Organize builtin into subdirectories

4 files changed, 839 insertions, 0 deletions

diff --git a/builtin/common/async_event.lua b/builtin/common/async_event.lua
new file mode 100644
index 000000000..ef4bf4354
--- /dev/null
+++ b/builtin/common/async_event.lua
@@ -0,0 +1,42 @@
+
+local core = engine or minetest
+
+core.async_jobs = {}
+
+local function handle_job(jobid, serialized_retval)
+	local retval = core.deserialize(serialized_retval)
+	assert(type(core.async_jobs[jobid]) == "function")
+	core.async_jobs[jobid](retval)
+	core.async_jobs[jobid] = nil
+end
+
+if engine ~= nil then
+	core.async_event_handler = handle_job
+else
+	minetest.register_globalstep(function(dtime)
+		for i, job in ipairs(core.get_finished_jobs()) do
+			handle_job(job.jobid, job.retval)
+		end
+	end)
+end
+
+function core.handle_async(func, parameter, callback)
+	-- Serialize function
+	local serialized_func = string.dump(func)
+
+	assert(serialized_func ~= nil)
+
+	-- Serialize parameters
+	local serialized_param = core.serialize(parameter)
+
+	if serialized_param == nil then
+		return false
+	end
+
+	local jobid = core.do_async_callback(serialized_func, serialized_param)
+
+	core.async_jobs[jobid] = callback
+
+	return true
+end
+
diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua
new file mode 100644
index 000000000..9c7349726
--- /dev/null
+++ b/builtin/common/misc_helpers.lua
@@ -0,0 +1,428 @@
+-- Minetest: builtin/misc_helpers.lua
+
+--------------------------------------------------------------------------------
+function basic_dump2(o)
+	if type(o) == "number" then
+		return tostring(o)
+	elseif type(o) == "string" then
+		return string.format("%q", o)
+	elseif type(o) == "boolean" then
+		return tostring(o)
+	elseif type(o) == "function" then
+		return "<function>"
+	elseif type(o) == "userdata" then
+		return "<userdata>"
+	elseif type(o) == "nil" then
+		return "nil"
+	else
+		error("cannot dump a " .. type(o))
+		return nil
+	end
+end
+
+--------------------------------------------------------------------------------
+function dump2(o, name, dumped)
+	name = name or "_"
+	dumped = dumped or {}
+	io.write(name, " = ")
+	if type(o) == "number" or type(o) == "string" or type(o) == "boolean"
+			or type(o) == "function" or type(o) == "nil"
+			or type(o) == "userdata" then
+		io.write(basic_dump2(o), "\n")
+	elseif type(o) == "table" then
+		if dumped[o] then
+			io.write(dumped[o], "\n")
+		else
+			dumped[o] = name
+			io.write("{}\n") -- new table
+			for k,v in pairs(o) do
+				local fieldname = string.format("%s[%s]", name, basic_dump2(k))
+				dump2(v, fieldname, dumped)
+			end
+		end
+	else
+		error("cannot dump a " .. type(o))
+		return nil
+	end
+end
+
+--------------------------------------------------------------------------------
+function dump(o, dumped)
+	dumped = dumped or {}
+	if type(o) == "number" then
+		return tostring(o)
+	elseif type(o) == "string" then
+		return string.format("%q", o)
+	elseif type(o) == "table" then
+		if dumped[o] then
+			return "<circular reference>"
+		end
+		dumped[o] = true
+		local t = {}
+		for k,v in pairs(o) do
+			t[#t+1] = "[" .. dump(k, dumped) .. "] = " .. dump(v, dumped)
+		end
+		return "{" .. table.concat(t, ", ") .. "}"
+	elseif type(o) == "boolean" then
+		return tostring(o)
+	elseif type(o) == "function" then
+		return "<function>"
+	elseif type(o) == "userdata" then
