SaferLua Robot added

sl_robot/base.lua

@@ -0,0 +1,452 @@
+--[[
+
+	sl_robot
+	========
+
+	Copyright (C) 2018 Joachim Stolberg
+
+	LGPLv2.1+
+	See LICENSE.txt for more information
+
+	base.lua:
+
+]]--
+
+local FUEL_AMOUNT = 1000000
+
+local sHELP = [[SaferLua Robot
+
+ The SaferLua Robot can be programmed in Lua by
+ means of this Robot Base.
+ The Robot needs Bio Fluel to operate.
+ 
+]]
+
+local Cache = {}
+
+local tCommands = {}
+local tFunctions = {" Overview", " Data structures"}
+local tHelpTexts = {[" Overview"] = sHELP, [" Data structures"] = safer_lua.DataStructHelp}
+local sFunctionList = ""
+local tFunctionIndex = {}
+
+minetest.after(2, function() 
+	sFunctionList = table.concat(tFunctions, ",") 
+	for idx,key in ipairs(tFunctions) do
+		tFunctionIndex[key] = idx
+	end
+end)
+
+local function output(pos, text)
+	local meta = minetest.get_meta(pos)
+	text = meta:get_string("output") .. "\n" .. (text or "")
+	text = text:sub(-500,-1)
+	meta:set_string("output", text)
+end
+
+--
+-- API functions for function/action registrations
+--
+function sl_robot.register_action(key, attr)
+	tCommands[key] = attr.cmnd
+	table.insert(tFunctions, " $"..key)
+	tHelpTexts[" $"..key] = attr.help
+end
+
+local function merge(dest, keys, values)
+  for idx,key in ipairs(keys) do
+    dest.env[key] = values[idx]
+  end
+  return dest
+end
+
+sl_robot.register_action("print", {
+	cmnd = function(self, text1, text2, text3)
+		local pos = self.meta.pos
+		text1 = tostring(text1 or "")
+		text2 = tostring(text2 or "")
+		text3 = tostring(text3 or "")
+		output(pos, text1..text2..text3)
+	end,
+	help = " $print(text,...)\n"..
+		" Send a text line to the output window.\n"..
+		" The function accepts up to 3 text strings\n"..
+		' e.g. $print("Hello ", name, " !")'
+})
+
+
+local function allow_metadata_inventory_put(pos, listname, index, stack, player)
+	if minetest.is_protected(pos, player:get_player_name()) then
+		return 0
+	end
+	local meta = minetest.get_meta(pos)
+	if meta:get_int("state") == tubelib.RUNNING then
+		return 0
+	end
+	local inv = meta:get_inventory()
+	if listname == "main" then
+		return stack:get_count()
+	elseif listname == "fuel" and stack:get_name() == "tubelib_addons1:biofuel" then
+		return stack:get_count()
+	end
+	return 0
+end
+
+local function allow_metadata_inventory_take(pos, listname, index, stack, player)
+	if minetest.is_protected(pos, player:get_player_name()) then
+		return 0
+	end
+	local meta = minetest.get_meta(pos)
+	if meta:get_int("state") == tubelib.RUNNING then
+		return 0
+	end
+	return stack:get_count()
+end
+
+local function formspec1(meta)
+	local running = meta:get_int("state") == tubelib.RUNNING
+	local cmnd = running and "stop;Stop" or "start;Start" 
+	local init = meta:get_string("init")
+	local fuel = math.floor((meta:get_int("fuel") * 100.0) / FUEL_AMOUNT) 
+	init = minetest.formspec_escape(init)
+	return "size[10,8]"..
+	default.gui_bg..
+	default.gui_bg_img..
+	default.gui_slots..
+	"tabheader[0,0;tab;Inv,init,loop,outp,notes,help;1;;true]"..
+	"label[5.3,0.5;1]label[6.3,0.5;2]label[7.3,0.5;3]label[8.3,0.5;4]"..
+	"list[context;main;5,1;4,2;]"..
+	"label[5.3,3;5]label[6.3,3;6]label[7.3,3;7]label[8.3,3;8]"..
+	"list[context;fuel;1,1.7;1,1;]"..
+	"item_image[1,1.7;1,1;tubelib_addons1:biofuel]"..
+	"image[2,1.7;1,1;default_furnace_fire_bg.png^[lowpart:"..
+	(fuel)..":default_furnace_fire_fg.png]"..
+	"list[current_player;main;1,4;8,4;]"..
