Initial commit.

README.md

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+Wand of Illumination [wand\_of\_illumination]
+===========================================
+Provides a wand that when used lights up an entire room, but only for a moment.
+
+
+![Wand of Illumination Screenshot](screenshot.png "Wand of Illumination")
+
+
+Features
+--------
+
+- On right click, places an array of invisible light nodes around the player, in a sphere with a current radius of 15 nodes, and with a light spacing of four nodes.
+- Scans only through air, and only replaces air nodes.
+- Uses an abm to cause these light nodes to revert back to air nodes after a short amount of time.
+- Uses mana mod if available. Current cost for use is 100 mana.
+- Note that narrow passages, like dungeon corridors, may not light up, if they don't fall on the 4x light spacing grid.
+
+
+
+WIP—Things that still need to be done.
+----------------------------------
+
+- Come up with a crafting recipe.
+- Determine if I should be using an abm or something else.
+- Optimize mana cost.
+- Tune light generated: brightness, spacing, radius, and decay rate.
+- Come up with a better wand texture.
+- Maybe add option to give bigger sphere of light on shift-right-click, at the cost of more mana.
+
+
+Dependencies
+------------
+
+- Currently has no default dependency. *(However, I'll probably have to add default when a crafting recipe is added.)*
+- Optionally depends on Wuzzy's mana mod. *(Thanks to his Mirror of Returning mod, it was easy to figure out how to add mana support.)*
+
+
+Licenses
+--------
+
+Source code
+
+> The MIT License (MIT)
+
+Media (textures)
+
+> Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
+
+Current wand texture based on farming\_tool\_stonehoe.png by BlockMen

