Complex concrete dungeon materials

Use all base concrete materials in dungeon gen.

- From y=+32 to y=+64, transition from stone to a 50/50 mix
  of adobe and sandstone.
- From y=-640 to y=-768, transition from stone to tarstone.

Adds some more variety and reason to explore dungeons.

mods/nc_concrete/dungeon.lua

@@ -0,0 +1,39 @@
+-- LUALOCALS < ---------------------------------------------------------
+local minetest, nodecore
+    = minetest, nodecore
+-- LUALOCALS > ---------------------------------------------------------
+
+local modname = minetest.get_current_modname()
+
+local function profile(name)
+	return {
+		fill = modname .. ":" .. name,
+		brick = "nc_stonework:bricks_" .. name,
+		bonded = "nc_stonework:bricks_" .. name .. "_bonded",
+	}
+end
+
+local dirty = profile("adobe")
+local sandy = profile("sandstone")
+local tarry = profile("coalstone")
+
+local heightperlin
+local surfperlin
+minetest.after(0, function()
+		heightperlin = minetest.get_perlin(4367, 3, 0.5, 8)
+		surfperlin = minetest.get_perlin(865, 3, 0.5, 64)
+	end)
+
+local oldbricks = nodecore.dungeon_bricks
+function nodecore.dungeon_bricks(pos, rng)
+	if pos.y >= 32 then
+		if pos.y >= 64 or heightperlin:get_3d(pos) < (pos.y / 16 - 3) then
+			return surfperlin:get_3d(pos) > 0 and dirty or sandy
+		end
+		return oldbricks(pos, rng)
+	end
+	if pos.y >= -640 then return oldbricks(pos, rng) end
+	if pos.y < -768 then return tarry end
+	if heightperlin:get_3d(pos) > (pos.y / 64 + 11) then return tarry end
+	return oldbricks(pos, rng)
+end

mods/nc_concrete/init.lua

@@ -11,4 +11,5 @@ include("patterns")
 include("node")
 include("register")
 include("stylus")
+include("dungeon")
 include("hints")