Refactor compass code.

* Split up `get_compass_image()` into smaller functions.  This allows
  for better code sharing between old and new API and globalstep fn.
* Add `get_compass_itemname()` function.  It will be the new API of
  choice, `get_compass_image() will be deprecated soon.
* Remove function declaration out of globalstep function.
* Various other performance improvements.
* Add local aliases for global functions
* Lodestone compasses can only stack 1 item.
* Document functions and variables.
* Fix lodetone compass inaccurately reusing compass descriptions.
* Add usage descriptions to node definitions
* Refactor craftitem registration code.
* Update translation templates.

mods/ITEMS/mcl_compass/init.lua

@@ -1,16 +1,55 @@
-local stereotype_frame = 18
-
-
 local S = minetest.get_translator(minetest.get_current_modname())
 
 mcl_compass = {}
 
+local compass_types = {
+	{
+		name = "compass",
+		desc = S("Compass"),
+		tt = S("Points to the world origin"),
+		longdesc = S("Compasses are tools which point to the world origin (X=0, Z=0) or the spawn point in the Overworld."),
+		usagehelp = S("A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly."),
+	},
+	{
+		name = "compass_lodestone",
+		desc = S("Lodestone Compass"),
+		tt = S("Points to a lodestone"),
+		longdesc = S("Lodestone compasses resemble regular compasses, but they point to a specific lodestone."),
+		usagehelp = S("A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone."),
+	}
+}
+
+-- Number of dynamic compass images (and items registered.)
 local compass_frames = 32
 
+-- The image/item that is craftable and shown in inventories.
+local stereotype_frame = 18
+
+-- random compass spinning tick in seconds.
+-- Increase if there are performance problems.
+local spin_timer_tick = 0.5
+
+-- Local aliases to globals for better lua performance
+local m_deg = math.deg
+local m_atan2 = math.atan2
+local m_floor = math.floor
+local m_rnd = math.random
+local vec_new = vector.new
+local vec_from_str = vector.from_string
+local get_connected_players = minetest.get_connected_players
+local get_item_group = minetest.get_item_group
+local setting_get_pos = minetest.setting_get_pos
+local compass_works = mcl_worlds.compass_works
+local y_to_layer = mcl_worlds.y_to_layer
+
+-- Initialize random compass frame for spinning compass.  It is updated in
+-- the compass globalstep function.
+local random_frame = m_rnd(0, compass_frames-1)
+
 local function get_far_node(pos, itemstack) --code from minetest dev wiki: https://dev.minetest.net/minetest.get_node, some edits have been made to add a cooldown for force loads
 	local node = minetest.get_node(pos)
 	if node.name == "ignore" then
-		tstamp = tonumber(itemstack:get_meta():get_string("last_forceload"))
+		local tstamp = tonumber(itemstack:get_meta():get_string("last_forceload"))
 		if tstamp == nil then --this is only relevant for new lodestone compasses, the ones that have never performes a forceload yet
 			itemstack:get_meta():set_string("last_forceload", tostring(os.time(os.date("!*t"))))
 			tstamp = tonumber(os.time(os.date("!*t")))
@@ -26,154 +65,180 @@ local function get_far_node(pos, itemstack) --code from minetest dev wiki: https
 	return node
 end
 
+--- Get compass needle angle.
+-- Returns the angle that the compass needle should point at expressed in
+-- 360 degrees divided by the number of possible compass image frames..
+--
+-- pos: position of the compass;
+-- target: position that the needle points towards;
+-- dir: rotational direction of the compass.
+--
+local function get_compass_angle(pos, target, dir)
+	local angle_north = m_deg(m_atan2(target.x - pos.x, target.z - pos.z))
+	if angle_north < 0 then angle_north = angle_north + 360 end
+	local angle_dir = -m_deg(dir)
+	local angle_relative = (angle_north - angle_dir + 180) % 360
+	return m_floor((angle_relative/11.25) + 0.5) % compass_frames
+end
 
