first try

LICENSE.txt

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+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

README.txt

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+Tower Crane Mod
+===============
+
+
+
+Usage
+-----
+
+1) Place the crane base.
+   The crane arm will later be build in the same direction yoi are currently looking 
+
+2) Right-click the crane base node and set the crane dimensions in height and width (between 8 and 24).
+   The crane will be build according to the settings.
+
+3) Right-click the crane switch node to place the hook in front of the crane mast
+
+4) Enter the hook by right-clicking the hook
+
+5) "Fly" within the construction area (height, width) by means of the (default) controls
+   - Move mouse: Look around
+   - W, A, S, D: Move
+   - Space: move up
+   - Shift: move down
+
+6) Leave the hook by right-clicking the hook or right-clicking the crane switch node
+
+7) To destroy the crane, destroy the base node.
+
+

depends.txt

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+default

description.txt

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+The Tower Crane Mod forms a constrution area below the crane arm which gives the crane owner "fly privs".

init.lua

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+--[[
+
+    Tower Crane Mod
+    ===============
+
+    v0.01 by JoSt
+    
+    Copyright (C) 2017 Joachim Stolberg
+    LGPLv2.1+
+    See LICENSE.txt for more information
+
+    History:
+    2017-06-04  v0.01  first version
+]]--
+
+
+towercrane = {}
+
+--##################################################################################################
+--##  Tower Crane Hook
+--##################################################################################################
+local hook = {
+	physical = true, 
+	collisionbox = {-0.2, -0.2, -0.2, 0.2, 0.2, 0.2},
+	collide_with_objects = false,   
+	visual = "cube",
+    visual_size = {x=0.4, y=0.4},
+	textures = {
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+    },
+    groups = {cracky=1},
+    -- local variabels
+	driver = nil,
+    speed_forward=0,
+    speed_right=0,
+    speed_up=0,
+}
+----------------------------------------------------------------------------------------------------
+-- Enter/leave the Hook
+----------------------------------------------------------------------------------------------------
+function hook:on_rightclick(clicker)
+	if self.driver and clicker == self.driver then  -- leave?
+		clicker:set_detach()
+		self.driver = nil
+	elseif not self.driver then                     -- enter?
+		self.driver = clicker
+        clicker:set_attach(self.object, "", {x=0,y=0,z=0}, {x=0,y=0,z=0})
+	end
+end
+
+----------------------------------------------------------------------------------------------------
+-- Hook control
+----------------------------------------------------------------------------------------------------
+function hook:on_step(dtime)
+    -- remove hook from  last visit
+    if self.pos1 == nil or self.pos2 == nil then
+        self.object:remove()
+        return
+    end
+    if self.driver then
+        local ctrl = self.driver:get_player_control()
+        local yaw = self.driver:get_look_horizontal()
+        local pos = self.driver:getpos()
+        local max_speed = 5
+        local velocity = 0.5
+
+        if ctrl.up then             -- forward
+            self.speed_forward = math.min(self.speed_forward + velocity, max_speed)
+        elseif ctrl.down then       -- backward
+            self.speed_forward = math.max(self.speed_forward - velocity, -max_speed)
+        elseif self.speed_forward > 0 then
+            self.speed_forward = self.speed_forward - velocity
+        elseif self.speed_forward < 0 then
+            self.speed_forward = self.speed_forward + velocity
+        end
+        
+        if ctrl.right then          -- right
+            self.speed_right = math.min(self.speed_right + velocity, max_speed)
+        elseif ctrl.left then       -- left
+            self.speed_right = math.max(self.speed_right - velocity, -max_speed)
+        elseif self.speed_right > 0 then
+            self.speed_right = self.speed_right - velocity
+        elseif self.speed_right < 0 then
+            self.speed_right = self.speed_right + velocity
+        end
+
+        if ctrl.jump then           -- up
+            self.speed_up = math.min(self.speed_up + velocity, 5)
+        elseif ctrl.sneak then      -- down
+            self.speed_up = math.max(self.speed_up - velocity, -5)
+        elseif self.speed_up > 0 then
+            self.speed_up = self.speed_up - velocity
+        elseif self.speed_up < 0 then
+            self.speed_up = self.speed_up + velocity
+        end
+
+        -- calculate the direction vector
+        local vx = math.cos(yaw+math.pi/2) * self.speed_forward + math.cos(yaw) * self.speed_right
+        local vz = math.sin(yaw+math.pi/2) * self.speed_forward + math.sin(yaw) * self.speed_right
+
+        -- check if outside of the construction area
