mybag)
-		add_overlay("cart_garbage")
+		AddOverlays("cart_garbage")
 		has_items = 1
 	if(mymop)
-		add_overlay("cart_mop")
+		AddOverlays("cart_mop")
 		has_items = 1
 	if(myspray)
-		add_overlay("cart_spray")
+		AddOverlays("cart_spray")
 		has_items = 1
 	if(myreplacer)
 		if (istype(myreplacer, /obj/item/device/lightreplacer/advanced))
-			add_overlay("cart_adv_lightreplacer")
+			AddOverlays("cart_adv_lightreplacer")
 		else
-			add_overlay("cart_replacer")
+			AddOverlays("cart_replacer")
 		has_items = 1
 	if(signs)
-		add_overlay("cart_sign[signs]")
+		AddOverlays("cart_sign[signs]")
 		has_items = 1
 
 //Shamelessly copied from wheelchair code

code/game/objects/structures/kitchen_spike.dm

@@ -31,17 +31,17 @@
 	if(!istype(victim))
 		return
 
-	cut_overlays()
+	ClearOverlays()
 	if(istype(victim, /mob/living/carbon/human))
 		var/mob/living/carbon/human/H = victim
 		if(!issmall(H))
 			return 0
 		meat_type = H.species.meat_type
-		add_overlay(overlay_image(icon, "spikebloody"))
+		AddOverlays(overlay_image(icon, "spikebloody"))
 	else if(istype(victim, /mob/living/carbon/alien))
 		var/mob/living/carbon/alien/A = victim
 		meat_type = A.meat_type
-		add_overlay(overlay_image(icon, "spikebloodygreen"))
+		AddOverlays(overlay_image(icon, "spikebloodygreen"))
 	else
 		return 0
 

code/game/objects/structures/lattice.dm

@@ -155,7 +155,7 @@
 
 /obj/structure/lattice/catwalk/indoor/grate/old/Initialize()
 	. = ..()
-	add_overlay("rust")
+	AddOverlays("rust")
 
 /obj/structure/lattice/catwalk/indoor/grate/damaged
 	icon_state = "grate_dark_dam0"
@@ -173,7 +173,7 @@
 
 /obj/structure/lattice/catwalk/indoor/grate/light/old/Initialize()
 	. = ..()
-	add_overlay("rust")
+	AddOverlays("rust")
 
 /obj/structure/lattice/catwalk/indoor/grate/light/damaged
 	icon_state = "grate_light_dam0"

code/game/objects/structures/light_pole.dm

@@ -66,7 +66,7 @@
 
 /obj/structure/utility_pole/street/on/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	overlays += /obj/effect/overlay/street_light
 	return
 
@@ -82,7 +82,7 @@
 
 /obj/structure/utility_pole/street/classic/on/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	overlays += /obj/effect/overlay/street_light/classic
 	return
 
@@ -99,7 +99,7 @@
 
 /obj/structure/utility_pole/street/crosswalk/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	overlays += /obj/effect/overlay/street_light/crosswalk
 	return
 
@@ -119,13 +119,13 @@
 
 /obj/structure/utility_pole/street/traffic/base/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	overlays += /obj/effect/overlay/street_light/traffic
 	return
 
 /obj/structure/utility_pole/street/traffic/inverted/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	overlays += /obj/effect/overlay/street_light/traffic/inverted
 	return
 

code/game/objects/structures/mop_bucket.dm

@@ -35,9 +35,9 @@
 	update_icon()
 
 /obj/structure/mopbucket/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	if(reagents.total_volume > 0)
-		add_overlay("mopbucket_water")
+		AddOverlays("mopbucket_water")
 
 /obj/structure/mopbucket/on_reagent_change()
 	. = ..()

code/game/objects/structures/plasticflaps.dm

@@ -31,10 +31,10 @@
 	var/image/plasticflaps_overlay = overlay_image(icon, "plasticflaps_overlay", null, RESET_COLOR)
 	if(dir == WEST || dir == EAST)
 		plasticflaps_overlay.pixel_y = -13
-	add_overlay(plasticflaps_overlay)
+	AddOverlays(plasticflaps_overlay)
 