+		return "<userdata>"
+	elseif type(o) == "nil" then
+		return "nil"
+	else
+		error("cannot dump a " .. type(o))
+		return nil
+	end
+end
+
+--------------------------------------------------------------------------------
+function string:split(sep)
+	local sep, fields = sep or ",", {}
+	local pattern = string.format("([^%s]+)", sep)
+	self:gsub(pattern, function(c) fields[#fields+1] = c end)
+	return fields
+end
+
+--------------------------------------------------------------------------------
+function file_exists(filename)
+	local f = io.open(filename, "r")
+	if f==nil then
+		return false
+	else
+		f:close()
+		return true
+	end
+end
+
+--------------------------------------------------------------------------------
+function string:trim()
+	return (self:gsub("^%s*(.-)%s*$", "%1"))
+end
+
+assert(string.trim("\n \t\tfoo bar\t ") == "foo bar")
+
+--------------------------------------------------------------------------------
+function math.hypot(x, y)
+	local t
+	x = math.abs(x)
+	y = math.abs(y)
+	t = math.min(x, y)
+	x = math.max(x, y)
+	if x == 0 then return 0 end
+	t = t / x
+	return x * math.sqrt(1 + t * t)
+end
+
+--------------------------------------------------------------------------------
+function get_last_folder(text,count)
+	local parts = text:split(DIR_DELIM)
+	
+	if count == nil then
+		return parts[#parts]
+	end
+	
+	local retval = ""
+	for i=1,count,1 do
+		retval = retval .. parts[#parts - (count-i)] .. DIR_DELIM
+	end
+	
+	return retval
+end
+
+--------------------------------------------------------------------------------
+function cleanup_path(temppath)
+	
+	local parts = temppath:split("-")
+	temppath = ""	
+	for i=1,#parts,1 do
+		if temppath ~= "" then
+			temppath = temppath .. "_"
+		end
+		temppath = temppath .. parts[i]
+	end
+	
+	parts = temppath:split(".")
+	temppath = ""	
+	for i=1,#parts,1 do
+		if temppath ~= "" then
+			temppath = temppath .. "_"
+		end
+		temppath = temppath .. parts[i]
+	end
+	
+	parts = temppath:split("'")
+	temppath = ""	
+	for i=1,#parts,1 do
+		if temppath ~= "" then
+			temppath = temppath .. ""
+		end
+		temppath = temppath .. parts[i]
+	end
+	
+	parts = temppath:split(" ")
+	temppath = ""	
+	for i=1,#parts,1 do
+		if temppath ~= "" then
+			temppath = temppath
+		end
+		temppath = temppath .. parts[i]
+	end
+	
+	return temppath
+end
+
+local tbl = engine or minetest
+function tbl.formspec_escape(text)
+	if text ~= nil then
+		text = string.gsub(text,"\\","\\\\")
+		text = string.gsub(text,"%]","\\]")
+		text = string.gsub(text,"%[","\\[")
+		text = string.gsub(text,";","\\;")
+		text = string.gsub(text,",","\\,")
+	end
+	return text
+end
+
+
+function tbl.splittext(text,charlimit)
+	local retval = {}
+
+	local current_idx = 1
+	
+	local start,stop = string.find(text," ",current_idx)
+	local nl_start,nl_stop = string.find(text,"\n",current_idx)
+	local gotnewline = false
+	if nl_start ~= nil and (start == nil or nl_start < start) then
+		start = nl_start
+		stop = nl_stop
+		gotnewline = true
+	end
+	local last_line = ""
+	while start ~= nil do
+		if string.len(last_line) + (stop-start) > charlimit then
+			table.insert(retval,last_line)
+			last_line = ""
+		end
+		
+		if last_line ~= "" then
+			last_line = last_line .. " "
+		end
+		
+		last_line = last_line .. string.sub(text,current_idx,stop -1)
+		
+		if gotnewline then