+        if pos.x < self.pos1.x then vx= velocity end
+        if pos.x > self.pos2.x then vx= -velocity end
+        if pos.y < self.pos1.y then self.speed_up=  velocity end
+        if pos.y > self.pos2.y then self.speed_up= -velocity end
+        if pos.z < self.pos1.z then vz=  velocity end
+        if pos.z > self.pos2.z then vz= -velocity end
+
+        self.object:setvelocity({x=vx, y=self.speed_up,z=vz})
+    else
+        self.object:setvelocity({x=0, y=0,z=0})
+    end
+end
+
+----------------------------------------------------------------------------------------------------
+-- LuaEntitySAO (non-player moving things): see http://dev.minetest.net/LuaEntitySAO
+----------------------------------------------------------------------------------------------------
+minetest.register_entity("towercrane:hook", hook)
+
+
+
+--##################################################################################################
+--##  Tower Crane
+--##################################################################################################
+
+local function turnright(dir)
+    local facedir = minetest.dir_to_facedir(dir)
+    return minetest.facedir_to_dir((facedir + 1) % 4)
+end
+
+local function turnleft(dir)
+    local facedir = minetest.dir_to_facedir(dir)
+    return minetest.facedir_to_dir((facedir + 3) % 4)
+end
+
+----------------------------------------------------------------------------------------------------
+-- Constuct mast and arm
+----------------------------------------------------------------------------------------------------
+local function construct_crane(pos, dir, height, width, owner)
+    pos.y = pos.y + 1
+    minetest.env:add_node(pos, {name="towercrane:mast_ctrl_off", param2=minetest.dir_to_facedir(dir)})
+    local meta = minetest.get_meta(pos)
+    meta:set_string("dir", minetest.pos_to_string(dir))
+    meta:set_string("owner", owner)
+    meta:set_int("height", height)
+    meta:set_int("width", width)
+
+    for i = 1,height+1 do
+        pos.y = pos.y + 1
+        minetest.env:add_node(pos, {name="towercrane:mast"})
+    end
+    
+    pos.y = pos.y - 2
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:add_node(pos, {name="towercrane:arm2"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:add_node(pos, {name="towercrane:arm"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:add_node(pos, {name="towercrane:balance"})
+    pos.x = pos.x + 3 * dir.x
+    pos.z = pos.z + 3 * dir.z
+    
+    for i = 1,width do
+        pos.x = pos.x + dir.x
+        pos.z = pos.z + dir.z
+        if i % 2 == 0 then
+            minetest.env:add_node(pos, {name="towercrane:arm2"})
+        else
+            minetest.env:add_node(pos, {name="towercrane:arm"})
+        end
+        
+    end
+end
+
+----------------------------------------------------------------------------------------------------
+-- Remove the crane
+----------------------------------------------------------------------------------------------------
+local function dig_crane(pos, dir, height, width)
+    pos.y = pos.y + 1
+    minetest.env:remove_node(pos, {name="towercrane:mast_ctrl_off"})
+    
+    for i = 1,height+1 do
+        pos.y = pos.y + 1
+        minetest.env:remove_node(pos, {name="towercrane:mast"})
+    end
+
+    pos.y = pos.y - 2
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:remove_node(pos, {name="towercrane:arm2"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:remove_node(pos, {name="towercrane:arm"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:remove_node(pos, {name="towercrane:balance"})
+    pos.x = pos.x + 3 * dir.x
+    pos.z = pos.z + 3 * dir.z
+    
+    for i = 1,width do
+        pos.x = pos.x + dir.x
+        pos.z = pos.z + dir.z
+        if i % 2 == 0 then
+            minetest.env:remove_node(pos, {name="towercrane:arm2"})
+        else
+            minetest.env:remove_node(pos, {name="towercrane:arm"})
+        end
+    end
+end
+
+----------------------------------------------------------------------------------------------------
+-- Place the hook in front of the base
+----------------------------------------------------------------------------------------------------
+local function place_hook(pos, dir)
+    pos.y = pos.y - 1
+    pos.x = pos.x + dir.x
+    pos.z = pos.z + dir.z
+    return minetest.add_entity(pos, "towercrane:hook")
+end
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane base
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:base", {
+    description = "Tower Crane Base",
+    inventory_image = "towercrane_invent.png",
+    tiles = {
+        "towercrane_base_top.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+    },
+    paramtype2 = "facedir",
+    is_ground_content = false,
+    groups = {cracky=3},
+    formspec = set_formspec,
+
+    -- set meta data (form for crane height and width, dir of the arm)
+    after_place_node = function(pos, placer)
+        local meta = minetest.get_meta(pos)
+        local owner = placer:get_player_name()
+        meta:set_string("owner", owner)
+        local formspec = "size[5,4]"..