init.lua

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+-- Wand of Illumination [wand_of_illumination]
+-- by David G (kestral246@gmail.com)
+-- 2019-12-28
+
+-- Provides a wand that when used lights up an entire room, but only for a moment.
+
+local brightness_value = 9  -- How bright to make lights.
+local MAX_DIST_SQUARED = 15^2  -- Radius of sphere (squared).
+local maxcount = 15000		-- Maximum number of nodes to check.
+local mana_cost = 100
+
+local using_mana = false
+if minetest.get_modpath("mana") ~= nil then
+	using_mana = true
+end
+
+local scanned = {}			-- Set containing scanned nodes, so they don't get scanned multiple times.
+local tocheck = {}			-- Table of nodes to check.
+local tolight = {}			-- Table of nodes that need to be converted to fill lights.
+
+minetest.register_on_joinplayer(function(player)
+	local pname = player:get_player_name()
+	scanned[pname] = {}
+	tocheck[pname] = {}
+	tolight[pname] = {}
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	local pname = player:get_player_name()
+	scanned[pname] = nil
+	tocheck[pname] = nil
+	tolight[pname] = nil
+end)
+
+local mana_check = function(player, cost)
+	local allowed
+	if using_mana then
+		if mana.subtract(player:get_player_name(), cost) then
+			allowed = true
+		else
+			allowed = false
+		end
+	else
+		allowed = true
+	end
+	return allowed
+end
+
+minetest.register_node("wand_of_illumination:light", {
+	description = "Wand of Illumination Light",
+	drawtype = "airlike",
+	walkable = false,
+	paramtype = "light",
+	sunlight_propagates = true,
+	light_source = brightness_value,
+	pointable = false,
+	buildable_to = true,
+	drops = "",
+	groups = {cracky = 3, oddly_breakable_by_hand = 3, fill_hidden = 1, not_in_creative_inventory = 1},
+})
+
+minetest.register_abm({
+	nodenames = {"wand_of_illumination:light"},
+	interval = 2.0,  -- need to tune
+	chance = 10,  -- need to tune
+	action = function(pos, node, active_object_count, active_object_count_wider)
+		minetest.set_node(pos, {name = "air"})
+	end
+})
+
+-- Determine number of elements in table, for summary output.
+local tlength = function(T)
+	local count = 0
+	for _ in pairs(T) do count = count + 1 end
+	return count
+end
+
+local square = function(x)
+	return x * x
+end
+
+-- Scan neighboring nodes, flag for checking if air.
+local scan_node = function(pname, pos, origin, maxdist2)
+	-- Add y to test, so make search pattern a sphere
+	if square(pos.x - origin.x) + square(pos.y - origin.y) + square(pos.z - origin.z) <= maxdist2 then
+		local enc_pos = minetest.hash_node_position(pos)
+		if scanned[pname][enc_pos] ~= true then  -- hasn't been scanned
+			local name = minetest.get_node(pos).name
+			if name == "air" then  -- checkable
+				table.insert(tocheck[pname], enc_pos)  -- add to check list
+			end
+			scanned[pname][enc_pos] = true  -- don't scan again
+		end
+	end
+end
+
+-- To check, scan all neighbors and determine if this node needs to be converted to light.
+local check_node = function(pname, pos, origin, maxdist2)
+	local enc_pos = minetest.hash_node_position(pos)
+	local name = minetest.get_node(pos).name
+	scan_node(pname, vector.add(pos, {x=0,y=0,z=1}), origin, maxdist2)  -- north
+	scan_node(pname, vector.add(pos, {x=1,y=0,z=0}), origin, maxdist2)  -- east
+	scan_node(pname, vector.add(pos, {x=0,y=0,z=-1}), origin, maxdist2)  -- south
+	scan_node(pname, vector.add(pos, {x=-1,y=0,z=0}), origin, maxdist2)  -- west
+	scan_node(pname, vector.add(pos, {x=0,y=-1,z=0}), origin, maxdist2)  -- down
+	scan_node(pname, vector.add(pos, {x=0,y=1,z=0}), origin, maxdist2)  -- up
+	if name == "air" and ((pos.x%4 == 0 and pos.y%8 == 0 and pos.z%4 == 0) or
+			(pos.x%4 == 2 and pos.y%8 == 4 and pos.z%4 == 2)) then
+		table.insert(tolight[pname], enc_pos)
+	end
+end
+
+local use_wand = function(pname, pos)
+	-- Initialize temporary tables for safety.
+	scanned[pname] = {}
+	tocheck[pname] = {}
+	tolight[pname] = {}
+	-- Search starts at wand position.
+	table.insert(tocheck[pname], minetest.hash_node_position(pos))
+	local count = 1
+	while count <= table.getn(tocheck[pname]) and count <= maxcount do
+		check_node(pname, minetest.get_position_from_hash(tocheck[pname][count]),
+			pos, MAX_DIST_SQUARED)  -- fifo
+		count = count + 1
+	end
+	count = count - 1 
+	local toadd = tlength(tolight[pname])
+	-- Print statistics.
+	--minetest.debug("wand_of_illumination: y = "..tostring(pos.y)..", scan = "..
+	--		tostring(tlength(scanned[pname]))..", check = "..tostring(count)..", lights = "..
+	--		tostring(tlength(tolight[pname])))
+	-- Add lights to all locations flagged for lighting.
+	for _,v in ipairs(tolight[pname]) do
+		local fpos = minetest.get_position_from_hash(v)
+		minetest.set_node(fpos, {name="wand_of_illumination:light"})
+	end
+	-- Clear temporary tables, which could be large.
+	scanned[pname] = {}
+	tocheck[pname] = {}
+	tolight[pname] = {}
+end
+
+minetest.register_tool("wand_of_illumination:wand", {
+	description = "Wand of Illumination",
+	inventory_image = "wand_of_illumination.png",
+	stack_max = 1,
+	on_place = function(itemstack, player, pointed_thing)
+		local pname = player:get_player_name()
+		local pos = vector.add(vector.round(player:get_pos()), {x=0,y=1,z=0})  -- position of wand
+		if mana_check(player, mana_cost) then
+			use_wand(pname, pos)
+		end
+	end,
+	on_secondary_use = function(itemstack, player, pointed_thing)
+		local pname = player:get_player_name()
+		local pos = vector.add(vector.round(player:get_pos()), {x=0,y=1,z=0})  -- position of wand
+		if mana_check(player, mana_cost) then
+			use_wand(pname, pos)
+		end
+	end,
+})

mod.conf

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+name = wand_of_illumination
+description = Light up an entire room, but only for a moment.
+optional_depends = mana