+			table.insert(retval,last_line)
+			last_line = ""
+			gotnewline = false
+		end
+		current_idx = stop+1
+		
+		start,stop = string.find(text," ",current_idx)
+		nl_start,nl_stop = string.find(text,"\n",current_idx)
+	
+		if nl_start ~= nil and (start == nil or nl_start < start) then
+			start = nl_start
+			stop = nl_stop
+			gotnewline = true
+		end
+	end
+	
+	--add last part of text
+	if string.len(last_line) + (string.len(text) - current_idx) > charlimit then
+			table.insert(retval,last_line)
+			table.insert(retval,string.sub(text,current_idx))
+	else
+		last_line = last_line .. " " .. string.sub(text,current_idx)
+		table.insert(retval,last_line)
+	end
+	
+	return retval
+end
+
+--------------------------------------------------------------------------------
+
+if minetest then
+	local dirs1 = {9, 18, 7, 12}
+	local dirs2 = {20, 23, 22, 21}
+
+	function minetest.rotate_and_place(itemstack, placer, pointed_thing,
+				infinitestacks, orient_flags)
+		orient_flags = orient_flags or {}
+
+		local unode = minetest.get_node_or_nil(pointed_thing.under)
+		if not unode then
+			return
+		end
+		local undef = minetest.registered_nodes[unode.name]
+		if undef and undef.on_rightclick then
+			undef.on_rightclick(pointed_thing.under, unode, placer,
+					itemstack, pointed_thing)
+			return
+		end
+		local pitch = placer:get_look_pitch()
+		local fdir = minetest.dir_to_facedir(placer:get_look_dir())
+		local wield_name = itemstack:get_name()
+
+		local above = pointed_thing.above
+		local under = pointed_thing.under
+		local iswall = (above.y == under.y)
+		local isceiling = not iswall and (above.y < under.y)
+		local anode = minetest.get_node_or_nil(above)
+		if not anode then
+			return
+		end
+		local pos = pointed_thing.above
+		local node = anode
+
+		if undef and undef.buildable_to then
+			pos = pointed_thing.under
+			node = unode
+			iswall = false
+		end
+
+		if minetest.is_protected(pos, placer:get_player_name()) then
+			minetest.record_protection_violation(pos,
+					placer:get_player_name())
+			return
+		end
+
+		local ndef = minetest.registered_nodes[node.name]
+		if not ndef or not ndef.buildable_to then
+			return
+		end
+
+		if orient_flags.force_floor then
+			iswall = false
+			isceiling = false
+		elseif orient_flags.force_ceiling then
+			iswall = false
+			isceiling = true
+		elseif orient_flags.force_wall then
+			iswall = true
+			isceiling = false
+		elseif orient_flags.invert_wall then
+			iswall = not iswall
+		end
+
+		if iswall then
+			minetest.set_node(pos, {name = wield_name,
+					param2 = dirs1[fdir+1]})
+		elseif isceiling then
+			if orient_flags.force_facedir then
+				minetest.set_node(pos, {name = wield_name,
+						param2 = 20})
+			else
+				minetest.set_node(pos, {name = wield_name,
+						param2 = dirs2[fdir+1]})
+			end
+		else -- place right side up
+			if orient_flags.force_facedir then
+				minetest.set_node(pos, {name = wield_name,
+						param2 = 0})
+			else
+				minetest.set_node(pos, {name = wield_name,
+						param2 = fdir})
+			end
+		end
+
+		if not infinitestacks then
+			itemstack:take_item()
+			return itemstack
+		end
+	end
+
+
+--------------------------------------------------------------------------------
+--Wrapper for rotate_and_place() to check for sneak and assume Creative mode
+--implies infinite stacks when performing a 6d rotation.
