Give subgames the ability to disallow specific mapgens (minetest#6792)

builtin/common/misc_helpers.lua

@@ -551,7 +551,7 @@ end
 --------------------------------------------------------------------------------
 if INIT == "mainmenu" then
 	function core.get_game(index)
-		local games = game.get_games()
+		local games = core.get_games()
 
 		if index > 0 and index <= #games then
 			return games[index]

builtin/mainmenu/dlg_create_world.lua

@@ -15,11 +15,39 @@
 --with this program; if not, write to the Free Software Foundation, Inc.,
 --51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+local worldname = ""
+
 local function create_world_formspec(dialogdata)
 	local mapgens = core.get_mapgen_names()
 
 	local current_seed = core.settings:get("fixed_map_seed") or ""
 	local current_mg   = core.settings:get("mg_name")
+	local gameid = core.settings:get("menu_last_game")
+
+	local game, gameidx = nil , 0
+	if gameid ~= nil then
+		game, gameidx = gamemgr.find_by_gameid(gameid)
+
+		if gameidx == nil then
+			gameidx = 0
+		end
+	end
+
+	local gamepath = core.get_game(gameidx).path
+	local gameconfig = Settings(gamepath.."/game.conf")
+
+	local disallowed_mapgens = (gameconfig:get("disallowed_mapgens") or ""):split()
+	for key, value in pairs(disallowed_mapgens) do
+		disallowed_mapgens[key] = value:trim()
+	end
+
+	if disallowed_mapgens then
+		for i = #mapgens, 1, -1 do
+			if table.indexof(disallowed_mapgens, mapgens[i]) > 0 then
+				table.remove(mapgens, i)
+			end
+		end
+	end
 
 	local mglist = ""
 	local selindex = 1
@@ -32,23 +60,12 @@ local function create_world_formspec(dialogdata)
 		mglist = mglist .. v .. ","
 	end
 	mglist = mglist:sub(1, -2)
-
-	local gameid = core.settings:get("menu_last_game")
-
-	local game, gameidx = nil , 0
-	if gameid ~= nil then
-		game, gameidx = gamemgr.find_by_gameid(gameid)
-
-		if gameidx == nil then
-			gameidx = 0
-		end
-	end
 
 	current_seed = core.formspec_escape(current_seed)
 	local retval =
 		"size[11.5,6.5,true]" ..
 		"label[2,0;" .. fgettext("World name") .. "]"..
-		"field[4.5,0.4;6,0.5;te_world_name;;]" ..
+		"field[4.5,0.4;6,0.5;te_world_name;;" .. minetest.formspec_escape(worldname) .. "]" ..
 
 		"label[2,1;" .. fgettext("Seed") .. "]"..
 		"field[4.5,1.4;6,0.5;te_seed;;".. current_seed .. "]" ..
@@ -121,10 +138,14 @@ local function create_world_buttonhandler(this, fields)
 		return true
 	end
 
+	worldname = fields.te_world_name
+
 	if fields["games"] then
+		local gameindex = core.get_textlist_index("games")
+		core.settings:set("menu_last_game", gamemgr.games[gameindex].id)
 		return true
 	end
-	
+
 	if fields["world_create_cancel"] then
 		this:delete()
 		return true
@@ -135,6 +156,7 @@ end
 
 
 function create_create_world_dlg(update_worldlistfilter)
+	worldname = ""
 	local retval = dialog_create("sp_create_world",
 					create_world_formspec,
 					create_world_buttonhandler,

doc/lua_api.txt

@@ -53,14 +53,24 @@ Games are looked up from:
 
 where `gameid` is unique to each game.
 
-The game directory contains the file `game.conf`, which contains these fields:
+The game directory contains the file `game.conf`, which contains:
 
     name = <Human-readable full name of the game>
 
 e.g.
 
     name = Minetest
 
+Optionally, game.conf can also contain:
+
+    disallowed_mapgens = <comma-separated mapgens>
+
+e.g.
+
+    disallowed_mapgens = v5,v6,flat
+
+These mapgens are removed from the list of mapgens for the game.
+
 The game directory can contain the file minetest.conf, which will be used
 to set default settings when running the particular game.
 It can also contain a settingtypes.txt in the same format as the one in builtin.