Finishes seperating ZAS logic from CanPass().

code/modules/blob/blob.dm

@@ -22,10 +22,8 @@
 	update_icon()
 	return ..(loc)
 
-/obj/effect/blob/CanPass(var/atom/movable/mover, vra/turf/target, var/height = 0, var/air_group = 0)
-	if(air_group || height == 0)
-		return 1
-	return 0
+/obj/effect/blob/CanPass(var/atom/movable/mover, vra/turf/target)
+	return FALSE
 
 /obj/effect/blob/ex_act(var/severity)
 	switch(severity)
@@ -207,5 +205,5 @@
 	else
 		icon_state = "blob_damaged"
 
-/obj/effect/blob/shield/CanPass(var/atom/movable/mover, var/turf/target, var/height = 0, var/air_group = 0)
+/obj/effect/blob/shield/CanPass(var/atom/movable/mover, var/turf/target)
 	return !density

code/modules/blob2/blobs/base_blob.dm

@@ -46,30 +46,19 @@ var/list/blobs = list()
 		color = null
 		set_light(0)
 
-/obj/structure/blob/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
-	world << "/obj/structure/blob/CanPass(mover=[mover], target=[target], height=[height], air_group=[air_group]) called on [src]."
-	if(air_group || (height==0))
-		world << "Returned true due to being air group or having height=0"
-		return TRUE
+// Blob tiles are not actually dense so we need Special Code(tm).
+/obj/structure/blob/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover) && mover.checkpass(PASSBLOB))
-		world << "Returned true due to having PASSBLOB."
 		return TRUE
 	else if(istype(mover, /mob/living))
 		var/mob/living/L = mover
 		if(L.faction == "blob")
-			world << "Returned true due to being in blob faction."
 			return TRUE
 	else if(istype(mover, /obj/item/projectile))
 		var/obj/item/projectile/P = mover
-		if(P.firer && P.firer.faction == "blob")
-			world << "Returned true due to being a projectile fired by someone in blob faction."
+		if(istype(P.firer) && P.firer.faction == "blob")
 			return TRUE
-		world << "Returned false due to being a projectile, with firer not in faction."
-		return FALSE
-	else
-		world << "Returned false."
-		return FALSE
-//	return ..()
+	return FALSE
 
 /obj/structure/blob/examine(mob/user)
 	..()
@@ -264,7 +253,7 @@ var/list/blobs = list()
 	if(!P)
 		return
 
-	if(P.firer && P.firer.faction == "blob")
+	if(istype(P.firer) && P.firer.faction == "blob")
 		return
 
 	var/damage = P.get_structure_damage() // So tasers don't hurt the blob.

code/modules/blob2/blobs/shield.dm

@@ -6,6 +6,7 @@
 	desc = "A solid wall of slightly twitching tendrils."
 	max_integrity = 100
 	point_return = 4
+	can_atmos_pass = ATMOS_PASS_NO
 
 /obj/structure/blob/shield/core
 	point_return = 0

code/modules/holodeck/HolodeckObjects.dm

@@ -320,19 +320,18 @@
 		visible_message("<span class='notice'>[user] dunks [W] into the [src]!</span>", 3)
 		return
 
-/obj/structure/holohoop/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
+/obj/structure/holohoop/CanPass(atom/movable/mover, turf/target)
 	if (istype(mover,/obj/item) && mover.throwing)
 		var/obj/item/I = mover
 		if(istype(I, /obj/item/projectile))
-			return
+			return TRUE
 		if(prob(50))
-			I.loc = src.loc
-			visible_message("<span class='notice'>Swish! \the [I] lands in \the [src].</span>", 3)
+			I.forceMove(loc)
+			visible_message(span("notice", "Swish! \the [I] lands in \the [src]."), 3)
 		else
-			visible_message("<span class='warning'>\The [I] bounces off of \the [src]'s rim!</span>", 3)
-		return 0
-	else
-		return ..(mover, target, height, air_group)
+			visible_message(span("warning", "\The [I] bounces off of \the [src]'s rim!"), 3)
+		return FALSE
+	return ..()
 