+	"listring[context;main]"..
+	"listring[current_player;main]"
+
+end
+
+local function formspec2(meta)
+	local running = meta:get_int("state") == tubelib.RUNNING
+	local cmnd = running and "stop;Stop" or "start;Start" 
+	local init = meta:get_string("init")
+	init = minetest.formspec_escape(init)
+	return "size[10,8]"..
+	default.gui_bg..
+	default.gui_bg_img..
+	default.gui_slots..
+	"tabheader[0,0;tab;Inv,init,loop,outp,notes,help;2;;true]"..
+	"textarea[0.3,0.2;10,8.3;init;function init();"..init.."]"..
+	"label[0,7.3;end]"..
+	"button_exit[4.4,7.5;1.8,1;cancel;Cancel]"..
+	"button[6.3,7.5;1.8,1;save;Save]"..
+	"button[8.2,7.5;1.8,1;"..cmnd.."]"
+end
+
+local function formspec3(meta)
+	local running = meta:get_int("state") == tubelib.RUNNING
+	local cmnd = running and "stop;Stop" or "start;Start"
+	local loop = meta:get_string("loop")
+	loop = minetest.formspec_escape(loop)
+	return "size[10,8]"..
+	default.gui_bg..
+	default.gui_bg_img..
+	default.gui_slots..
+	"tabheader[0,0;tab;Inv,init,loop,outp,notes,help;3;;true]"..
+	"textarea[0.3,0.2;10,8.3;loop;function loop(ticks, elapsed);"..loop.."]"..
+	"label[0,7.3;end]"..
+	"button_exit[4.4,7.5;1.8,1;cancel;Cancel]"..
+	"button[6.3,7.5;1.8,1;save;Save]"..
+	"button[8.2,7.5;1.8,1;"..cmnd.."]"
+end
+
+local function formspec4(meta)
+	local running = meta:get_int("state") == tubelib.RUNNING
+	local cmnd = running and "stop;Stop" or "start;Start" 
+	local output = meta:get_string("output")
+	output = minetest.formspec_escape(output)
+	return "size[10,8]"..
+	default.gui_bg..
+	default.gui_bg_img..
+	default.gui_slots..
+	"tabheader[0,0;tab;Inv,init,loop,outp,notes,help;4;;true]"..
+	"textarea[0.3,0.2;10,8.3;help;Output:;"..output.."]"..
+	"button[4.4,7.5;1.8,1;clear;Clear]"..
+	"button[6.3,7.5;1.8,1;update;Update]"..
+	"button[8.2,7.5;1.8,1;"..cmnd.."]"
+end
+
+local function formspec5(meta)
+	local notes = meta:get_string("notes")
+	notes = minetest.formspec_escape(notes)
+	return "size[10,8]"..
+	default.gui_bg..
+	default.gui_bg_img..
+	default.gui_slots..
+	"tabheader[0,0;tab;Inv,init,loop,outp,notes,help;5;;true]"..
+	"textarea[0.3,0.2;10,8.3;notes;Notepad:;"..notes.."]"..
+	"button_exit[6.3,7.5;1.8,1;cancel;Cancel]"..
+	"button[8.2,7.5;1.8,1;save;Save]"
+end
+
+local function formspec6(items, pos, text)
+	text = minetest.formspec_escape(text)
+	return "size[10,8]"..
+	default.gui_bg..
+	default.gui_bg_img..
+	default.gui_slots..
+	"tabheader[0,0;tab;Inv,init,loop,outp,notes,help;6;;true]"..
+	"label[0,-0.2;Functions:]"..
+	"dropdown[0.3,0.2;10,8.3;functions;"..items..";"..pos.."]"..
+	"textarea[0.3,1.3;10,8;help;Help:;"..text.."]"
+end
+
+local function error(pos, err)
+	output(pos, err)
+	local meta = minetest.get_meta(pos)
+	local number = meta:get_string("number")
+	meta:set_string("formspec", formspec4(meta))
+	meta:set_string("infotext", "Robot Base "..number..": error")
+	meta:set_int("state", tubelib.STOPPED)
+	minetest.get_node_timer(pos):stop()
+	local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+	minetest.sound_play('sl_robot_error', {pos = robot_pos})
+	return false
+end
+
+-- check the fuel level and return false if empty
+local function check_fuel(pos, meta)
+	local fuel = meta:get_int("fuel")
+	if fuel <= 0 then
+		if tubelib.get_this_item(meta, "fuel", 1) == nil then
+			return false
+		end
+		fuel = FUEL_AMOUNT
+	end
+	meta:set_int("fuel", fuel)
+	return true
+end
+
+local function reset_robot(pos, meta)