+            "label[0,0;Construction area size]" ..
+            "field[1,1.5;3,1;size;height,width;]" ..
+            "button_exit[1,2;2,1;exit;Save]"
+        meta:set_string("formspec", formspec)
+
+        local fdir = minetest.dir_to_facedir(placer:get_look_dir(), false)
+        local dir = minetest.facedir_to_dir(fdir)
+        meta:set_string("dir", minetest.pos_to_string(dir))
+    end,
+
+    -- evaluate user input (height, width), destroyed old crane and build a new one with
+    -- the given size
+    on_receive_fields = function(pos, formname, fields, player)
+        if fields.size == nil then
+            return
+        end
+        local meta = minetest.get_meta(pos)
+
+        if not player or not player:is_player() then
+            return
+        end
+        local owner = meta:get_string("owner")
+        if player:get_player_name() ~= owner then
+            return
+        end
+        
+        local dir = minetest.string_to_pos(meta:get_string("dir"))
+        local height = meta:get_int("height")
+        local width = meta:get_int("width")
+        local org_pos = table.copy(pos)
+        if dir ~= nil and height ~= nil and width ~= nil then
+           dig_crane(pos, dir, height, width)
+        end
+        --check for correct size format
+        size = string.split(fields.size, ",")
+        if #size == 2  then
+            local height = tonumber(size[1])
+            local width = tonumber(size[2])
+            if height ~= nil and width ~= nil then
+                height = math.max(height, 8)
+                height = math.min(height, 24)
+                width = math.max(width, 8)
+                width = math.min(width, 24)
+                meta:set_int("height", height)
+                meta:set_int("width", width)
+                meta:set_string("infotext", "Crane size: " .. height .. "," .. width)
+                if dir ~= nil then
+                    construct_crane(org_pos, dir, height, width, owner)
+                end
+            end
+        end
+    end,
+
+    -- remove mast and arm if base gets destroyed
+    on_destruct = function(pos)
+        local meta = minetest.get_meta(pos)
+        local dir = minetest.string_to_pos(meta:get_string("dir"))
+        local height = meta:get_int("height")
+        local width = meta:get_int("width")
+
+        if dir ~= nil and height ~= nil and width ~= nil then
+           dig_crane(pos, dir, height, width)
+        end
+    end,
+})
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane balance
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:balance", {
+  description = "Tower Crane Balance",
+  tiles = {
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane mast
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:mast", {
+  description = "Tower Crane Mast",
+  drawtype = "glasslike_framed",
+  tiles = {
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane Switch (on)
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:mast_ctrl_on", {
+  description = "Tower Crane Mast Ctrl On",
+  drawtype = "node",
+  tiles = {
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl_on.png",
+      "towercrane_mast_ctrl_on.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+  },
+  on_rightclick = function (pos, node, clicker)
+    local meta = minetest.get_meta(pos)
+    if not clicker or not clicker:is_player() then
+        return
+    end
+    if clicker:get_player_name() ~= meta:get_string("owner") then
+        return
+    end
+    node.name = "towercrane:mast_ctrl_off"
+    minetest.swap_node(pos, node)
+
+    local id = minetest.hash_node_position(pos)
+    if towercrane.id then
+        towercrane.id:remove()
+        towercrane.id = nil
+    else
+    
+    end
+  end,
+  
+  on_construct = function(pos)
+    local meta = minetest.get_meta(pos)
+    meta:set_string("infotext", "Switch crane on/off")
+  end,
+  
+  after_place_node = function(pos, placer, itemstack, pointed_thing)
+    local meta = minetest.get_meta(pos)
+    local owner = placer:get_player_name()
+    meta:set_string("owner", owner)
+  end,
+  
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane Switch (off)
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:mast_ctrl_off", {