---Not sure spawn point should be dymanic (is it in mc?)
+--- Get compass image frame.
---local default_spawn_settings = minetest.settings:get("static_spawnpoint")
+-- Returns the compass image frame with the needle direction matching the
-
+-- compass' current position.
--- Timer for random compass spinning
+--
-local random_timer = 0
+-- pos: position of the compass;
-local random_timer_trigger = 0.5 -- random compass spinning tick in seconds. Increase if there are performance problems
+-- dir: rotational direction of the compass.
-
+-- itemstack: the compass including its optional lodestone metadata.
-local random_frame = math.random(0, compass_frames-1)
+--
-
+local function get_compass_frame(pos, dir, itemstack)
-function mcl_compass.get_compass_image(pos, dir, itemstack)
+	local lpos_str = itemstack:get_meta():get_string("pointsto")
-	if not itemstack then
+	if lpos_str == "" then -- normal compass
-		minetest.log("WARNING: mcl_compass.get_compass_image() was called without itemstack, returning random frame!")
+		-- Compasses only work in the overworld
-		return random_frame
+		if compass_works(pos) then
-	end
+			local spawn_pos = setting_get_pos("static_spawnpoint")
-
+				or vec_new(0, 0, 0)
-	local lodestone_pos = minetest.string_to_pos(itemstack:get_meta():get_string("pointsto"))
+			return get_compass_angle(pos, spawn_pos, dir)
-
+		else
-	if lodestone_pos then --lodestone meta present
+			return random_frame
-		local _, dim = mcl_worlds.y_to_layer(lodestone_pos.y)
+		end
-		local _, playerdim = mcl_worlds.y_to_layer(pos.y)
+	else -- lodestone compass
-		
+		local lpos = vec_from_str(lpos_str)
-		if dim == playerdim then --Check if player and compass target are in the same dimension, above check is just if the diemension is valid for the non lodestone compass
+		local _, l_dim = y_to_layer(lpos.y)
-
+		local _, p_dim = y_to_layer(pos.y)
-			if get_far_node(lodestone_pos, itemstack).name == "mcl_compass:lodestone" then --check if lodestone still exists
+		-- compass and lodestone must be in the same dimension
-  				local angle_north = math.deg(math.atan2(lodestone_pos.x - pos.x, lodestone_pos.z - pos.z))
+		if l_dim == p_dim then
-				if angle_north < 0 then angle_north = angle_north + 360 end
+			--check if lodestone still exists
-				local angle_dir = -math.deg(dir)
+			if get_far_node(lpos, itemstack).name == "mcl_compass:lodestone" then
-				local angle_relative = (angle_north - angle_dir + 180) % 360
+				return get_compass_angle(pos, lpos, dir)
-				return math.floor((angle_relative/11.25) + 0.5) % compass_frames .. "_lodestone"
+			else -- lodestone got destroyed
-			else -- lodestone got destroyed
+				return random_frame
-				return random_frame .. "_lodestone"
+			end
-			end		   
-		else
-			return random_frame .. "_lodestone"
-		end
-	else --no lodestone meta, normal compass....
-		local spawn = {x = 0, y=0, z=0} --before you guys tell me that the normal compass no points to real spawn, it always pointed to 0 0
-		local ssp = minetest.setting_get_pos("static_spawnpoint")
-		if ssp then
-			spawn = ssp
-			if type(spawn) ~= "table" or type(spawn.x) ~= "number" or type(spawn.y) ~= "number" or type(spawn.z) ~= "number" then
-				spawn = {x=0,y=0,z=0}
-			end
-		end
-
-		if mcl_worlds.compass_works(pos) then --is the player in the overworld?
-			local angle_north = math.deg(math.atan2(spawn.x - pos.x, spawn.z - pos.z))
-			if angle_north < 0 then angle_north = angle_north + 360 end
-			local angle_dir = -math.deg(dir)
-			local angle_relative = (angle_north - angle_dir + 180) % 360
-			return math.floor((angle_relative/11.25) + 0.5) % compass_frames
 		else
 			return random_frame
 		end
-
 	end
 end
 
-minetest.register_globalstep(function(dtime)
+--- Get partial compass itemname.
-	random_timer = random_timer + dtime
+-- Returns partial itemname of a compass with needle direction matching compass position.
-
+-- Legacy compatibility function for mods using older api.
-	if random_timer >= random_timer_trigger then
+--
-		random_frame = (random_frame + math.random(-1, 1)) % compass_frames
+function mcl_compass.get_compass_image(pos, dir, itemstack)
-		random_timer = 0
+	minetest.log("warning", "mcl_compass: deprecated function " ..
+		"get_compass_image() called, use get_compass_itemname().")
+	local itemstack = ItemStack("mcl_compass:" .. stereotype_frame)
+	local frame = get_compass_frame(pos, dir, itemstack)
+	if itemstack:get_meta():get_string("pointsto") ~= "" then
+		return frame .. "_lodestone"
+	else
+		return frame
 	end
-	for _,player in pairs(minetest.get_connected_players()) do
+end
-		local function has_compass(player)
-			for _,stack in pairs(player:get_inventory():get_list("main")) do
-				if minetest.get_item_group(stack:get_name(), "compass") ~= 0 then
-					return true
-				end
-			end
-			return false
-		end
-		if has_compass(player) then
-			local pos = player:get_pos()
 
