changes

code/game/area/areas.dm

@@ -26,6 +26,8 @@
 	var/clockwork_warp_fail = "The structure there is too dense for warping to pierce. (This is normal in high-security areas.)"
 	/// Persistent debris alowed
 	var/persistent_debris_allowed = TRUE
+	/// Dirty flooring allowed
+	var/dirt_buildup_allowed = TRUE
 
 	/// If mining tunnel generation is allowed in this area
 	var/tunnel_allowed = FALSE

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

@@ -57,10 +57,28 @@
 	name = "dirt"
 	desc = "Someone should clean that up."
 	icon_state = "dirt"
+	alpha = 127
 	canSmoothWith = list(/obj/effect/decal/cleanable/dirt, /turf/closed/wall, /obj/structure/falsewall)
 	smooth = SMOOTH_FALSE
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	beauty = -75
+	mergeable_decal = TRUE
+	persistent = TRUE
+
+/obj/effect/decal/cleanable/dirt/proc/dirty(strength)
+	if(alpha < 255)
+		alpha += strength
+		if(alpha > 255)
+			alpha = 255
+
+/obj/effect/decal/cleanable/dirt/PersistenceSave(list/data)
+	. = ..()
+	data["alpha"] = alpha
+
+/obj/effect/decal/cleanable/dirt/PersistenceLoad(list/data)
+	. = ..()
+	if(data["alpha"])
+		alpha = data["alpha"]
 
 /obj/effect/decal/cleanable/dirt/Initialize()
 	. = ..()

code/game/turfs/open.dm

@@ -1,5 +1,12 @@
 /turf/open
 	plane = FLOOR_PLANE
+	/// Does dirt buildup happen on us?
+	var/dirt_buildup_allowed = FALSE
+	/// Dirt level.
+	var/dirtyness = 0
+	/// Dirt level to spawn dirt.
+	var/dirt_spawn_threshold = 100
+	/// Slowdown applied to mobs on us.
 	var/slowdown = 0 //negative for faster, positive for slower
 
 	var/postdig_icon_change = FALSE

code/game/turfs/simulated/chasm.dm

@@ -9,6 +9,7 @@
 	canSmoothWith = list(/turf/open/floor/fakepit, /turf/open/chasm)
 	density = TRUE //This will prevent hostile mobs from pathing into chasms, while the canpass override will still let it function like an open turf
 	bullet_bounce_sound = null //abandon all hope ye who enter
+	dirt_buildup_allowed = FALSE
 
 /turf/open/chasm/Initialize()
 	. = ..()

code/game/turfs/simulated/dirtystation.dm

@@ -8,6 +8,9 @@
 //Making the station dirty, one tile at a time. Called by master controller's setup_objects
 
 /turf/open/floor/proc/MakeDirty()
+	if(CONFIG_GET(flag/persistent_debris_only))
+		return
+
 	if(prob(66))	//fastest possible exit 2/3 of the time
 		return
 
@@ -38,7 +41,7 @@
 		return
 
 		//Construction zones. Blood, sweat, and oil.  Oh, and dirt.
-	var/static/list/engine_dirt_areas = typecacheof(list(/area/engine,			
+	var/static/list/engine_dirt_areas = typecacheof(list(/area/engine,
 														/area/crew_quarters/heads/chief,
 														/area/ruin/space/derelict/assembly_line,
 														/area/science/robotics,

code/game/turfs/simulated/floor.dm

@@ -5,6 +5,7 @@
 	name = "floor"
 	icon = 'icons/turf/floors.dmi'
 	baseturfs = /turf/open/floor/plating
+	dirt_buildup_allowed = TRUE
 
 	footstep = FOOTSTEP_FLOOR
 	barefootstep = FOOTSTEP_HARD_BAREFOOT

code/game/turfs/simulated/lava.dm

@@ -6,6 +6,7 @@
 	gender = PLURAL //"That's some lava."
 	baseturfs = /turf/open/lava //lava all the way down
 	slowdown = 2
+	dirt_buildup_allowed = FALSE
 
 	light_range = 2
 	light_power = 0.75

code/game/turfs/simulated/reebe_void.dm

@@ -6,6 +6,7 @@
 	planetary_atmos = TRUE
 	bullet_bounce_sound = null //forever falling
 	tiled_dirt = FALSE
+	dirt_buildup_allowed = FALSE
 
 /turf/open/indestructible/reebe_void/Initialize(mapload)
 	. = ..()

code/game/turfs/space/space.dm

@@ -3,6 +3,7 @@
 	icon_state = "0"
 	name = "\proper space"
 	intact = 0
+	dirt_buildup_allowed = FALSE
 
 	temperature = TCMB
 	thermal_conductivity = OPEN_HEAT_TRANSFER_COEFFICIENT

code/modules/mob/living/living_defines.dm

@@ -63,6 +63,8 @@
 	//Allows mobs to move through dense areas without restriction. For instance, in space or out of holder objects.
 	var/incorporeal_move = FALSE //FALSE is off, INCORPOREAL_MOVE_BASIC is normal, INCORPOREAL_MOVE_SHADOW is for ninjas
 								 //and INCORPOREAL_MOVE_JAUNT is blocked by holy water/salt
+	/// Do we make floors dirty as we move?
+	var/causes_dirt_buildup_on_floor = TRUE
 
 	var/list/roundstart_quirks = list()
 

code/modules/mob/living/living_movement.dm

@@ -101,7 +101,28 @@
 
 	if(lying && !buckled && prob(getBruteLoss()*200/maxHealth))
 		makeTrail(newloc, T, old_direction)
+	if(causes_dirt_buildup_on_floor && (movement_type & GROUND))
+		dirt_buildup()
 
+/**
+ * Attempts to make the floor dirty.
+ */
+/mob/living/proc/dirt_buildup(strength)
+	var/turf/T = loc
+	if(!istype(T) || !T.allow_dirt_buildup)
+		return
+	var/area/A = T.loc
+	if(!A.allow_dirt_buildup)
+		return
+	var/obj/effect/decal/cleanable/dirt/D = locate() in T
+	if(D)
+		D.dirty(strength)
+	else
+		T.dirtyness += strength
+		if(T.dirtyness >= T.dirt_spawn_threshold)
+			D = new /obj/effect/decal/cleanable/dirt(T)
+			D.dirty(T.dirt_spawn_threshold - T.dirtyness)
+			T.dirtyness = 0		// reset.
 
 /mob/living/Move_Pulled(atom/A)
 	. = ..()