+  description = "Tower Crane Mast Ctrl Off",
+  drawtype = "node",
+  tiles = {
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl_off.png",
+      "towercrane_mast_ctrl_off.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+  },
+  on_rightclick = function (pos, node, clicker)
+    -- switch switch on, calculate the construction area, and place the hook
+    local meta = minetest.get_meta(pos)
+    -- only the owner is allowed to switch
+    if not clicker or not clicker:is_player() then
+        return
+    end
+    if clicker:get_player_name() ~= meta:get_string("owner") then
+        return
+    end
+    -- swap to the other node
+    node.name = "towercrane:mast_ctrl_on"
+    minetest.swap_node(pos, node)
+    local dir = minetest.string_to_pos(meta:get_string("dir"))
+    if pos ~= nil and dir ~= nil then
+        -- store hook instance in 'towercrane'
+        local id = minetest.hash_node_position(pos)
+        towercrane.id = place_hook(table.copy(pos), dir)
+
+        -- calculate the construction area dimension (pos, pos2)
+        local height = meta:get_int("height")
+        local width = meta:get_int("width")
+
+        -- pos1 = close/right
+        dir = turnright(dir)
+        local pos1 = vector.add(pos, vector.multiply(dir, width/2))
+        dir = turnleft(dir)
+        local pos1 = vector.add(pos1, vector.multiply(dir, 1))
+        pos1.y = pos.y - 1
+
+        -- pos2 = far/left
+        local pos2 = vector.add(pos1, vector.multiply(dir, width-1))
+        dir = turnleft(dir)
+        pos2 = vector.add(pos2, vector.multiply(dir, width))
+        pos2.y = pos.y - 4 + height
+
+        -- normalize x/z so that pos2 > pos1
+        if pos2.x < pos1.x then
+            pos2.x, pos1.x = pos1.x, pos2.x
+        end
+        if pos2.z < pos1.z then
+            pos2.z, pos1.z = pos1.z, pos2.z
+        end
+
+        -- store pos1/pos2 in the hook (LuaEntitySAO)
+        towercrane.id:get_luaentity().pos1 = pos1
+        towercrane.id:get_luaentity().pos2 = pos2
+    end
+  end,
+
+  on_construct = function(pos)
+    -- add infotext
+    local meta = minetest.get_meta(pos)
+    meta:set_string("infotext", "Switch crane on/off")
+  end,
+
+  after_place_node = function(pos, placer, itemstack, pointed_thing)
+    -- store owner for dig protection
+    local meta = minetest.get_meta(pos)
+    local owner = placer:get_player_name()
+    meta:set_string("owner", owner)
+  end,
+  
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane arm 1
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:arm", {
+  description = "Tower Crane Arm",
+  drawtype = "glasslike_framed",
+  tiles = {
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+----------------------------------------------------------------------------------------------------
+-- Register Crane arm 2
+----------------------------------------------------------------------------------------------------
+minetest.register_node("towercrane:arm2", {
+  description = "Tower Crane Arm2",
+  drawtype = "glasslike_framed",
+  tiles = {
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})

init.lua.org

@@ -0,0 +1,483 @@
+--[[
+
+    Tower Crane (Liebherr) Mod
+    by JoSt
+    
+    Copyright (C) 2017 Joachim Stolberg
+    LGPLv2.1+
+    See LICENSE for more information
+
+]]--
+
+
+towercrane = {}
+
+local hook = {
+	physical = true, -- should be true, otherwise you dive into the underground
+	collisionbox = {-0.2, -0.2, -0.2, 0.2, 0.2, 0.2}, -- Groesse des Wuerfels bei Kollisionen
+	collide_with_objects = false,   
+	visual = "cube",                    -- Object als Wuerfel
+    visual_size = {x=0.4, y=0.4},       -- Groesse des sichtbaren Wuerfels
+	textures = {
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+        "towercrane_hook.png",
+    },
+    groups = {cracky=1},
+    -- local variabels
+	driver = nil,
+    speed_forward=0,
+    speed_right=0,
+    speed_up=0,
+}
+
+-- ":" methode von "hook" (self ist versteckt)
+function hook:on_rightclick(clicker)
+	if self.driver and clicker == self.driver then  -- aussteigen?
+		clicker:set_detach()
+		self.driver = nil
+	elseif not self.driver then                     -- einsteigen?
