Add experimental setting to disable superflat

mods/CORE/mcl_init/init.lua

@@ -23,13 +23,17 @@ if mg_name ~= "flat" then
 	mcl_vars.mg_bedrock_is_rough = true
 else
 	local ground = minetest.get_mapgen_setting("mgflat_ground_level")
+	ground = tonumber(ground)
 	if not ground then
 		ground = 8
 	end
-	mcl_vars.mg_overworld_min = ground - 3
-	mcl_vars.mg_overworld_max = mcl_vars.mg_overworld_min + minecraft_height_limit
-
 	-- 1 perfectly flat bedrock layer
+	if minetest.get_mapgen_setting("mcl_superflat_classic") == "false" then
+		mcl_vars.mg_overworld_min = -30912
+	else
+		mcl_vars.mg_overworld_min = ground - 3
+	end
+	mcl_vars.mg_overworld_max = mcl_vars.mg_overworld_min + minecraft_height_limit
 	mcl_vars.mg_bedrock_overworld_min = mcl_vars.mg_overworld_min
 	mcl_vars.mg_bedrock_overworld_max = mcl_vars.mg_bedrock_overworld_min
 	mcl_vars.mg_lava = false

mods/MAPGEN/mcl_mapgen_core/init.lua

@@ -883,8 +883,19 @@ if mg_name == "v6" then
 	register_mgv6_decorations()
 end
 if mg_name == "flat" then
+	local classic = minetest.get_mapgen_setting("mcl_superflat_classic")
+	if classic == nil then
+		classic = minetest.settings:get_bool("mcl_superflat_classic")
+		minetest.set_mapgen_setting("mcl_superflat_classic", "true", true)
+	end
+	if classic ~= "false" then
+		-- Enforce superflat-like mapgen: No hills, lakes or caves
 		minetest.set_mapgen_setting("mg_flags", "nocaves,nodungeons,nodecorations,light", true)
 		minetest.set_mapgen_setting("mgflat_spflags", "nolakes,nohills", true)
+	else
+		-- If superflat mode is disabled, mapgen is way more liberal
+		minetest.set_mapgen_setting("mg_flags", "caves,nodungeons,nodecorations,light", true)
+	end
 else
 	minetest.set_mapgen_setting("mg_flags", "caves,nodungeons,decorations,light", true)
 end

settingtypes.txt

@@ -50,3 +50,12 @@ enable_bed_night_skip (Skip night when sleeping) bool true
 # This setting is experimental and may be changed in later versions.
 # Feedback is appreciated.
 craftguide_progressive_mode (EXPERIMENTAL: Enable recipe book progressive mode) bool true
+
+# If enabled, the “flat” map generator generates a “classic” superflat map:
+# Completely flat, 1 layer of grass blocks on top of 2 layers of dirt on
+# top of a final layer of bedrock.
+# Note if this is enabled, the setting “mgflat_flags” is ignored. To
+# customize the “flat” map generator, you must disable this setting.
+# Warning: Disabling this setting is currently EXPERIMENTAL! The generated map
+# may not be that pretty.
+mcl_superflat_classic (Classic superflat map generation) bool true