Multi-Z.

code/modules/multiz/basic.dm

@@ -0,0 +1,31 @@
+// If you add a more comprehensive system, just untick this file.
+// WARNING: Only works for up to 17 z-levels!
+var/z_levels = 0 // Each bit represents a connection between adjacent levels.  So the first bit means levels 1 and 2 are connected.
+
+// If the height is more than 1, we mark all contained levels as connected.
+/obj/effect/landmark/map_data/New()
+	for(var/i = z - 1 to height - 2)
+		z_levels |= 1 << i
+	del src
+
+HasAbove(z)
+	if(z > world.maxz || z > 17 || z < 2)
+		return 0
+	return z_levels & (1 << (z - 1))
+
+HasBelow(z)
+	if(z >= world.maxz || z > 16 || z < 1)
+		return 0
+	return z_levels & (1 << z)
+
+GetAbove(var/atom/thing)
+	var/turf/turf = get_turf(thing)
+	if(!istype(turf))
+		return null
+	return HasBelow(turf.z) ? locate(turf.z, turf.y, turf.z - 1) : null
+
+GetBelow(var/atom/thing)
+	var/turf/turf = get_turf(thing)
+	if(!istype(turf))
+		return null
+	return HasBelow(turf.z) ? locate(turf.z, turf.y, turf.z + 1) : null