Default/mapgen: Clean up ore registrations

Re-order registrations
Add and improve comments
Change sand blob ymax to 0 as sand does not always rise above 0
Remove dirt blobs from sandstone as it is unsuitable for
many sandstone biomes and ugly in stony sandstone desert
Change ymax of first iron region to 0

mods/default/mapgen.lua

@@ -42,12 +42,12 @@ minetest.register_alias("mapgen_stair_sandstonebrick", "stairs:stair_sandstonebr
 -- Register ores
 --
 
--- All mapgens except singlenode
--- Blob ore first to avoid other ores inside blobs
-
 function default.register_ores()
+	-- Blob ores
+	-- These first to avoid other ores in blobs
 
 	-- Clay
+	-- This first to avoid clay in sand blobs
 
 	minetest.register_ore({ 
 		ore_type        = "blob",
@@ -78,7 +78,7 @@ function default.register_ores()
 		clust_scarcity  = 16 * 16 * 16,
 		clust_size      = 5,
 		y_min           = -31,
-		y_max           = 4,
+		y_max           = 0,
 		noise_threshold = 0.0,
 		noise_params    = {
 			offset = 0.5,
@@ -95,7 +95,7 @@ function default.register_ores()
 	minetest.register_ore({
 		ore_type        = "blob",
 		ore             = "default:dirt",
-		wherein         = {"default:stone", "default:sandstone"},
+		wherein         = {"default:stone"},
 		clust_scarcity  = 16 * 16 * 16,
 		clust_size      = 5,
 		y_min           = -31,
@@ -132,6 +132,8 @@ function default.register_ores()
 		},
 	})
 
+	-- Scatter ores
+
 	-- Coal
 
 	minetest.register_ore({
@@ -166,7 +168,7 @@ function default.register_ores()
 		clust_num_ores = 3,
 		clust_size     = 2,
 		y_min          = -15,
-		y_max          = 2,
+		y_max          = 0,
 	})
 
 	minetest.register_ore({
@@ -202,39 +204,28 @@ function default.register_ores()
 		y_max          = -64,
 	})
 
-	--Mese
+	-- Copper
 
 	minetest.register_ore({
 		ore_type       = "scatter",
-		ore            = "default:stone_with_mese",
+		ore            = "default:stone_with_copper",
 		wherein        = "default:stone",
-		clust_scarcity = 18 * 18 * 18,
+		clust_scarcity = 12 * 12 * 12,
-		clust_num_ores = 3,
+		clust_num_ores = 4,
-		clust_size     = 2,
+		clust_size     = 3,
-		y_min          = -255,
+		y_min          = -63,
-		y_max          = -64,
+		y_max          = -16,
 	})
 
 	minetest.register_ore({
 		ore_type       = "scatter",
-		ore            = "default:stone_with_mese",
+		ore            = "default:stone_with_copper",
 		wherein        = "default:stone",
-		clust_scarcity = 14 * 14 * 14,
+		clust_scarcity = 9 * 9 * 9,
 		clust_num_ores = 5,
 		clust_size     = 3,
 		y_min          = -31000,
-		y_max          = -256,
+		y_max          = -64,
-	})
-
-	minetest.register_ore({
-		ore_type       = "scatter",
-		ore            = "default:mese",
-		wherein        = "default:stone",
-		clust_scarcity = 36 * 36 * 36,
-		clust_num_ores = 3,
-		clust_size     = 2,
-		y_min          = -31000,
-		y_max          = -1024,
 	})
 
 	-- Gold
@@ -261,6 +252,30 @@ function default.register_ores()
 		y_max          = -256,
 	})
 
+	-- Mese crystal
+
+	minetest.register_ore({
+		ore_type       = "scatter",
+		ore            = "default:stone_with_mese",
+		wherein        = "default:stone",
+		clust_scarcity = 18 * 18 * 18,
+		clust_num_ores = 3,
+		clust_size     = 2,
+		y_min          = -255,
+		y_max          = -64,
+	})
+
+	minetest.register_ore({
+		ore_type       = "scatter",
+		ore            = "default:stone_with_mese",
+		wherein        = "default:stone",
+		clust_scarcity = 14 * 14 * 14,
+		clust_num_ores = 5,
+		clust_size     = 3,
+		y_min          = -31000,
+		y_max          = -256,
+	})
+
 	-- Diamond
 
 	minetest.register_ore({
@@ -285,28 +300,17 @@ function default.register_ores()
 		y_max          = -256,
 	})
 
-	-- Copper
+	-- Mese block
 
 	minetest.register_ore({
 		ore_type       = "scatter",
-		ore            = "default:stone_with_copper",
+		ore            = "default:mese",
 		wherein        = "default:stone",
-		clust_scarcity = 12 * 12 * 12,
+		clust_scarcity = 36 * 36 * 36,
-		clust_num_ores = 4,
+		clust_num_ores = 3,
-		clust_size     = 3,
+		clust_size     = 2,
-		y_min          = -63,
-		y_max          = -16,
-	})
-
-	minetest.register_ore({
-		ore_type       = "scatter",
-		ore            = "default:stone_with_copper",
-		wherein        = "default:stone",
-		clust_scarcity = 9 * 9 * 9,
-		clust_num_ores = 5,
-		clust_size     = 3,
 		y_min          = -31000,
-		y_max          = -64,
+		y_max          = -1024,
 	})
 end