 
 /obj/machinery/readybutton

code/modules/hydroponics/trays/tray.dm

@@ -217,13 +217,10 @@
 
 	..()
 
-/obj/machinery/portable_atmospherics/hydroponics/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
-	if(air_group || (height==0)) return 1
-
+/obj/machinery/portable_atmospherics/hydroponics/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover) && mover.checkpass(PASSTABLE))
-		return 1
-	else
-		return 0
+		return TRUE
+	return FALSE
 
 /obj/machinery/portable_atmospherics/hydroponics/proc/check_health()
 	if(seed && !dead && health <= 0)

code/modules/mob/dead/observer/observer.dm

@@ -143,8 +143,8 @@
 		var/mob/observer/dead/M = src
 		M.manifest(user)
 
-/mob/observer/dead/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
-	return 1
+/mob/observer/dead/CanPass(atom/movable/mover, turf/target)
+	return TRUE
 /*
 Transfer_mind is there to check if mob is being deleted/not going to have a body.
 Works together with spawning an observer, noted above.

code/modules/mob/living/living_movement.dm

@@ -1,4 +1,4 @@
-/mob/CanPass(atom/movable/mover, turf/target, height, air_group)
+/mob/CanPass(atom/movable/mover, turf/target)
 	if(ismob(mover))
 		var/mob/moving_mob = mover
 		if ((other_mobs && moving_mob.other_mobs))
@@ -9,4 +9,4 @@
 	return (!mover.density || !density || lying)
 
 /mob/CanZASPass(turf/T, is_zone)
-	return TRUE
+	return ATMOS_PASS_YES

code/modules/power/antimatter/shielding.dm

@@ -74,9 +74,8 @@ proc/cardinalrange(var/center)
 	return
 
 
-/obj/machinery/am_shielding/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
-	if(air_group || (height==0))	return 1
-	return 0
+/obj/machinery/am_shielding/CanPass(atom/movable/mover, turf/target)
+	return FALSE
 
 
 /obj/machinery/am_shielding/process()

code/modules/power/fusion/fusion_particle_catcher.dm

@@ -37,7 +37,7 @@
 	update_icon()
 	return 0
 
-/obj/effect/fusion_particle_catcher/CanPass(var/atom/movable/mover, var/turf/target, var/height=0, var/air_group=0)
+/obj/effect/fusion_particle_catcher/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover, /obj/effect/accelerated_particle) || istype(mover, /obj/item/projectile/beam))
 		return !density
-	return 1
+	return TRUE

code/modules/power/turbine.dm

@@ -95,10 +95,8 @@
 		stat |= BROKEN
 
 // When anchored, don't let air past us.
-/obj/machinery/compressor/CanPass(atom/movable/mover, turf/target, height=1.5, air_group = 0)
-	if(!height || air_group)
-		return !anchored
-	return !density
+/obj/machinery/compressor/CanZASPass(turf/T, is_zone)
+	return anchored ? ATMOS_PASS_NO : ATMOS_PASS_YES
 
 /obj/machinery/compressor/proc/locate_machinery()
 	if(turbine)

code/modules/recycling/disposal.dm

@@ -467,7 +467,7 @@
 		H.vent_gas(loc)
 		qdel(H)
 
-/obj/machinery/disposal/CanPass(atom/movable/mover, turf/target, height, air_group)
+/obj/machinery/disposal/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover, /obj/item/projectile))
 		return 1
 	if (istype(mover,/obj/item) && mover.throwing)
@@ -483,7 +483,7 @@
 				M.show_message("\The [I] bounces off of \the [src]'s rim!", 3)
 		return 0
 	else
-		return ..(mover, target, height, air_group)
+		return ..(mover, target)
 
 // virtual disposal object
 // travels through pipes in lieu of actual items

code/modules/shieldgen/directional_shield.dm

@@ -53,10 +53,8 @@
 		projector = null
 	return ..()
 