+	print("robot_pos", meta:get_string("robot_pos"))
+	local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+	if robot_pos then
+		sl_robot.remove_robot(robot_pos)
+	end
+	local param2 = (minetest.get_node(pos).param2 + 1) % 4
+	robot_pos = sl_robot.new_pos(pos, param2, 1)
+	local pos_below = {x=robot_pos.x, y=robot_pos.y-1, z=robot_pos.z}
+	
+	meta:set_string("robot_pos", minetest.pos_to_string(robot_pos))
+	meta:set_int("robot_param2", param2)
+	sl_robot.place_robot(robot_pos, pos_below, param2, nil)	
+end
+
+
+local function compile(pos, meta, number)
+	local init = meta:get_string("init")
+	local loop = meta:get_string("loop")
+	local owner = meta:get_string("owner")
+	local env = table.copy(tCommands)
+	reset_robot(pos, meta)
+	env.meta = {pos=pos, owner=owner, number=number, error=error}
+	local co, code = safer_lua.co_create(pos, init, loop, env, error)
+	
+	if co then
+		Cache[number] = {code=code, co=co}
+		return true
+	end
+	return false
+end
+
+local function start_robot(pos)
+	local meta = minetest.get_meta(pos)
+	local number = meta:get_string("number")
+	
+	meta:set_string("output", "<press update>")
+	
+	if not check_fuel(pos, meta) then 
+		local number = meta:get_string("number")
+		meta:set_string("infotext", "Robot Base "..number..": no fuel")
+		return false 
+	end
+	if compile(pos, meta, number) then
+		meta:set_int("state", tubelib.RUNNING)
+		meta:set_string("formspec", formspec4(meta))
+		minetest.get_node_timer(pos):start(1)
+		meta:set_string("infotext", "Robot Base "..number..": running")
+		return true
+	end
+	return false
+end
+
+local function stop_robot(pos)
+	local meta = minetest.get_meta(pos)
+	local number = meta:get_string("number")
+	local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+	meta:set_int("state", tubelib.STOPPED)
+	minetest.get_node_timer(pos):stop()
+	meta:set_string("infotext", "Robot Base "..number..": stopped")
+	meta:set_string("formspec", formspec3(meta))
+	if Cache[number] then
+		local code =  Cache[number].code
+		local env = getfenv(code)
+		sl_robot.remove_robot(robot_pos)
+	end
+end
+
+local function call_loop(pos, meta, elapsed)
+	local t = minetest.get_us_time()
+	local number = meta:get_string("number")
+	if Cache[number] or compile(pos, meta, number) then
+		local cpu = meta:get_int("cpu") or 0
+		local code = Cache[number].code
+		local co = Cache[number].co
+		local res = safer_lua.co_resume(pos, co, code, error)
+		if res then 
+			t = minetest.get_us_time() - t
+			cpu = math.floor(((cpu * 20) + t) / 21)
+			meta:set_int("cpu", cpu)
+			local robot_pos = meta:get_string("robot_pos")
+			meta:set_string("infotext", "Robot Base "..number..": running ("..cpu.."us) "..robot_pos)
+			meta:set_int("fuel", meta:get_int("fuel") - t)
+		end
+		return res
+	end
+	return false
+end
+
+local function on_timer(pos, elapsed)
+	local meta = minetest.get_meta(pos)
+	
+	--so some maintenance every 10 cycles
+	local ticks = (meta:get_int("ticks") or 0) + 1
+	meta:set_int("ticks", ticks)
+	if (ticks % 100) == 0 then
+		if not check_fuel(pos, meta) then 
+			local number = meta:get_string("number")
+			meta:set_string("infotext", "Robot Base "..number..": no fuel")
+			return false 
+		end
+	end
+	return call_loop(pos, meta, elapsed)
+end
+
+local function on_receive_fields(pos, formname, fields, player)
+	if minetest.is_protected(pos, player:get_player_name()) then
+		return
+	end
+	local meta = minetest.get_meta(pos)
+	
+	--print(dump(fields))
