Player Z-tracking, again

code/game/atoms_movable.dm

@@ -254,6 +254,12 @@
 		loc = destination
 
 		if(!same_loc)
+			var/turf/oldturf = get_turf(oldloc)
+			var/turf/destturf = get_turf(destination)
+			var/old_z = (oldturf ? oldturf.z : null)
+			var/dest_z = (destturf ? destturf.z : null)
+			if (old_z != dest_z)
+				onTransitZ(old_z, dest_z)
 			destination.Entered(src, oldloc)
 			if(destarea && old_area != destarea)
 				destarea.Entered(src, oldloc)
@@ -276,6 +282,11 @@
 				old_area.Exited(src, null)
 		loc = null
 
+/atom/movable/proc/onTransitZ(old_z,new_z)
+	for (var/item in src) // Notify contents of Z-transition. This can be overridden IF we know the items contents do not care.
+		var/atom/movable/AM = item
+		AM.onTransitZ(old_z,new_z)
+
 //Called whenever an object moves and by mobs when they attempt to move themselves through space
 //And when an object or action applies a force on src, see newtonian_move() below
 //Return 0 to have src start/keep drifting in a no-grav area and 1 to stop/not start drifting

code/game/machinery/vending.dm

@@ -1190,6 +1190,9 @@ IF YOU MODIFY THE PRODUCTS LIST OF A MACHINE, MAKE SURE TO UPDATE ITS RESUPPLY C
 	refill_canister = /obj/item/vending_refill/games
 
 
+/obj/machinery/vending/onTransitZ()
+	return
+
 #undef STANDARD_CHARGE
 #undef CONTRABAND_CHARGE
 #undef COIN_CHARGE

code/game/turfs/space/space.dm

@@ -130,9 +130,12 @@
 		return
 
 	if(destination_z)
+		var/old_z = A.z
 		A.x = destination_x
 		A.y = destination_y
 		A.z = destination_z
+		if (old_z != destination_z)
+			A.onTransitZ(old_z, destination_z)
 
 		if(isliving(A))
 			var/mob/living/L = A