+--------------------------------------------------------------------------------
+
+
+	minetest.rotate_node = function(itemstack, placer, pointed_thing)
+		minetest.rotate_and_place(itemstack, placer, pointed_thing,
+				minetest.setting_getbool("creative_mode"),
+				{invert_wall = placer:get_player_control().sneak})
+		return itemstack
+	end
+end
+
+--------------------------------------------------------------------------------
+function tbl.explode_table_event(evt)
+	if evt ~= nil then
+		local parts = evt:split(":")
+		if #parts == 3 then
+			local t = parts[1]:trim()
+			local r = tonumber(parts[2]:trim())
+			local c = tonumber(parts[3]:trim())
+			if type(r) == "number" and type(c) == "number" and t ~= "INV" then
+				return {type=t, row=r, column=c}
+			end
+		end
+	end
+	return {type="INV", row=0, column=0}
+end
+
+--------------------------------------------------------------------------------
+function tbl.explode_textlist_event(evt)
+	if evt ~= nil then
+		local parts = evt:split(":")
+		if #parts == 2 then
+			local t = parts[1]:trim()
+			local r = tonumber(parts[2]:trim())
+			if type(r) == "number" and t ~= "INV" then
+				return {type=t, index=r}
+			end
+		end
+	end
+	return {type="INV", index=0}
+end
+
+--------------------------------------------------------------------------------
+-- mainmenu only functions
+--------------------------------------------------------------------------------
+if engine ~= nil then
+	engine.get_game = function(index)
+		local games = game.get_games()
+		
+		if index > 0 and index <= #games then
+			return games[index]
+		end
+		
+		return nil
+	end
+	
+	function fgettext(text, ...)
+		text = engine.gettext(text)
+		local arg = {n=select('#', ...), ...}
+		if arg.n >= 1 then
+			-- Insert positional parameters ($1, $2, ...)
+			result = ''
+			pos = 1
+			while pos <= text:len() do
+				newpos = text:find('[$]', pos)
+				if newpos == nil then
+					result = result .. text:sub(pos)
+					pos = text:len() + 1
+				else
+					paramindex = tonumber(text:sub(newpos+1, newpos+1))
+					result = result .. text:sub(pos, newpos-1) .. tostring(arg[paramindex])
+					pos = newpos + 2
+				end
+			end
+			text = result
+		end
+		return engine.formspec_escape(text)
+	end
+end
+--------------------------------------------------------------------------------
+-- core only fct
+--------------------------------------------------------------------------------
+if minetest ~= nil then
+	--------------------------------------------------------------------------------
+	function minetest.pos_to_string(pos)
+		return "(" .. pos.x .. "," .. pos.y .. "," .. pos.z .. ")"
+	end
+end
+
diff --git a/builtin/common/serialize.lua b/builtin/common/serialize.lua
new file mode 100644
index 000000000..93fffe80d
--- /dev/null
+++ b/builtin/common/serialize.lua
@@ -0,0 +1,223 @@
+-- Minetest: builtin/serialize.lua
+
+-- https://github.com/fab13n/metalua/blob/no-dll/src/lib/serialize.lua
+-- Copyright (c) 2006-2997 Fabien Fleutot <metalua@gmail.com>
+-- License: MIT
+--------------------------------------------------------------------------------
+-- Serialize an object into a source code string. This string, when passed as
+-- an argument to deserialize(), returns an object structurally identical
+-- to the original one. The following are currently supported:
+-- * strings, numbers, booleans, nil
+-- * tables thereof. Tables can have shared part, but can't be recursive yet.
+-- Caveat: metatables and environments aren't saved.
+--------------------------------------------------------------------------------
+
+local no_identity = { number=1, boolean=1, string=1, ['nil']=1 }
+
+function minetest.serialize(x)
+
+	local gensym_max   =  0  -- index of the gensym() symbol generator
+	local seen_once    = { } -- element->true set of elements seen exactly once in the table
+	local multiple     = { } -- element->varname set of elements seen more than once
+	local nested       = { } -- transient, set of elements currently being traversed
+	local nest_points  = { }
+	local nest_patches = { }
+	
+	local function gensym()
+		gensym_max = gensym_max + 1 ;  return gensym_max
+	end
+
+	-----------------------------------------------------------------------------
+	-- nest_points are places where a table appears within itself, directly or not.