-/obj/effect/directional_shield/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
-	if(air_group || (height==0))
-		return TRUE
-	else if(istype(mover, /obj/item/projectile))
+/obj/effect/directional_shield/CanPass(atom/movable/mover, turf/target)
+	if(istype(mover, /obj/item/projectile))
 		var/obj/item/projectile/P = mover
 		if(istype(P, /obj/item/projectile/test)) // Turrets need to try to kill the shield and so their test bullet needs to penetrate.
 			return TRUE
@@ -64,8 +62,6 @@
 		var/bad_arc = reverse_direction(dir) // Arc of directions from which we cannot block.
 		if(check_shield_arc(src, bad_arc, P)) // This is actually for mobs but it will work for our purposes as well.
 			return FALSE
-		else
-			return TRUE
 	return TRUE
 
 /obj/effect/directional_shield/bullet_act(var/obj/item/projectile/P)

code/modules/shieldgen/emergency_shield.dm

@@ -7,6 +7,7 @@
 	opacity = 0
 	anchored = 1
 	unacidable = 1
+	can_atmos_pass = ATMOS_PASS_NO
 	var/const/max_health = 200
 	var/health = max_health //The shield can only take so much beating (prevents perma-prisons)
 	var/shield_generate_power = 7500	//how much power we use when regenerating
@@ -38,10 +39,6 @@
 	update_nearby_tiles()
 	..()
 
-/obj/machinery/shield/CanPass(atom/movable/mover, turf/target, height, air_group)
-	if(!height || air_group) return 0
-	else return ..()
-
 /obj/machinery/shield/attackby(obj/item/weapon/W as obj, mob/user as mob)
 	if(!istype(W)) return
 

code/modules/shieldgen/energy_field.dm

@@ -18,6 +18,7 @@
 	plane = MOB_PLANE
 	layer = ABOVE_MOB_LAYER
 	density = 0
+	can_atmos_pass = ATMOS_PASS_DENSITY
 	var/obj/machinery/shield_gen/my_gen = null
 	var/strength = 0 // in Renwicks
 	var/ticks_recovering = 10
@@ -103,15 +104,6 @@
 		update_icon()
 		update_nearby_tiles()
 
-/obj/effect/energy_field/CanPass(atom/movable/mover, turf/target, height=1.5, air_group = 0)
-	//Purpose: Determines if the object (or airflow) can pass this atom.
-	//Called by: Movement, airflow.
-	//Inputs: The moving atom (optional), target turf, "height" and air group
-	//Outputs: Boolean if can pass.
-
-	//return (!density || !height || air_group)
-	return !density
-
 /obj/effect/energy_field/update_icon(var/update_neightbors = 0)
 	overlays.Cut()
 	var/list/adjacent_shields_dir = list()

code/modules/shieldgen/sheldwallgen.dm

@@ -317,13 +317,9 @@
 	return
 
 
-/obj/machinery/shieldwall/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
-	if(air_group || (height==0)) return 1
-
+/obj/machinery/shieldwall/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover) && mover.checkpass(PASSGLASS))
 		return prob(20)
-	else
-		if (istype(mover, /obj/item/projectile))
-			return prob(10)
-		else
-			return !src.density
+	if(istype(mover, /obj/item/projectile))
+		return prob(10)
+	return !density

code/modules/tables/interactions.dm

@@ -1,21 +1,20 @@
 
-/obj/structure/table/CanPass(atom/movable/mover, turf/target, height, air_group)
-	if(air_group || (height==0)) return 1
+/obj/structure/table/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover,/obj/item/projectile))
 		return (check_cover(mover,target))
 	if (flipped == 1)
 		if (get_dir(loc, target) == dir)
 			return !density
 		else
-			return 1
+			return TRUE
 	if(istype(mover) && mover.checkpass(PASSTABLE))
-		return 1
+		return TRUE
 	if(locate(/obj/structure/table/bench) in get_turf(mover))
-		return 0
+		return FALSE
 	var/obj/structure/table/table = locate(/obj/structure/table) in get_turf(mover)
 	if(table && !table.flipped)
-		return 1
-	return 0
+		return TRUE
+	return FALSE
 
 //checks if projectile 'P' from turf 'from' can hit whatever is behind the table. Returns 1 if it can, 0 if bullet stops.
 /obj/structure/table/proc/check_cover(obj/item/projectile/P, turf/from)