-			for j,stack in pairs(player:get_inventory():get_list("main")) do
+--- Get compass itemname.
-				if minetest.get_item_group(stack:get_name(), "compass") ~= 0 then
+-- Returns the itemname of a compass with needle direction matching the
-					local compass_image = mcl_compass.get_compass_image(pos, player:get_look_horizontal(), stack)
+-- current compass position.
-					if minetest.get_item_group(stack:get_name(), "compass")-1 ~= compass_image and minetest.get_item_group(stack:get_name(), "compass")-1 .. "_lodestone" ~=compass_image then --Explaination: First check for normal compasses, secound check for lodestone ones
+--
-						local itemname = "mcl_compass:"..compass_image
+-- pos: position of the compass;
-						--minetest.log(os.time(os.date("!*t")))
+-- dir: rotational orientation of the compass;
-						stack:set_name(itemname)
+-- itemstack: the compass including its optional lodestone metadata.
-						player:get_inventory():set_stack("main", j, stack)
+--
+function mcl_compass.get_compass_itemname(pos, dir, itemstack)
+	if not itemstack then
+		minetest.log("warning", "mcl_compass.get_compass_image called without itemstack!")
+		return "mcl_compass:" .. stereotype_frame
+	end
+	local frame = get_compass_frame(pos, dir, itemstack)
+	if itemstack:get_meta():get_string("pointsto") ~= "" then
+		return "mcl_compass:" .. frame .. "_lodestone"
+	else
+		return "mcl_compass:" .. frame
+	end
+end
+
+-- Timer for randomly spinning compass.
+-- Gets updated and checked in the globalstep function.
+local spin_timer = 0
+
+-- Compass globalstep function.
+-- * updates random spin counter and random frame of spinning compasses;
+-- * updates all compasses in player's inventories to match the correct
+--   needle orientations for their current positions.
+--
+minetest.register_globalstep(function(dtime)
+	spin_timer = spin_timer + dtime
+	if spin_timer >= spin_timer_tick then
+		random_frame = (random_frame + m_rnd(-1, 1)) % compass_frames
+		spin_timer = 0
+	end
+
+	local compass_nr, compass_frame
+	local pos, dir, inv
+	for _, player in pairs(get_connected_players()) do
+		pos = player:get_pos()
+		dir = player:get_look_horizontal()
+		inv = player:get_inventory()
+		for j, stack in pairs(inv:get_list("main")) do
+			compass_nr = get_item_group(stack:get_name(), "compass")
+			if compass_nr ~= 0 then
+				-- check if current compass image still matches true orientation
+				compass_frame = get_compass_frame(pos, dir, stack)
+				if compass_nr - 1 ~= compass_frame then
+					if stack:get_meta():get_string("pointsto") == "" then
+						stack:set_name("mcl_compass:" .. compass_frame)
+					else
+						stack:set_name("mcl_compass:" .. compass_frame .. "_lodestone")
 					end
+					inv:set_stack("main", j, stack)
 				end
-
 			end
 		end
 	end
 end)
 
-local images = {}
+--
-for frame = 0, compass_frames-1 do
+-- Node and craftitem definitions
-	local s = string.format("%02d", frame)
+--
-	table.insert(images, "mcl_compass_compass_"..s..".png")
-end
-
 local doc_mod = minetest.get_modpath("doc")
 
