changes

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

@@ -3,6 +3,8 @@
 	layer = ABOVE_NORMAL_TURF_LAYER
 	/// Is this kind of cleanable decal persistent
 	var/persistent = FALSE
+	/// Can we stack multiple in one tile?
+	var/persistence_allow_stacking = FALSE
 
 	var/list/random_icon_states = null
 	var/blood_state = "" //I'm sorry but cleanable/blood code is ass, and so is blood_DNA
@@ -36,20 +38,20 @@
 	addtimer(CALLBACK(src, /datum.proc/_AddElement, list(/datum/element/beauty, beauty)), 0)
 
 /**
- * Returns a list of data
+ * A data list is passed into this.
+ * This should return null to skip saving, or the type of data to save. Type must be /cleanable.
  */
-/obj/effect/decal/cleanable/proc/PersistenceSave()
-	return null
+/obj/effect/decal/cleanable/proc/PersistenceSave(list/data)
+	return type
 
 /**
- * Laods from a data list.
+ * Loads from a data list.
  */
 /obj/effect/decal/cleanable/proc/PersistenceLoad(list/data)
 	return
 
 /obj/effect/decal/cleanable/proc/replace_decal(obj/effect/decal/cleanable/C) // Returns true if we should give up in favor of the pre-existing decal
-	if(mergeable_decal)
-		qdel(C)
+	return mergeable_decal
 
 /obj/effect/decal/cleanable/attackby(obj/item/W, mob/user, params)
 	if(istype(W, /obj/item/reagent_containers/glass) || istype(W, /obj/item/reagent_containers/food/drinks))

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

@@ -12,6 +12,8 @@
 	icon_state = "ash"
 	mergeable_decal = FALSE
 	beauty = -50
+	persistent = TRUE
+	persistence_allow_stacking = TRUE
 
 /obj/effect/decal/cleanable/ash/Initialize()
 	. = ..()
@@ -38,6 +40,8 @@
 	icon = 'icons/obj/shards.dmi'
 	icon_state = "tiny"
 	beauty = -100
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/glass/Initialize()
 	. = ..()
@@ -94,6 +98,8 @@
 	light_color = LIGHT_COLOR_GREEN
 	icon_state = "greenglow"
 	beauty = -300
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/greenglow/Initialize(mapload)
 	. = ..()
@@ -122,6 +128,8 @@
 	icon_state = "molten"
 	mergeable_decal = FALSE
 	beauty = -150
+	persistent = TRUE
+	persistence_allow_stacking = TRUE
 
 /obj/effect/decal/cleanable/molten_object/large
 	name = "big gooey grey mass"
@@ -136,6 +144,7 @@
 	icon_state = "vomit_1"
 	random_icon_states = list("vomit_1", "vomit_2", "vomit_3", "vomit_4")
 	beauty = -150
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/vomit/on_attack_hand(mob/user, act_intent = user.a_intent, unarmed_attack_flags)
 	if(ishuman(user))
@@ -151,6 +160,10 @@
 			reagents.trans_to(H, reagents.total_volume)
 			qdel(src)
 
+/obj/effect/decal/cleanable/vomit/PersistenceSave(list/data)
+	. = ..()
+	return /obj/effect/decal/cleanable/vomit/old
+
 /obj/effect/decal/cleanable/vomit/old
 	name = "crusty dried vomit"
 	desc = "You try not to look at the chunks, and fail."
@@ -166,12 +179,16 @@
 	icon = 'icons/effects/tomatodecal.dmi'
 	random_icon_states = list("tomato_floor1", "tomato_floor2", "tomato_floor3")
 	beauty = -100
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/plant_smudge
 	name = "plant smudge"
 	gender = NEUTER
 	icon = 'icons/effects/tomatodecal.dmi'
 	random_icon_states = list("smashed_plant")
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/egg_smudge
 	name = "smashed egg"
@@ -179,6 +196,8 @@
 	gender = NEUTER
 	icon = 'icons/effects/tomatodecal.dmi'
 	random_icon_states = list("smashed_egg1", "smashed_egg2", "smashed_egg3")
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/pie_smudge //honk
 	name = "smashed pie"
@@ -186,6 +205,8 @@
 	gender = NEUTER
 	icon = 'icons/effects/tomatodecal.dmi'
 	random_icon_states = list("smashed_pie")
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/chem_pile
 	name = "chemical pile"
@@ -193,6 +214,8 @@
 	gender = NEUTER
 	icon = 'icons/obj/objects.dmi'
 	icon_state = "ash"
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/shreds
 	name = "shreds"
@@ -200,6 +223,8 @@
 	icon_state = "shreds"
 	gender = PLURAL
 	mergeable_decal = FALSE
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/shreds/ex_act(severity, target)
 	if(severity == 1) //so shreds created during an explosion aren't deleted by the explosion.
@@ -222,6 +247,8 @@
 	desc = "The herpes of arts and crafts."
 	icon = 'icons/effects/atmospherics.dmi'
 	gender = NEUTER
+	mergeable_decal = TRUE
+	persistent = TRUE
 
 /obj/effect/decal/cleanable/glitter/pink
 	name = "pink glitter"
@@ -247,3 +274,5 @@
 	icon = 'icons/effects/blood.dmi'
 	icon_state = "xfloor1"
 	random_icon_states = list("xfloor1", "xfloor2", "xfloor3", "xfloor4", "xfloor5", "xfloor6", "xfloor7")
+	mergeable_decal = TRUE
+	persistent = TRUE

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

@@ -5,6 +5,8 @@
 	icon_state = "rune1"
 	plane = ABOVE_WALL_PLANE //makes the graffiti visible over a wall.
 	gender = NEUTER
+	persistent = TRUE
+	persistence_allow_stacking = TRUE
 	mergeable_decal = FALSE
 	var/do_icon_rotate = TRUE
 	var/rotation = 0
@@ -29,3 +31,27 @@
 	if(main)
 		paint_colour = main
 	add_atom_colour(paint_colour, FIXED_COLOUR_PRIORITY)
+
+/obj/effect/decal/cleanable/crayon/PersistenceSave(list/data)
+	. = ..()
+	if(icon != initial(icon))	// no support for alticons yet, awful system anyways
+		return null
+	data["icon_state"] = icon_stsate
+	data["paint_color"] = paint_colour
+	if(do_icon_rotate)
+		data["rotation"] = rotation
+	data["name"] = name
+
+/obj/effect/decal/cleanable/crayon/PersistenceLoad(list/data)
+	. = ..()
+	if(data["name"])
+		name = data["name"]
+	if(do_icon_rotate && data["rotation"])
+		var/matrix/M = matrix()
+		M.turn(data["rotation"])
+		transform = M
+	if(data["paint_color"])
+		paint_colour = data["paint_color"])
+		add_atom_colour(paint_colour, FIXED_COLOUR_PRIORITY)
+	if(data["icon_state"])
+		icon_state = data["icon_state"]