+		self.driver = clicker
+        clicker:set_attach(self.object, "", {x=0,y=0,z=0}, {x=0,y=0,z=0})
+	end
+end
+
+function hook:on_step(dtime)
+    -- remove hook from  last visit
+    if self.pos1 == nil or self.pos2 == nil then
+        self.object:remove()
+        return
+    end
+    if self.driver then
+        local ctrl = self.driver:get_player_control()
+        local yaw = self.driver:get_look_horizontal()
+        local pos = self.driver:getpos()
+        local max_speed = 5
+        local velocity = 0.5
+
+        if ctrl.up then             -- forward
+            self.speed_forward = math.min(self.speed_forward + velocity, max_speed)
+        elseif ctrl.down then       -- backward
+            self.speed_forward = math.max(self.speed_forward - velocity, -max_speed)
+        elseif self.speed_forward > 0 then
+            self.speed_forward = self.speed_forward - velocity
+        elseif self.speed_forward < 0 then
+            self.speed_forward = self.speed_forward + velocity
+        end
+        
+        if ctrl.right then          -- right
+            self.speed_right = math.min(self.speed_right + velocity, max_speed)
+        elseif ctrl.left then       -- left
+            self.speed_right = math.max(self.speed_right - velocity, -max_speed)
+        elseif self.speed_right > 0 then
+            self.speed_right = self.speed_right - velocity
+        elseif self.speed_right < 0 then
+            self.speed_right = self.speed_right + velocity
+        end
+
+        if ctrl.jump then           -- up
+            self.speed_up = math.min(self.speed_up + velocity, 5)
+        elseif ctrl.sneak then      -- down
+            self.speed_up = math.max(self.speed_up - velocity, -5)
+        elseif self.speed_up > 0 then
+            self.speed_up = self.speed_up - velocity
+        elseif self.speed_up < 0 then
+            self.speed_up = self.speed_up + velocity
+        end
+
+        -- calculate the direction vector
+        local vx = math.cos(yaw+math.pi/2) * self.speed_forward + math.cos(yaw) * self.speed_right
+        local vz = math.sin(yaw+math.pi/2) * self.speed_forward + math.sin(yaw) * self.speed_right
+
+        -- check if outside of the construction area
+        if pos.x < self.pos1.x then vx= velocity end
+        if pos.x > self.pos2.x then vx= -velocity end
+        if pos.y < self.pos1.y then self.speed_up=  velocity end
+        if pos.y > self.pos2.y then self.speed_up= -velocity end
+        if pos.z < self.pos1.z then vz=  velocity end
+        if pos.z > self.pos2.z then vz= -velocity end
+
+        self.object:setvelocity({x=vx, y=self.speed_up,z=vz})
+    else
+        self.object:setvelocity({x=0, y=0,z=0})
+    end
+end
+
+-- LuaEntitySAO (non-player moving things): see http://dev.minetest.net/LuaEntitySAO
+minetest.register_entity("towercrane:hook", hook)
+
+----------------------------------------------------------------------------------------------------
+----------------------------------------------------------------------------------------------------
+----------------------------------------------------------------------------------------------------
+local function turnright(dir)
+    local facedir = minetest.dir_to_facedir(dir)
+    return minetest.facedir_to_dir((facedir + 1) % 4)
+end
+
+local function turnleft(dir)
+    local facedir = minetest.dir_to_facedir(dir)
+    return minetest.facedir_to_dir((facedir + 3) % 4)
+end
+
+local function construct_crane(pos, dir, height, width, owner)
+    pos.y = pos.y + 1
+    minetest.env:add_node(pos, {name="towercrane:mast_ctrl_off", param2=minetest.dir_to_facedir(dir)})
+    local meta = minetest.get_meta(pos)
+    meta:set_string("dir", minetest.pos_to_string(dir))
+    meta:set_string("owner", owner)
+    meta:set_int("height", height)
+    meta:set_int("width", width)
+
+    for i = 1,height+1 do
+        pos.y = pos.y + 1
+        minetest.env:add_node(pos, {name="towercrane:mast"})
+    end
+    
+    pos.y = pos.y - 2
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:add_node(pos, {name="towercrane:arm2"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:add_node(pos, {name="towercrane:arm"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:add_node(pos, {name="towercrane:balance"})
+    pos.x = pos.x + 3 * dir.x