+	if fields.cancel == nil then
+		if fields.init then
+			meta:set_string("init", fields.init)
+			meta:set_string("formspec", formspec2(meta))
+		elseif fields.loop then
+			meta:set_string("loop", fields.loop)
+			meta:set_string("formspec", formspec3(meta))
+		elseif fields.notes then
+			meta:set_string("notes", fields.notes)
+			meta:set_string("formspec", formspec5(meta))
+		end	
+	end
+	
+	if fields.update then
+		meta:set_string("formspec", formspec4(meta))
+	elseif fields.clear then
+		meta:set_string("output", "<press update>")
+		meta:set_string("formspec", formspec4(meta))
+	elseif fields.tab == "1" then
+		meta:set_string("formspec", formspec1(meta))
+	elseif fields.tab == "2" then
+		meta:set_string("formspec", formspec2(meta))
+	elseif fields.tab == "3" then
+		meta:set_string("formspec", formspec3(meta))
+	elseif fields.tab == "4" then
+		meta:set_string("formspec", formspec4(meta))
+	elseif fields.tab == "5" then
+		meta:set_string("formspec", formspec5(meta))
+	elseif fields.tab == "6" then
+		meta:set_string("formspec", formspec6(sFunctionList, 1, sHELP))
+	elseif fields.start == "Start" then
+		start_robot(pos)
+		minetest.log("action", player:get_player_name() ..
+			" starts the sl_robot at ".. minetest.pos_to_string(pos))
+	elseif fields.stop == "Stop" then
+		stop_robot(pos)
+	elseif fields.functions then
+		local key = fields.functions
+		local text = tHelpTexts[key] or ""
+		local pos = tFunctionIndex[key] or 1
+		meta:set_string("formspec", formspec6(sFunctionList, pos, text))
+	end
+end
+
+minetest.register_node("sl_robot:base", {
+	description = "SaferLua Robot Base",
+	stack_max = 1,
+	tiles = {
+		-- up, down, right, left, back, front
+		'sl_robot_base_top.png',
+		'sl_robot_base_top.png',
+		'sl_robot_base_right.png',
+		'sl_robot_base_left.png',
+		'sl_robot_base_front.png',
+		'sl_robot_base_front.png',
+	},
+
+	on_construct = function(pos)
+		local meta = minetest.get_meta(pos)
+		local inv = meta:get_inventory()
+		inv:set_size('main', 8)
+		inv:set_size('fuel', 1)
+	end,
+	
+	after_place_node = function(pos, placer)
+		local meta = minetest.get_meta(pos)
+		local number = tubelib.add_node(pos, "sl_robot:base")
+		meta:set_string("owner", placer:get_player_name())
+		meta:set_string("number", number)
+		meta:set_int("state", tubelib.STOPPED)
+		meta:set_string("init", "-- called only once")
+		meta:set_string("loop", "-- called cyclically")
+		meta:set_string("notes", "For your notes / snippets")
+		meta:set_string("formspec", formspec1(meta))
+		meta:set_string("infotext", "Robot Base "..number..": stopped")
+	end,
+
+	on_receive_fields = on_receive_fields,
+	
+	on_dig = function(pos, node, puncher, pointed_thing)
+		if minetest.is_protected(pos, puncher:get_player_name()) then
+			return
+		end
+		local meta = minetest.get_meta(pos)
+		if meta:get_int("state") == tubelib.RUNNING then
+			return
+		end
+		minetest.node_dig(pos, node, puncher, pointed_thing)
+		tubelib.remove_node(pos)
+	end,
+	
+	on_timer = on_timer,
+	allow_metadata_inventory_put = allow_metadata_inventory_put,
+	allow_metadata_inventory_take = allow_metadata_inventory_take,
+	
+	paramtype = "light",
+	sunlight_propagates = true,
+	paramtype2 = "facedir",
+	is_ground_content = false,
+	groups = {cracky = 1},
+	sounds = default.node_sound_metal_defaults(),
+})
+
+
+--minetest.register_craft({
+--	type = "shapeless",
+--	output = "sl_robot:robot",
+--	recipe = {"smartline:controller"}
+--})
+

