Add API to control respawn logic and behavior

game_api.txt

@@ -632,6 +632,34 @@ set a players home position and teleport a player to home position.
  * `name` Player you wish to teleport to their home position
  * return value: false if player cannot be sent home, otherwise true
 
+Spawn API
+---------
+
+The spawn mod takes care of deciding the position of new and respawning players
+in the world and has an API to modify its behavior.
+
+`spawn.get_default_pos()`
+* Gets the default spawn position as decided by a biome-dependent algorithm.
+* This is not influenced by settings like "static_spawnpoint" or "engine_spawn".
+* return value: a vector or `nil` on failure
+
+`spawn.add_suitable_biome(biome)`:
+* Adds a biome to the list of allowed biomes for the above algorithm.
+* `biome`: Name of a registered biome
+
+`spawn.register_on_spawn(func)`:
+* Registers a callback to be called when a player (re-)spawns. This can be used
+  to intercept the normal logic to e.g. respawn a player at his bed.
+* `func`: `function(player, is_new)` with arguments
+  - `player`: ObjectRef
+  - `is_new`: true if the player is joining the server for the first time
+  - return value: true to skip all other spawn logic, false or nil otherwise
+
+When a player (re-)spawns the following order is executed:
+1. All spawn callbacks in order of registration.
+2. If no result, teleport player to `spawn.get_default_pos()`.
+3. If that fails, spawning is left up to engine.
+
 
 Sfinv API
 ---------

mods/beds/functions.lua

@@ -244,10 +244,9 @@ end
 -- Callbacks
 -- Only register respawn callback if respawn enabled
 if enable_respawn then
-	-- respawn player at bed if enabled and valid position is found
+	-- Respawn player at bed if valid position is found
-	minetest.register_on_respawnplayer(function(player)
+	spawn.register_on_spawn(function(player, is_new)
-		local name = player:get_player_name()
+		local pos = beds.spawn[player:get_player_name()]
-		local pos = beds.spawn[name]
 		if pos then
 			player:set_pos(pos)
 			return true

mods/beds/mod.conf

@@ -1,3 +1,3 @@
 name = beds
 description = Minetest Game mod: beds
-depends = default, wool
+depends = default, wool, spawn

mods/spawn/api.lua

@@ -0,0 +1,49 @@
+spawn = {}
+
+-- provide empty default implementations
+
+function spawn.get_default_pos()
+	return nil
+end
+
+function spawn.add_suitable_biome(biome)
+end
+
+-- Callback registration
+
+spawn.registered_on_spawn = {}
+
+function spawn.register_on_spawn(func)
+	table.insert(spawn.registered_on_spawn, func)
+end
+
+-- Logic run on spawn
+
+local use_engine_spawn = minetest.settings:get("static_spawnpoint") or
+		minetest.settings:get_bool("engine_spawn")
+
+local function on_spawn(player, is_new)
+	-- Ask all callbacks first
+	for _, cb in ipairs(spawn.registered_on_spawn) do
+		if cb(player, is_new) then
+			return true
+		end
+	end
+	-- Fall back to default spawn
+	if not use_engine_spawn then
+		local pos = spawn.get_default_pos()
+		if pos then
+			player:set_pos(pos)
+			return true
+		end
+	end
+	return false
+end
+
+minetest.register_on_newplayer(function(player)
+	on_spawn(player, true)
+end)
+
+minetest.register_on_respawnplayer(function(player)
+	return on_spawn(player, false)
+end)

mods/spawn/init.lua

@@ -1,12 +1,12 @@
--- spawn/init.lua
+-- Always load the API
+----------------------
+dofile(minetest.get_modpath(minetest.get_current_modname()) .. "/api.lua")
 
--- Disable by mapgen, setting or if 'static_spawnpoint' is set
+-- Disable biome-search implementation on unsuitable mapgens
---------------------------------------------------------------
+------------------------------------------------------------
 
 local mg_name = minetest.get_mapgen_setting("mg_name")
-if mg_name == "v6" or mg_name == "singlenode" or
+if mg_name == "v6" or mg_name == "singlenode" then
-		minetest.settings:get("static_spawnpoint") or
-		minetest.settings:get_bool("engine_spawn") then
 	return
 end
 