+    pos.z = pos.z + 3 * dir.z
+    
+    for i = 1,width do
+        pos.x = pos.x + dir.x
+        pos.z = pos.z + dir.z
+        if i % 2 == 0 then
+            minetest.env:add_node(pos, {name="towercrane:arm2"})
+        else
+            minetest.env:add_node(pos, {name="towercrane:arm"})
+        end
+        
+    end
+end
+
+local function dig_crane(pos, dir, height, width)
+    pos.y = pos.y + 1
+    minetest.env:remove_node(pos, {name="towercrane:mast_ctrl_off"})
+    
+    for i = 1,height+1 do
+        pos.y = pos.y + 1
+        minetest.env:remove_node(pos, {name="towercrane:mast"})
+    end
+
+    pos.y = pos.y - 2
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:remove_node(pos, {name="towercrane:arm2"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:remove_node(pos, {name="towercrane:arm"})
+    pos.x = pos.x - dir.x
+    pos.z = pos.z - dir.z
+    minetest.env:remove_node(pos, {name="towercrane:balance"})
+    pos.x = pos.x + 3 * dir.x
+    pos.z = pos.z + 3 * dir.z
+    
+    for i = 1,width do
+        pos.x = pos.x + dir.x
+        pos.z = pos.z + dir.z
+        if i % 2 == 0 then
+            minetest.env:remove_node(pos, {name="towercrane:arm2"})
+        else
+            minetest.env:remove_node(pos, {name="towercrane:arm"})
+        end
+        
+    end
+end
+
+local function place_hook(pos, dir)
+    pos.y = pos.y - 1
+    pos.x = pos.x + dir.x
+    pos.z = pos.z + dir.z
+    return minetest.add_entity(pos, "towercrane:hook")
+end
+
+minetest.register_node("towercrane:base", {
+    description = "Tower Crane Base",
+    inventory_image = "towercrane_invent.png",
+    tiles = {
+        "towercrane_base_top.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+        "towercrane_base.png",
+    },
+    paramtype2 = "facedir",
+    is_ground_content = false,
+    groups = {cracky=1},
+    formspec = set_formspec,
+
+
+    after_place_node = function(pos, placer)
+        local meta = minetest.get_meta(pos)
+        local owner = placer:get_player_name()
+        meta:set_string("owner", owner)
+        local formspec = "size[5,4]"..
+            "label[0,0;Construction area size]" ..
+            "field[1,1.5;3,1;size;height,width;]" ..
+            "button_exit[1,2;2,1;exit;Save]"
+        meta:set_string("formspec", formspec)
+
+        local fdir = minetest.dir_to_facedir(placer:get_look_dir(), false)
+        local dir = minetest.facedir_to_dir(fdir)
+        meta:set_string("dir", minetest.pos_to_string(dir))
+    end,
+
+    on_receive_fields = function(pos, formname, fields, player)
+        if fields.size == nil then
+            return
+        end
+        local meta = minetest.get_meta(pos)
+
+        if not player or not player:is_player() then
+            return
+        end
+        local owner = meta:get_string("owner")
+        if player:get_player_name() ~= owner then
+            return
+        end
+        
+        local dir = minetest.string_to_pos(meta:get_string("dir"))
+        local height = meta:get_int("height")
+        local width = meta:get_int("width")
+        local org_pos = table.copy(pos)
+        if dir ~= nil and height ~= nil and width ~= nil then
+           dig_crane(pos, dir, height, width)
+        end
+        --check for correct size format
+        size = string.split(fields.size, ",")
+        if #size == 2  then
+            local height = tonumber(size[1])
+            local width = tonumber(size[2])
+            if height ~= nil and width ~= nil then
+                height = math.max(height, 8)
+                height = math.min(height, 24)
+                width = math.max(width, 8)
+                width = math.min(width, 24)
+                meta:set_int("height", height)
+                meta:set_int("width", width)
+                meta:set_string("infotext", "Crane size: " .. height .. "," .. width)
+                if dir ~= nil then
+                    construct_crane(org_pos, dir, height, width, owner)
+                end
+            end
+        end
+    end,
+    
+    on_destruct = function(pos)
+        local meta = minetest.get_meta(pos)
+        local dir = minetest.string_to_pos(meta:get_string("dir"))
+        local height = meta:get_int("height")
+        local width = meta:get_int("width")
+
+        if dir ~= nil and height ~= nil and width ~= nil then