sl_robot/commands.lua

@@ -0,0 +1,115 @@
+--[[
+
+	sl_robot
+	========
+
+	Copyright (C) 2018 Joachim Stolberg
+
+	LGPLv2.1+
+	See LICENSE.txt for more information
+
+	commands.lua:
+	
+	Register all robot commands
+
+]]--
+
+
+sl_robot.register_action("get_ms_time", {
+	cmnd = function(self)
+		return math.floor(minetest.get_us_time() / 1000)
+	end,
+	help = "$get_ms_time()\n"..
+		" returns time with millisecond precision."
+})
+
+sl_robot.register_action("forward", {
+	cmnd = function(self, steps)
+		steps = tonumber(steps or 1)
+		local idx = 1
+		while idx <= steps do
+			local meta = minetest.get_meta(self.meta.pos)
+			local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+			local robot_param2 = meta:get_int("robot_param2")
+			local new_pos = sl_robot.move_robot(robot_pos, robot_param2, 1)
+			if new_pos then  -- not blocked?
+				if new_pos.y == robot_pos.y then  -- forward move?
+					idx = idx + 1
+				end
+				meta:set_string("robot_pos", minetest.pos_to_string(new_pos))
+			else  -- blocked
+				-- because of unloaded areas and the LBM replace blocked robots
+				--minetest.set_node(robot_pos, {name = "sl_robot:robot_dummy", param2 = robot_param2})
+			end
+			coroutine.yield()
+		end
+	end,
+	help = "tbd"
+})
+
+sl_robot.register_action("left", {
+	cmnd = function(self)
+		local meta = minetest.get_meta(self.meta.pos)
+		local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+		local robot_param2 = meta:get_int("robot_param2")
+		robot_param2 = sl_robot.turn_robot(robot_pos, robot_param2, "L")
+		meta:set_int("robot_param2", robot_param2)
+		coroutine.yield()
+	end,
+	help = "tbd"
+})
+
+sl_robot.register_action("right", {
+	cmnd = function(self)
+		local meta = minetest.get_meta(self.meta.pos)
+		local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+		local robot_param2 = meta:get_int("robot_param2")
+		robot_param2 = sl_robot.turn_robot(robot_pos, robot_param2, "R")
+		meta:set_int("robot_param2", robot_param2)
+		coroutine.yield()
+	end,
+	help = "tbd"
+})
+
+sl_robot.register_action("up", {
+	cmnd = function(self)
+		local meta = minetest.get_meta(self.meta.pos)
+		local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+		local robot_param2 = meta:get_int("robot_param2")
+		local new_pos
+		while true do
+			new_pos = sl_robot.robot_up(robot_pos, robot_param2)
+			if new_pos then break end
+			coroutine.yield()
+		end
+		meta:set_string("robot_pos", minetest.pos_to_string(new_pos))
+		coroutine.yield()
+	end,
+	help = "tbd"
+})
+
+sl_robot.register_action("down", {
+	cmnd = function(self)
+		local meta = minetest.get_meta(self.meta.pos)
+		local robot_pos = minetest.string_to_pos(meta:get_string("robot_pos"))
+		local robot_param2 = meta:get_int("robot_param2")
+		while true do
+			new_pos = sl_robot.robot_down(robot_pos, robot_param2)
+			if new_pos then break end
+			coroutine.yield()
+		end
+		meta:set_string("robot_pos", minetest.pos_to_string(new_pos))
+		coroutine.yield()
+	end,
+	help = "tbd"
+})
+
+sl_robot.register_action("stop", {
+	cmnd = function(self)
+		while true do
+			coroutine.yield()
+		end
+	end,
+	help = "tbd"
+})
+