@@ -23,27 +23,32 @@ local checks = 128 * 128
 local pos = {x = 0, y = 8, z = 0}
 
 
--- Table of suitable biomes
+-- Table of suitable biomes and matching API function
 
-local biome_ids = {
+local biome_ids = {}
-	minetest.get_biome_id("taiga"),
+
-	minetest.get_biome_id("coniferous_forest"),
+function spawn.add_suitable_biome(biome)
-	minetest.get_biome_id("deciduous_forest"),
+	local id = minetest.get_biome_id(biome)
-	minetest.get_biome_id("grassland"),
+	assert(id ~= nil)
-	minetest.get_biome_id("savanna"),
+	biome_ids[id] = true
-}
+end
+
+for _, name in ipairs({
+	"taiga", "coniferous_forest", "deciduous_forest", "grassland", "savanna"
+}) do
+	spawn.add_suitable_biome(name)
+end
 
 -- End of parameters
 --------------------
 
-
 -- Direction table
 
 local dirs = {
-	{x = 0, y = 0, z = 1},
+	vector.new(0, 0, 1),
-	{x = -1, y = 0, z = 0},
+	vector.new(-1, 0, 0),
-	{x = 0, y = 0, z = -1},
+	vector.new(0, 0, -1),
-	{x = 1, y = 0, z = 0},
+	vector.new(1, 0, 0),
 }
 
 
@@ -67,8 +72,8 @@ local chunksize = tonumber(minetest.get_mapgen_setting("chunksize"))
 local spawn_limit = math.max(mapgen_limit - (chunksize + 1) * 16, 0)
 
 
---Functions
+-- Functions
------------
+------------
 
 -- Get next position on square search spiral
 
@@ -98,15 +103,11 @@ local function search()
 	for iter = 1, checks do
 		local biome_data = minetest.get_biome_data(pos)
 		-- Sometimes biome_data is nil
-		local biome = biome_data and biome_data.biome
+		if biome_data and biome_ids[biome_data.biome] then
-		for id_ind = 1, #biome_ids do
+			local spawn_y = minetest.get_spawn_level(pos.x, pos.z)
-			local biome_id = biome_ids[id_ind]
+			if spawn_y then
-			if biome == biome_id then
+				spawn_pos = vector.new(pos.x, spawn_y, pos.z)
-				local spawn_y = minetest.get_spawn_level(pos.x, pos.z)
+				return true
-				if spawn_y then
-					spawn_pos = {x = pos.x, y = spawn_y, z = pos.z}
-					return true
-				end
 			end
 		end
 
@@ -121,38 +122,11 @@ local function search()
 end
 
 
--- On new player spawn and player respawn
+function spawn.get_default_pos()
-
+	-- Search for spawn position once per server session
--- Search for spawn position once per server session. If successful, store
--- position and reposition players, otherwise leave them at engine spawn
--- position.
-
-local function on_spawn(player)
 	if not searched then
 		success = search()
 		searched = true
 	end
-	if success then
+	return success and spawn_pos
-		player:set_pos(spawn_pos)
-	end
-	return success
 end
-
-minetest.register_on_newplayer(function(player)
-	on_spawn(player)
-end)
-
-local enable_bed_respawn = minetest.settings:get_bool("enable_bed_respawn")
-if enable_bed_respawn == nil then
-	enable_bed_respawn = true
-end
-
-minetest.register_on_respawnplayer(function(player)
-	-- Avoid respawn conflict with beds mod
-	if beds and enable_bed_respawn and
-			beds.spawn[player:get_player_name()] then
-		return
-	end
-
-	return on_spawn(player)
-end)

mods/spawn/mod.conf

@@ -1,4 +1,3 @@
 name = spawn
 description = Minetest Game mod: spawn
 depends = default
-optional_depends = beds