 /obj/structure/plasticflaps/Destroy()
-	cut_overlays()
+	ClearOverlays()
 	if(airtight)
 		clear_airtight()
 	. = ..()

code/game/objects/structures/safe.dm

@@ -97,12 +97,12 @@ FLOOR SAFES
 		else
 			icon_state = initial(icon_state)
 
-	cut_overlay(drill_overlay)
+	CutOverlays(drill_overlay)
 	if(istype(drill, /obj/item/thermal_drill))
 		var/drill_icon = istype(drill, /obj/item/thermal_drill/diamond_drill) ? "d" : "h"
 		var/state = "[initial(icon_state)]_[drill_icon]-drill-[(datum_flags & DF_ISPROCESSING) ? "on" : "off"]"
 		drill_overlay = image(icon = 'icons/effects/drill.dmi', icon_state = state, pixel_x = drill_x_offset, pixel_y = drill_y_offset)
-		add_overlay(drill_overlay)
+		AddOverlays(drill_overlay)
 
 /obj/structure/safe/attack_hand(mob/user as mob)
 	if(drill)

code/game/objects/structures/stool_bed_chair_nest/bed.dm

@@ -78,7 +78,7 @@
 	generate_strings()
 	// Prep icon.
 	icon_state = ""
-	cut_overlays()
+	ClearOverlays()
 	// Base icon.
 
 	generate_overlay_cache(material) //Generate base icon cache
@@ -105,7 +105,7 @@
 			else if(overlay_material.icon_colour) // Either that, or just fall back on the regular material color.
 				I.color = overlay_material.icon_colour
 		furniture_cache[cache_key] = I
-	add_overlay(furniture_cache[cache_key]) // Use image from cache key!
+	AddOverlays(furniture_cache[cache_key]) // Use image from cache key!
 
 /obj/structure/bed/proc/generate_strings()
 	if(material_alteration & MATERIAL_ALTERATION_NAME)
@@ -390,7 +390,7 @@
 	return ..()
 
 /obj/structure/bed/roller/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	vis_contents = list()
 	if(density)
 		if(anchored)
@@ -404,15 +404,15 @@
 		var/percentage = round((beaker.reagents.total_volume / beaker.volume) * 100, 25)
 		var/image/filling = image(icon, "iv_filling[percentage]")
 		filling.color = beaker.reagents.get_color()
-		iv.add_overlay(filling)
+		iv.AddOverlays(filling)
 		if(percentage < 25)
-			iv.add_overlay(image(icon, "light_low"))
+			iv.AddOverlays(image(icon, "light_low"))
 		if(density)
 			iv.pixel_y = 7
-		add_overlay(iv)
+		AddOverlays(iv)
 		if(has_iv_light)
 			var/image/light = image(icon, "iv[iv_attached]_l")
-			add_overlay(light)
+			AddOverlays(light)
 	if(vitals)
 		vitals.update_monitor()
 		add_vis_contents(vitals)

code/game/objects/structures/stool_bed_chair_nest/stools.dm

@@ -243,7 +243,7 @@
 
 /obj/item/material/stool/update_icon()
 	icon_state = "[base_icon]_item"
-	cut_overlays()
+	ClearOverlays()
 	if(padding_material)	// Handles padding overlay and inhand overlays.
 		var/image/padding_overlay = image(icon, "[base_icon]_item_padding")
 		padding_overlay.appearance_flags = RESET_COLOR
@@ -255,7 +255,7 @@
 		else if(padding_material.icon_colour)
 			padding_overlay.color = padding_material.icon_colour
 			worn_overlay_color = padding_material.icon_colour
-		add_overlay(padding_overlay)
+		AddOverlays(padding_overlay)
 	else
 		build_from_parts = FALSE
 	update_held_icon()

code/game/objects/structures/tank_dispenser.dm

@@ -28,17 +28,17 @@
 	update_icon()
 