sl_robot/depends.txt

@@ -0,0 +1,4 @@
+default
+tubelib
+safer_lua
+

sl_robot/description.txt

@@ -0,0 +1,2 @@
+SaferLua Robot - a simple robot to be programmed in LUA
+

sl_robot/init.lua

@@ -0,0 +1,18 @@
+--[[
+
+	sl_robot
+	========
+	
+	Copyright (C) 2018 Joachim Stolberg
+
+	LGPLv2.1+
+	See LICENSE.txt for more information
+
+]]--
+
+sl_robot = {}
+
+--dofile(minetest.get_modpath("sl_robot") .. "/config.lua")
+dofile(minetest.get_modpath("sl_robot") .. "/robot.lua")
+dofile(minetest.get_modpath("sl_robot") .. "/base.lua")
+dofile(minetest.get_modpath("sl_robot") .. "/commands.lua")

sl_robot/mod.conf

@@ -0,0 +1 @@
+name=sl_robot

sl_robot/readme.md

@@ -0,0 +1,19 @@
+SaferLua Robot [sl_robot]
+=========================
+
+
+A tubelib compatible robot to be programmed in LUA
+
+The mod uses SaferLua [safer_lua] as Lua sandbox for safe and secure code execution.
+
+
+### License
+Copyright (C) 2018 Joachim Stolberg  
+Code: Licensed under the GNU LGPL version 2.1 or later. See LICENSE.txt  
+
+
+### Dependencies 
+tubelib, safer_lua
+
+### History
+- 2018-07-06  v0.01  * first draft