+	-- for instance, all of these chunks create nest points in table x:
+	-- "x = { }; x[x] = 1", "x = { }; x[1] = x", "x = { }; x[1] = { y = { x } }".
+	-- To handle those, two tables are created by mark_nest_point:
+	-- * nest_points [parent] associates all keys and values in table parent which
+	--   create a nest_point with boolean `true'
+	-- * nest_patches contain a list of { parent, key, value } tuples creating
+	--   a nest point. They're all dumped after all the other table operations
+	--   have been performed.
+	--
+	-- mark_nest_point (p, k, v) fills tables nest_points and nest_patches with
+	-- informations required to remember that key/value (k,v) create a nest point
+	-- in table parent. It also marks `parent' as occuring multiple times, since
+	-- several references to it will be required in order to patch the nest
+	-- points.
+	-----------------------------------------------------------------------------
+	local function mark_nest_point (parent, k, v)
+		local nk, nv = nested[k], nested[v]
+		assert (not nk or seen_once[k] or multiple[k])
+		assert (not nv or seen_once[v] or multiple[v])
+		local mode = (nk and nv and "kv") or (nk and "k") or ("v")
+		local parent_np = nest_points [parent]
+		local pair = { k, v }
+		if not parent_np then parent_np = { }; nest_points [parent] = parent_np end
+		parent_np [k], parent_np [v] = nk, nv
+		table.insert (nest_patches, { parent, k, v })
+		seen_once [parent], multiple [parent]  = nil, true
+	end
+
+	-----------------------------------------------------------------------------
+	-- First pass, list the tables and functions which appear more than once in x
+	-----------------------------------------------------------------------------
+	local function mark_multiple_occurences (x)
+		if no_identity [type(x)] then return end
+		if     seen_once [x]     then seen_once [x], multiple [x] = nil, true
+		elseif multiple  [x]     then -- pass
+		else   seen_once [x] = true end
+		
+		if type (x) == 'table' then
+			nested [x] = true
+			for k, v in pairs (x) do
+				if nested[k] or nested[v] then mark_nest_point (x, k, v) else
+					mark_multiple_occurences (k)
+					mark_multiple_occurences (v)
+				end
+			end
+			nested [x] = nil
+		end
+	end
+
+	local dumped    = { } -- multiply occuring values already dumped in localdefs
+	local localdefs = { } -- already dumped local definitions as source code lines
+
+	-- mutually recursive functions:
+	local dump_val, dump_or_ref_val
+
+	--------------------------------------------------------------------
+	-- if x occurs multiple times, dump the local var rather than the
+	-- value. If it's the first time it's dumped, also dump the content
+	-- in localdefs.
+	--------------------------------------------------------------------
+	function dump_or_ref_val (x)
+		if nested[x] then return 'false' end -- placeholder for recursive reference
+		if not multiple[x] then return dump_val (x) end
+		local var = dumped [x]
+		if var then return "_[" .. var .. "]" end -- already referenced
+		local val = dump_val(x) -- first occurence, create and register reference
+		var = gensym()
+		table.insert(localdefs, "_["..var.."]="..val)
+		dumped [x] = var
+		return "_[" .. var .. "]"
+	end
+
+	-----------------------------------------------------------------------------
+	-- Second pass, dump the object; subparts occuring multiple times are dumped
+	-- in local variables which can be referenced multiple times;
+	-- care is taken to dump locla vars in asensible order.
+	-----------------------------------------------------------------------------
+	function dump_val(x)
+		local  t = type(x)
+		if     x==nil        then return 'nil'
+		elseif t=="number"   then return tostring(x)
+		elseif t=="string"   then return string.format("%q", x)
+		elseif t=="boolean"  then return x and "true" or "false"
+		elseif t=="function" then
+			return "loadstring("..string.format("%q", string.dump(x))..")"