 /obj/structure/dispenser/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	switch(oxygen_tanks)
 		if(1 to 4)
-			add_overlay("oxygen-[oxygen_tanks]")
+			AddOverlays("oxygen-[oxygen_tanks]")
 		if(5 to INFINITY)
-			add_overlay("oxygen-5")
+			AddOverlays("oxygen-5")
 	switch(phoron_tanks)
 		if(1 to 4)
-			add_overlay("phoron-[phoron_tanks]")
+			AddOverlays("phoron-[phoron_tanks]")
 		if(5 to INFINITY)
-			add_overlay("phoron-5")
+			AddOverlays("phoron-5")
 
 /obj/structure/dispenser/attack_ai(mob/user)
 	if(user.Adjacent(src))

code/game/objects/structures/under_wardrobe.dm

@@ -7,8 +7,8 @@
 
 /obj/structure/undies_wardrobe/Initialize(mapload)
 	. = ..()
-	add_overlay("cabinet_door")
-	add_overlay("cabinet_door_alt")
+	AddOverlays("cabinet_door")
+	AddOverlays("cabinet_door_alt")
 
 /obj/structure/undies_wardrobe/attack_hand(var/mob/user)
 	if(!human_who_can_use_underwear(user))

code/game/objects/structures/urban.dm

@@ -9,7 +9,7 @@
 
 /obj/structure/automobile/random/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	name = "[pick("deluxe Shibata Sport automotive","beat-up Poplar Auto Group automotive","weathered Shibata Sport automotive","beat-up Langenfeld automotive","deluxe Langenfeld automotive","weathered Langenfeld automotive")]"
 	desc = "A [name] vehicle of working condition."
 	icon_state = "car[rand(1, 10)]"
@@ -449,7 +449,7 @@
 
 /obj/structure/sign/billboard/advert/random/Initialize(mapload)
 	. = ..()
-	cut_overlays()
+	ClearOverlays()
 	icon_state = "sign[rand(1, 14)]"
 	return
 

code/game/objects/structures/vr/_remote_chair.dm

@@ -47,7 +47,7 @@
 		if(H.old_mob)
 			to_chat(H, SPAN_WARNING("The chair rejects you! You cannot recursively control bodies."))
 			return
-	add_overlay(image('icons/obj/furniture.dmi', src, "vr_helmet", FLY_LAYER))
+	AddOverlays(image('icons/obj/furniture.dmi', src, "vr_helmet", FLY_LAYER))
 	START_PROCESSING(SSprocessing, src)
 
 
@@ -64,6 +64,6 @@
 		var/mob/M = buckled
 		if(istype(M) && M.vr_mob)
 			M.vr_mob.body_return()
-		cut_overlays()
+		ClearOverlays()
 		STOP_PROCESSING(SSprocessing, src)
 	..()

code/game/objects/structures/watercloset.dm

@@ -185,13 +185,13 @@
 			add_fingerprint(user)
 
 /obj/machinery/shower/update_icon()	//this is terribly unreadable, but basically it makes the shower mist up
-	cut_overlays()					//once it's been on for a while, in addition to handling the water overlay.
+	ClearOverlays()					//once it's been on for a while, in addition to handling the water overlay.
 	if(mymist)
 		qdel(mymist)
 
 	if(on)
 		soundloop.start(src)
-		add_overlay(image('icons/obj/watercloset.dmi', src, "water", MOB_LAYER + 1, dir))
+		AddOverlays(image('icons/obj/watercloset.dmi', src, "water", MOB_LAYER + 1, dir))
 		if(temperature_settings[watertemp] < T20C)
 			return //no mist for cold water
 		if(!ismist)

code/game/objects/structures/window.dm

@@ -104,12 +104,12 @@
 		updateSilicate()
 
 /obj/structure/window/proc/updateSilicate()
-	cut_overlays()
+	ClearOverlays()
 
 	var/image/img = image(icon, icon_state)
 	img.color = "#ffffff"
 	img.alpha = silicate * 255 / 100
-	add_overlay(img)
+	AddOverlays(img)
 
 /obj/structure/window/proc/shatter(var/display_message = 1)
 	playsound(src, /singleton/sound_category/glass_break_sound, 70, 1)