sl_robot/robot.lua

@@ -0,0 +1,282 @@
+--[[
+
+	sl_robot
+	========
+
+	Copyright (C) 2018 Joachim Stolberg
+
+	LGPLv2.1+
+	See LICENSE.txt for more information
+
+	robot.lua:
+
+]]--
+
+local Face2Dir = {[0]=
+	{x=0,  y=0,  z=1},
+	{x=1,  y=0,  z=0},
+	{x=0,  y=0, z=-1},
+	{x=-1, y=0,  z=0},
+	{x=0,  y=-1, z=0},
+	{x=0,  y=1,  z=0}
+}
+
+function sl_robot.new_pos(pos, param2, step)
+	return vector.add(pos, vector.multiply(Face2Dir[param2], step))
+end
+
+-- use Voxel Manipulator to read the node
+local function read_node_with_vm(pos)
+	local vm = VoxelManip()
+	local MinEdge, MaxEdge = vm:read_from_map(pos, pos)
+	local data = vm:get_data()
+	local area = VoxelArea:new({MinEdge = MinEdge, MaxEdge = MaxEdge})
+	return {
+		name = minetest.get_name_from_content_id(data[area:index(pos.x, pos.y, pos.z)])
+	}
+end
+
+-- check is posA == air-like and posB == solid and no player around
+local function check_pos(posA, posB)
+	local nodeA = minetest.get_node_or_nil(posA) or read_node_with_vm(posA)
+	local nodeB = minetest.get_node_or_nil(posB) or read_node_with_vm(posB)
+	if not minetest.registered_nodes[nodeA.name].walkable and 
+			minetest.registered_nodes[nodeB.name].walkable then
+		local objects = minetest.get_objects_inside_radius(posA, 1)
+		if #objects ~= 0 then
+			minetest.sound_play('sl_robot_go_away', {pos = posA})
+			return false
+		else
+			return true
+		end
+	end
+	return false
+end
+
+function sl_robot.place_robot(pos1, pos2, param2, player_name)	
+	if check_pos(pos1, pos2) then
+		minetest.set_node(pos1, {name = "sl_robot:robot", param2 = param2})
+	end
+end
+
+function sl_robot.remove_robot(pos)	
+	local node = minetest.get_node(pos)
+	if node.name == "sl_robot:robot" or node.name == "sl_robot:robot_dummy" then
+		minetest.remove_node(pos)
+		local pos1 = {x=pos.x, y=pos.y-1, z=pos.z}
+		node = minetest.get_node(pos1)
+		if node.name == "sl_robot:robot_foot" or node.name == "sl_robot:robot_leg" then
+			minetest.remove_node(pos1)
+			pos1 = {x=pos.x, y=pos.y-2, z=pos.z}
+			node = minetest.get_node(pos1)
+			if node.name == "sl_robot:robot_foot" then
+				minetest.remove_node(pos1)
+			end
+		end
+	end
+end
+
+-- Positions to check:
+--     3
+--  [R]1  
+--   4 2
+--   5 
+function sl_robot.move_robot(pos, param2, step)
+	local pos1 = sl_robot.new_pos(pos, param2, step)
+	local pos2 = {x=pos1.x, y=pos1.y-1, z=pos1.z}
+	local pos3 = {x=pos1.x, y=pos1.y+1, z=pos1.z}
+	local pos4 = {x=pos.x, y=pos.y-1, z=pos.z}
+	local pos5 = {x=pos.x, y=pos.y-2, z=pos.z}
+	local new_pos = nil
+	
+	if check_pos(pos1, pos2) then  -- one step forward
+		new_pos = pos1
+	elseif check_pos(pos3, pos1) then  -- one step up
+		new_pos = {x=pos.x, y=pos.y+1, z=pos.z}
+		minetest.swap_node(pos, {name="sl_robot:robot_foot"})
+		minetest.set_node(new_pos, {name="sl_robot:robot", param2=param2})
+		minetest.sound_play('sl_robot_step', {pos = new_pos})
+		return new_pos
+	elseif check_pos(pos1, pos4) then  -- one step forward
+		new_pos = pos1		
+	elseif check_pos(pos4, pos5) then  -- one step down
+		new_pos = pos4		
+	else
+		return nil -- blocked
+	end
+	local node4 = minetest.get_node(pos4)
+	if node4.name == "sl_robot:robot_foot" or node4.name == "sl_robot:robot_leg" then
+		minetest.remove_node(pos4)
+		local node5 = minetest.get_node(pos5)
+		if node5.name == "sl_robot:robot_foot" then
+			minetest.remove_node(pos5)
+		end
+	end
+	minetest.remove_node(pos)
+	minetest.set_node(new_pos, {name="sl_robot:robot", param2=param2})
+	minetest.sound_play('sl_robot_step', {pos = new_pos})
+	return new_pos
+end	
+	
+function sl_robot.turn_robot(pos, param2, dir)
+	if dir == "R" then
+		param2 = (param2 + 1) % 4
+	else
+		param2 = (param2 + 3) % 4
+	end
+	minetest.swap_node(pos, {name="sl_robot:robot", param2=param2})
+	minetest.sound_play('sl_robot_step', {pos = pos, gain = 0.6})
+	return param2
+end	
+
+-- Positions to check:
+--   1
+--  [R]  
+--   2
+function sl_robot.robot_up(pos, param2)
+	local pos1 = {x=pos.x, y=pos.y+1, z=pos.z}
+	local pos2 = {x=pos.x, y=pos.y-1, z=pos.z}
+	if check_pos(pos1, pos2) then
+		local node = minetest.get_node(pos2)