+		elseif t=="table" then
+			local acc        = { }
+			local idx_dumped = { }
+			local np         = nest_points [x]
+			for i, v in ipairs(x) do
+				if np and np[v] then
+					table.insert (acc, 'false') -- placeholder
+				else
+					table.insert (acc, dump_or_ref_val(v))
+				end
+				idx_dumped[i] = true
+			end
+			for k, v in pairs(x) do
+				if np and (np[k] or np[v]) then
+					--check_multiple(k); check_multiple(v) -- force dumps in localdefs
+				elseif not idx_dumped[k] then
+					table.insert (acc, "[" .. dump_or_ref_val(k) .. "] = " .. dump_or_ref_val(v))
+				end
+			end
+			return "{ "..table.concat(acc,", ").." }"
+		else
+			error ("Can't serialize data of type "..t)
+		end
+	end
+	
+	local function dump_nest_patches()
+		for _, entry in ipairs(nest_patches) do
+			local p, k, v = unpack (entry)
+			assert (multiple[p])
+			local set = dump_or_ref_val (p) .. "[" .. dump_or_ref_val (k) .. "] = " .. 
+				dump_or_ref_val (v) .. " -- rec "
+			table.insert (localdefs, set)
+		end
+	end
+
+	mark_multiple_occurences (x)
+	local toplevel = dump_or_ref_val (x)
+	dump_nest_patches()
+
+	if next (localdefs) then
+		return "local _={ }\n" ..
+			table.concat (localdefs, "\n") .. 
+			"\nreturn " .. toplevel
+	else
+		return "return " .. toplevel
+	end
+end
+
+-- Deserialization.
+-- http://stackoverflow.com/questions/5958818/loading-serialized-data-into-a-table
+--
+
+local env = {
+	loadstring = loadstring,
+}
+
+local function noop() end
+
+local safe_env = {
+	loadstring = noop,
+}
+
+local function stringtotable(sdata, safe)
+	if sdata:byte(1) == 27 then return nil, "binary bytecode prohibited" end
+	local f, message = assert(loadstring(sdata))
+	if not f then return nil, message end
+	if safe then
+		setfenv(f, safe_env)
+	else
+		setfenv(f, env)
+	end
+	return f()
+end
+
+function minetest.deserialize(sdata, safe)
+	local table = {}
+	local okay, results = pcall(stringtotable, sdata, safe)
+	if okay then
+		return results
+	end
+	minetest.log('error', 'minetest.deserialize(): '.. results)
+	return nil
+end
+
+-- Run some unit tests
+local function unit_test()
+	function unitTest(name, success)
+		if not success then
+			error(name .. ': failed')
+		end
+	end
+
+	unittest_input = {cat={sound="nyan", speed=400}, dog={sound="woof"}}
+	unittest_output = minetest.deserialize(minetest.serialize(unittest_input))
+
+	unitTest("test 1a", unittest_input.cat.sound == unittest_output.cat.sound)
+	unitTest("test 1b", unittest_input.cat.speed == unittest_output.cat.speed)
+	unitTest("test 1c", unittest_input.dog.sound == unittest_output.dog.sound)
+
+	unittest_input = {escapechars="\n\r\t\v\\\"\'", noneuropean="θשׁ٩∂"}
+	unittest_output = minetest.deserialize(minetest.serialize(unittest_input))
+	unitTest("test 3a", unittest_input.escapechars == unittest_output.escapechars)
+	unitTest("test 3b", unittest_input.noneuropean == unittest_output.noneuropean)
+end
+unit_test() -- Run it
+unit_test = nil -- Hide it
+
diff --git a/builtin/common/vector.lua b/builtin/common/vector.lua