-for i,img in ipairs(images) do
+for _, item in pairs(compass_types) do
-	local inv = 1
+	local name_fmt, img_fmt, stack_max
-	if i == stereotype_frame then
+	if item.name == "compass" then
-		inv = 0
+		name_fmt = "mcl_compass:%d"
+		img_fmt = "mcl_compass_compass_%02d.png"
+		stack_max = 64
+	elseif item.name == "compass_lodestone" then
+		name_fmt = "mcl_compass:%d_lodestone"
+		img_fmt = "mcl_compass_compass_%02d.png^[colorize:purple:50"
+		stack_max = 1
 	end
-	local use_doc, longdesc, tt
+	for i = 0, compass_frames - 1 do
-	--Why is there no usage help? This should be fixed.
+		local def = {
-	--local usagehelp
+			description = item.desc,
-	use_doc = i == stereotype_frame
+			_tt_help = item.tt,
-	if use_doc then
+			inventory_image = string.format(img_fmt, i),
-		tt = S("Points to the world origin")
+			wield_image = string.format(img_fmt, i),
-		longdesc = S("Compasses are tools which point to the world origin (X=0, Z=0) or the spawn point in the Overworld.")
+			stack_max = stack_max,
-	end
+			groups = {compass = i + 1, tool = 1, disable_repair = 1},
-	local itemstring = "mcl_compass:"..(i-1)
+		}
-	minetest.register_craftitem(itemstring, {
+		if i == stereotype_frame then
-		description = S("Compass"),
+			def._doc_items_longdesc = item.longdesc
-		_tt_help = tt,
+			def._doc_items_usagehelp = item.usagehelp
-		_doc_items_create_entry = use_doc,
+		else
-		_doc_items_longdesc = longdesc,
+			def._doc_items_create_entry = false
-		--_doc_items_usagehelp = usagehelp,
+			def.groups.not_in_creative_inventory = 1
-		inventory_image = img,
+		end
-		wield_image = img,
+		local itemstring = string.format(name_fmt, i)
-		stack_max = 64,
+		minetest.register_craftitem(itemstring, table.copy(def))
-		groups = {not_in_creative_inventory=inv, compass=i, tool=1, disable_repair=1 }
-	})
-	
-	minetest.register_craftitem(itemstring .. "_lodestone", {
-		description = S("Lodestone Compass"),
-		_tt_help = tt,
-		_doc_items_create_entry = use_doc,
-		_doc_items_longdesc = longdesc,
-		--_doc_items_usagehelp = usagehelp,
-		inventory_image = img .. "^[colorize:purple:50",
-		wield_image = img .. "^[colorize:purple:50",
-		stack_max = 64,
-		groups = {not_in_creative_inventory=1, compass=i, tool=1, disable_repair=1 }
-	})
 
-	-- Help aliases. Makes sure the lookup tool works correctly
+		-- Help aliases. Makes sure the lookup tool works correctly
-	if not use_doc and doc_mod then
+		if doc_mod and i ~= stereotype_frame then
-		doc.add_entry_alias("craftitems", "mcl_compass:"..(stereotype_frame-1), "craftitems", itemstring)
+			doc.add_entry_alias("craftitems", "mcl_compass:"..(stereotype_frame), "craftitems", itemstring)
+		end
 	end
 end
 
 minetest.register_craft({
-	output = "mcl_compass:"..stereotype_frame,
+	output = "mcl_compass:" .. stereotype_frame,
 	recipe = {
 		{"", "mcl_core:iron_ingot", ""},
 		{"mcl_core:iron_ingot", "mesecons:redstone", "mcl_core:iron_ingot"},
@@ -181,19 +246,10 @@ minetest.register_craft({
 	}
 })
 
-minetest.register_craft({
+minetest.register_alias("mcl_compass:compass", "mcl_compass:" .. stereotype_frame)
-	output = "mcl_compass:lodestone",
-	recipe = {
-		{"mcl_core:stonebrickcarved","mcl_core:stonebrickcarved","mcl_core:stonebrickcarved"},
-		{"mcl_core:stonebrickcarved", "mcl_core:diamondblock", "mcl_core:stonebrickcarved"},
-		{"mcl_core:stonebrickcarved", "mcl_core:stonebrickcarved", "mcl_core:stonebrickcarved"}
-	}
-})
-
-minetest.register_alias("mcl_compass:compass", "mcl_compass:"..stereotype_frame)
 