+		if node.name == "sl_robot:robot_foot" then 
+			minetest.swap_node(pos, {name="sl_robot:robot_leg"})
+		else
+			minetest.swap_node(pos, {name="sl_robot:robot_foot"})
+		end
+		minetest.set_node(pos1, {name="sl_robot:robot", param2=param2})
+		minetest.sound_play('sl_robot_step', {pos = new_pos})
+		return pos1
+	end
+	return nil
+end	
+
+-- Positions to check:
+--  [R]  
+--   1
+--   2
+function sl_robot.robot_down(pos, param2)
+	if dir == "U" then dir = 1 else dir = -1 end
+	local new_pos = {x=pos.x, y=pos.y-1, z=pos.z}
+	local new_pos_node = minetest.get_node(new_pos)
+	local objects = minetest.get_objects_inside_radius(new_pos, 1)
+	if #objects == 0 and new_pos_node.name == "sl_robot:robot_foot" or 
+				new_pos_node.name == "sl_robot:robot_leg" then
+		minetest.remove_node(pos)
+		minetest.set_node(new_pos, {name="sl_robot:robot", param2=param2})
+		minetest.sound_play('sl_robot_step', {pos = new_pos})
+		return new_pos
+	end
+	pos.y = pos.y+1
+	minetest.sound_play('sl_robot_go_away', {pos = pos, gain = 0.6})
+	pos.y = pos.y-1
+	return nil
+end	
+
+
+minetest.register_node("sl_robot:robot", {
+	description = "SaferLua Robot",
+	-- up, down, right, left, back, front
+	tiles = {
+		"sl_robot_robot_top.png",
+		"sl_robot_robot_bottom.png",
+		"sl_robot_robot_right.png",
+		"sl_robot_robot_left.png",
+		"sl_robot_robot_front.png",
+		"sl_robot_robot_back.png",
+		
+	},
+	drawtype = "nodebox",
+	node_box = {
+		type = "fixed",
+		fixed = {
+			{ -5/16,  3/16, -5/16,   5/16,  8/16, 5/16},
+			{ -3/16,  2/16, -3/16,   3/16,  3/16, 3/16},
+			{ -6/16, -7/16, -6/16,   6/16,  2/16, 6/16},
+			{ -6/16, -8/16, -3/16,   6/16, -7/16, 3/16},
+		},
+	},
+	paramtype2 = "facedir",
+	is_ground_content = false,
+	groups = {crumbly=0, not_in_creative_inventory = 1},
+	sounds = default.node_sound_metal_defaults(),
+})
+
+-- dummy robots are used as marker for stucked robots in unloaded areas
+minetest.register_node("sl_robot:robot_dummy", {
+	description = "SaferLua Robot",
+	-- up, down, right, left, back, front
+	tiles = {
+		"sl_robot_robot_top.png^[opacity:127",
+		"sl_robot_robot_bottom.png^[opacity:127",
+		"sl_robot_robot_right.png^[opacity:127",
+		"sl_robot_robot_left.png^[opacity:127",
+		"sl_robot_robot_front.png^[opacity:127",
+		"sl_robot_robot_back.png^[opacity:127",
+	},
+	drawtype = "nodebox",
+	use_texture_alpha = true,
+	node_box = {
+		type = "fixed",
+		fixed = {
+			{ -5/16,  3/16, -5/16,   5/16,  8/16, 5/16},
+			{ -3/16,  2/16, -3/16,   3/16,  3/16, 3/16},
+			{ -6/16, -7/16, -6/16,   6/16,  2/16, 6/16},
+			{ -6/16, -8/16, -3/16,   6/16, -7/16, 3/16},
+		},
+	},
+	paramtype2 = "facedir",
+	is_ground_content = false,
+	walkable = false,
+	drop = "",
+	groups = {cracky = 3},
+	sounds = default.node_sound_metal_defaults(),
+})
+
+minetest.register_node("sl_robot:robot_leg", {
+	description = "SaferLua Robot",
+	tiles = {"sl_robot_robot.png^[transformR90]"},
+	drawtype = "nodebox",
+	node_box = {
+		type = "fixed",
+		fixed = {
+			{ -1/8, -4/8, -1/8,   1/8, 4/8, 1/8},
+		},
+	},
+	paramtype2 = "facedir",
+	is_ground_content = false,
+	groups = {crumbly=0, not_in_creative_inventory = 1},
+	sounds = default.node_sound_metal_defaults(),
+})
+
+minetest.register_node("sl_robot:robot_foot", {
+	description = "SaferLua Robot",
+	tiles = {"sl_robot_robot.png^[transformR90]"},
+	drawtype = "nodebox",
+	node_box = {
+		type = "fixed",
+		fixed = {
+			{ -1/8, -4/8, -1/8,   1/8, 4/8, 1/8},
+			{ -2/8, -4/8, -2/8,   2/8, -3/8, 2/8},
+		},
+	},
+	paramtype2 = "facedir",
+	is_ground_content = false,
+	groups = {crumbly=0, not_in_creative_inventory = 1},
+	sounds = default.node_sound_metal_defaults(),
+})
+
+
+minetest.register_lbm({
+	label = "[sl_robot] Remove Robots",
+	name = "sl_robot:update",
+	nodenames = {"sl_robot:robot", "sl_robot:robot_leg", "sl_robot:robot_foot"},
+	run_at_every_load = true,
+	action = function(pos, node)
+		if node.name == "sl_robot:robot" then
+			minetest.swap_node(pos, {name="sl_robot:robot_dummy", param2 = node.param2})
+		else
+			minetest.remove_node(pos)
+		end
+	end
+})
+