Add torch wield light (disabled by default)

Thanks to sofar, who wrote this in his fork of BlockMen's
torches mod. Everything is credited to him. (But it's GPLv3+,
not LGPLv2.1+)

mods/default/init.lua

@@ -78,6 +78,10 @@ dofile(envpath .. "leafdecay.lua")
 dofile(envpath .. "no_sneak_glitch.lua")
 dofile(envpath .. "sethome.lua")
 dofile(envpath .. "sounds.lua")
+-- torch wield light (optional)
+if core.is_yes(core.setting_get("enable_torches_wieldlight") or false) then
+	dofile(envpath .. "torch_wield_light.lua")
+end
 
 
 --

mods/default/lua/environment/torch_wield_light.lua

@@ -0,0 +1,136 @@
+--[[
+mods/default/lua/environment/torch_wield_light.lua
+==================================================
+The code in this file is from sofar's torches mod (licensed under LGPLv2.1+).
+See https://github.com/minetest-mods/torches for details.
+
+Copyright (C) 2016 sofar <sofar@foo-projects.org>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+]]
+
+--
+-- Torch wield light
+--
+
+local torchlight_update_interval = core.setting_get("torches_wieldlight_interval") or 0.25
+
+-- state tables
+local torchlight = {}
+local playerlist = {}
+
+local function wields_torch(player)
+	if not player then
+		return false
+	end
+	local item = player:get_wielded_item()
+	if not item then
+		return false
+	end
+	return item:get_name() == "default:torch"
+end
+
+local function wielded_torch(name)
+	if not torchlight[name] then
+		return false
+	end
+	return true
+end
+
+local function is_torchlight(pos)
+	local node = core.get_node(pos)
+	return node.name == "default:torchlight"
+end
+
+local function remove_torchlight(pos)
+	if is_torchlight(pos) then
+		core.swap_node(pos, {name = "air"})
+	end
+end
+
+local function place_torchlight(pos)
+	local name = core.get_node(pos).name
+	if name == "default:torchlight" then
+		return true
+	end
+	if (core.get_node_light(pos) or 0) > 11 then
+		-- no reason to place torch here, so save a bunch
+		-- of node updates this way
+		return false
+	end
+	if name == "air" then
+		core.swap_node(pos, {name = "default:torchlight"})
+		return true
+	end
+	return false
+end
+
+local function get_torchpos(player)
+	return vector.add({x = 0, y = 1, z = 0}, vector.round(player:getpos()))
+end
+
+core.register_on_joinplayer(function(player)
+	local name = player:get_player_name()
+	playerlist[name] = true
+end)
+
+core.register_on_leaveplayer(function(player)
+	local name = player:get_player_name()
+	-- don't look at wielded() here, it's likely invalid
+	if torchlight[name] then
+		remove_torchlight(torchlight[name])
+		torchlight[name] = nil
+	end
+	playerlist[name] = nil
+end)
+
+core.register_on_shutdown(function()
+	for i, _ in pairs(torchlight) do
+		remove_torchlight(torchlight[i])
+	end
+end)
+
+local function update_torchlight(dtime)
+	for name, _ in pairs(playerlist) do
+		local player = core.get_player_by_name(name)
+		local wielded = wielded_torch(name)
+		local wields = wields_torch(player)
+
+		if not wielded and wields then
+			local torchpos = get_torchpos(player)
+			if place_torchlight(torchpos) then
+				torchlight[name] = vector.new(torchpos)
+			end
+		elseif wielded and not wields then
+			remove_torchlight(torchlight[name])
+			torchlight[name] = nil
+		elseif wielded and wields then
+			local torchpos = get_torchpos(player)
+			if not vector.equals(torchpos, torchlight[name]) or
+					not is_torchlight(torchpos) then
+				if place_torchlight(torchpos) then
+					remove_torchlight(torchlight[name])
+					torchlight[name] = vector.new(torchpos)
+				elseif vector.distance(torchlight[name], torchpos) > 2 then
+					-- player went into some node
+					remove_torchlight(torchlight[name])
+					torchlight[name] = nil
+				end
+			end
+		end
+	end
+	core.after(torchlight_update_interval, update_torchlight)
+end
+
+core.after(torchlight_update_interval, update_torchlight)

mods/default/lua/nodes/torch.lua

@@ -110,6 +110,19 @@ minetest.register_abm({
 	end
 })
 
+-- for torch wield light
+core.register_node("default:torchlight", {
+	drawtype = "airlike",
+	groups = {not_in_creative_inventory = 1},
+	walkable = false,
+	paramtype = "light",
+	sunlight_propagates = true,
+	light_source = 11,
+	pointable = false,
+	buildable_to = true,
+	drops = {},
+})
+
 -- Crafting
 
 core.register_craft({

settingtypes.txt

@@ -37,3 +37,12 @@ enable_item_drop (Drop items of digged nodes) bool true
 
 #   General difficulty of the game (WIP: Not everything is using this setting already!)
 difficulty (General difficulty) enum normal easy,normal,hard
+
+[Beta Features]
+
+#   This lights you up if you hold a torch in your hand.
+#   This will make your server slower.
+enable_torches_wieldlight (Enable torches wield light) bool false
+
+#   This is the interval for updating the wield light of torches.
+torches_wieldlight_interval (Wield light interval) float 2.5