 -- Export stereotype item for other mods to use
-mcl_compass.stereotype = "mcl_compass:"..tostring(stereotype_frame)
+mcl_compass.stereotype = "mcl_compass:" .. stereotype_frame
 
 
 minetest.register_node("mcl_compass:lodestone",{
@@ -218,3 +274,12 @@ minetest.register_node("mcl_compass:lodestone",{
 	_mcl_blast_resistance = 6,
 	sounds = mcl_sounds.node_sound_stone_defaults()
 })
+
+minetest.register_craft({
+	output = "mcl_compass:lodestone",
+	recipe = {
+		{"mcl_core:stonebrickcarved","mcl_core:stonebrickcarved","mcl_core:stonebrickcarved"},
+		{"mcl_core:stonebrickcarved", "mcl_core:diamondblock", "mcl_core:stonebrickcarved"},
+		{"mcl_core:stonebrickcarved", "mcl_core:stonebrickcarved", "mcl_core:stonebrickcarved"}
+	}
+})

mods/ITEMS/mcl_compass/locale/mcl_compass.de.tr

@@ -1,4 +1,9 @@
 # textdomain: mcl_compass
-Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Kompasse sind Werkzeuge, die zum Ursprungspunkt der Welt (X@=0, Z@=0) oder zum Einstiegspunkt der Welt zeigen.
 Compass=Kompass
 Points to the world origin=Zeigt zum Startpunkt der Welt
+Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Kompasse sind Werkzeuge, die zum Ursprungspunkt der Welt (X@=0, Z@=0) oder zum Einstiegspunkt der Welt zeigen.
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=

mods/ITEMS/mcl_compass/locale/mcl_compass.es.tr

@@ -1,3 +1,9 @@
 # textdomain: mcl_compass
+Compass=Brújula
+Points to the world origin=
 Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Las brújulas son herramientas que apuntan al origen del mundo (X @ = 0, Z @ = 0) o al punto de generación en el mundo.
-Compass=Brújula
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=

mods/ITEMS/mcl_compass/locale/mcl_compass.fr.tr

@@ -1,4 +1,9 @@
 # textdomain: mcl_compass
-Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Les boussoles sont des outils qui pointent vers l'origine du monde (X@=0,Z@=0) ou le point d'apparition dans l'Overworld.
 Compass=Boussole
 Points to the world origin=Pointe vers l'origine mondiale
+Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Les boussoles sont des outils qui pointent vers l'origine du monde (X@=0,Z@=0) ou le point d'apparition dans l'Overworld.
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=

mods/ITEMS/mcl_compass/locale/mcl_compass.pl.tr

@@ -1,4 +1,9 @@
 # textdomain: mcl_compass
-Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Kompasy to narzędzia które wskazują na punkt początku świata (X@=0, Z@=0) lub na miejsce odrodzenia na Powierzchni.
 Compass=Kompas
 Points to the world origin=Wskazuje na początek świata
+Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Kompasy to narzędzia które wskazują na punkt początku świata (X@=0, Z@=0) lub na miejsce odrodzenia na Powierzchni.
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=

mods/ITEMS/mcl_compass/locale/mcl_compass.ru.tr

@@ -1,4 +1,9 @@
 # textdomain: mcl_compass
-Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Компас - инструмент, показывающий на начало мира (X@=0, Z@=0) или на точку возрождения в Верхнем Мире.
 Compass=Компас
 Points to the world origin=Указывает на начало мира
+Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=Компас - инструмент, показывающий на начало мира (X@=0, Z@=0) или на точку возрождения в Верхнем Мире.
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=

mods/ITEMS/mcl_compass/locale/mcl_compass.zh_TW.tr

@@ -1,4 +1,9 @@
 # textdomain: mcl_compass
-Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=指南針是指向世界原點（X@=0，Z@=0）或主世界的出生點的工具。
 Compass=指南針
 Points to the world origin=指向世界原點
+Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=指南針是指向世界原點（X@=0，Z@=0）或主世界的出生點的工具。
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=

mods/ITEMS/mcl_compass/locale/template.txt

@@ -1,4 +1,9 @@
 # textdomain: mcl_compass
-Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=
 Compass=
 Points to the world origin=
+Compasses are tools which point to the world origin (X@=0, Z@=0) or the spawn point in the Overworld.=
+A Compass always points to the world spawn point when the player is in the overworld.  In other dimensions, it spins randomly.=
+Lodestone Compass=
+Points to a lodestone=
+Lodestone compasses resemble regular compasses, but they point to a specific lodestone.=
+A Lodestone compass can be made from an ordinary compass by using it on a lodestone.  After becoming a lodestone compass, it always points to its linked lodestone, provided that they are in the same dimension.  If not in the same dimension, the lodestone compass spins randomly, similarly to a regular compass when outside the overworld.  A lodestone compass can be relinked with another lodestone.=