new file mode 100644
index 000000000..77944b612
--- /dev/null
+++ b/builtin/common/vector.lua
@@ -0,0 +1,146 @@
+
+vector = {}
+
+local function assert_vector(v)
+	assert(type(v) == "table" and v.x and v.y and v.z, "Invalid vector")
+end
+
+function vector.new(a, b, c)
+	if type(a) == "table" then
+		assert(a.x and a.y and a.z, "Invalid vector passed to vector.new()")
+		return {x=a.x, y=a.y, z=a.z}
+	elseif a then
+		assert(b and c, "Invalid arguments for vector.new()")
+		return {x=a, y=b, z=c}
+	end
+	return {x=0, y=0, z=0}
+end
+
+function vector.equals(a, b)
+	assert_vector(a)
+	assert_vector(b)
+	return a.x == b.x and
+	       a.y == b.y and
+	       a.z == b.z
+end
+
+function vector.length(v)
+	assert_vector(v)
+	return math.hypot(v.x, math.hypot(v.y, v.z))
+end
+
+function vector.normalize(v)
+	assert_vector(v)
+	local len = vector.length(v)
+	if len == 0 then
+		return {x=0, y=0, z=0}
+	else
+		return vector.divide(v, len)
+	end
+end
+
+function vector.round(v)
+	assert_vector(v)
+	return {
+		x = math.floor(v.x + 0.5),
+		y = math.floor(v.y + 0.5),
+		z = math.floor(v.z + 0.5)
+	}
+end
+
+function vector.distance(a, b)
+	assert_vector(a)
+	assert_vector(b)
+	local x = a.x - b.x
+	local y = a.y - b.y
+	local z = a.z - b.z
+	return math.hypot(x, math.hypot(y, z))
+end
+
+function vector.direction(pos1, pos2)
+	assert_vector(pos1)
+	assert_vector(pos2)
+	local x_raw = pos2.x - pos1.x
+	local y_raw = pos2.y - pos1.y
+	local z_raw = pos2.z - pos1.z
+	local x_abs = math.abs(x_raw)
+	local y_abs = math.abs(y_raw)
+	local z_abs = math.abs(z_raw)
+	if x_abs >= y_abs and
+	   x_abs >= z_abs then
+		y_raw = y_raw * (1 / x_abs)
+		z_raw = z_raw * (1 / x_abs)
+		x_raw = x_raw / x_abs
+	end
+	if y_abs >= x_abs and
+	   y_abs >= z_abs then
+		x_raw = x_raw * (1 / y_abs)
+		z_raw = z_raw * (1 / y_abs)
+		y_raw = y_raw / y_abs
+	end
+	if z_abs >= y_abs and
+	   z_abs >= x_abs then
+		x_raw = x_raw * (1 / z_abs)
+		y_raw = y_raw * (1 / z_abs)
+		z_raw = z_raw / z_abs
+	end
+	return {x=x_raw, y=y_raw, z=z_raw}
+end
+
+
+function vector.add(a, b)
+	assert_vector(a)
+	if type(b) == "table" then
+	    assert_vector(b)
+		return {x = a.x + b.x,
+			y = a.y + b.y,
+			z = a.z + b.z}
+	else
+		return {x = a.x + b,
+			y = a.y + b,
+			z = a.z + b}
+	end
+end
+
+function vector.subtract(a, b)
+	assert_vector(a)
+	if type(b) == "table" then
+	    assert_vector(b)
+		return {x = a.x - b.x,
+			y = a.y - b.y,
+			z = a.z - b.z}
+	else
+		return {x = a.x - b,
+			y = a.y - b,
+			z = a.z - b}
+	end
+end
+
+function vector.multiply(a, b)
+	assert_vector(a)
+	if type(b) == "table" then
+	    assert_vector(b)
+		return {x = a.x * b.x,
+			y = a.y * b.y,
+			z = a.z * b.z}
+	else
+		return {x = a.x * b,
+			y = a.y * b,
+			z = a.z * b}
+	end
+end
+
+function vector.divide(a, b)
+	assert_vector(a)
+	if type(b) == "table" then
+        assert_vector(b)
+		return {x = a.x / b.x,
+			y = a.y / b.y,
+			z = a.z / b.z}
+	else
+		return {x = a.x / b,
+			y = a.y / b,
+			z = a.z / b}
+	end
+end
+