+           dig_crane(pos, dir, height, width)
+        end
+    end,
+})
+
+minetest.register_on_leaveplayer(function(ObjectRef, timed_out)
+    print("Schade")
+  end
+)
+
+
+minetest.register_node("towercrane:balance", {
+  description = "Tower Crane Balance",
+  tiles = {
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+      "towercrane_base.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+minetest.register_node("towercrane:mast", {
+  description = "Tower Crane Mast",
+  drawtype = "glasslike_framed",
+  tiles = {
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+      "towercrane_mast.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+minetest.register_node("towercrane:mast_ctrl_on", {
+  description = "Tower Crane Mast Ctrl On",
+  drawtype = "node",
+  tiles = {
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl_on.png",
+      "towercrane_mast_ctrl_on.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+  },
+  on_rightclick = function (pos, node, clicker)
+    local meta = minetest.get_meta(pos)
+    if not clicker or not clicker:is_player() then
+        return
+    end
+    if clicker:get_player_name() ~= meta:get_string("owner") then
+        return
+    end
+    node.name = "towercrane:mast_ctrl_off"
+    minetest.swap_node(pos, node)
+
+    local id = minetest.hash_node_position(pos)
+    if towercrane.id then
+        towercrane.id:remove()
+        towercrane.id = nil
+    else
+    
+    end
+  end,
+  
+  on_construct = function(pos)
+    local meta = minetest.get_meta(pos)
+    meta:set_string("infotext", "Switch crane on/off")
+  end,
+  
+  after_place_node = function(pos, placer, itemstack, pointed_thing)
+    local meta = minetest.get_meta(pos)
+    local owner = placer:get_player_name()
+    meta:set_string("owner", owner)
+  end,
+  
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+minetest.register_node("towercrane:mast_ctrl_off", {
+  description = "Tower Crane Mast Ctrl Off",
+  drawtype = "node",
+  tiles = {
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl_off.png",
+      "towercrane_mast_ctrl_off.png",
+      "towercrane_mast_ctrl.png",
+      "towercrane_mast_ctrl.png",
+  },
+  on_rightclick = function (pos, node, clicker)
+    -- switch switch on, calculate the construction area, and place the hook
+    local meta = minetest.get_meta(pos)
+    -- only the owner is allowed to switch
+    if not clicker or not clicker:is_player() then
+        return
+    end
+    if clicker:get_player_name() ~= meta:get_string("owner") then
+        return
+    end
+    -- swap to the other node
+    node.name = "towercrane:mast_ctrl_on"
+    minetest.swap_node(pos, node)
+    local dir = minetest.string_to_pos(meta:get_string("dir"))
+    if pos ~= nil and dir ~= nil then
+        -- store hook instance in 'towercrane'
+        local id = minetest.hash_node_position(pos)
+        towercrane.id = place_hook(table.copy(pos), dir)
+
+        -- calculate the construction area dimension (pos, pos2)
+        local height = meta:get_int("height")
+        local width = meta:get_int("width")
+
+        -- pos1 = close/right
+        dir = turnright(dir)
+        local pos1 = vector.add(pos, vector.multiply(dir, width/2))
+        dir = turnleft(dir)
+        local pos1 = vector.add(pos1, vector.multiply(dir, 1))
+        pos1.y = pos.y - 1
+
+        -- pos2 = far/left
+        local pos2 = vector.add(pos1, vector.multiply(dir, width-1))
+        dir = turnleft(dir)
+        pos2 = vector.add(pos2, vector.multiply(dir, width))
+        pos2.y = pos.y - 4 + height
+
+        -- normalize x/z so that pos2 > pos1
+        if pos2.x < pos1.x then
+            pos2.x, pos1.x = pos1.x, pos2.x
+        end
+        if pos2.z < pos1.z then
+            pos2.z, pos1.z = pos1.z, pos2.z
+        end
+
+        -- store pos1/pos2 in the hook (LuaEntitySAO)
+        towercrane.id:get_luaentity().pos1 = pos1
+        towercrane.id:get_luaentity().pos2 = pos2
+    end
+  end,
+
+  on_construct = function(pos)
+    -- add infotext
+    local meta = minetest.get_meta(pos)
+    meta:set_string("infotext", "Switch crane on/off")
+  end,
+
+  after_place_node = function(pos, placer, itemstack, pointed_thing)
+    -- store owner for dig protection
+    local meta = minetest.get_meta(pos)
+    local owner = placer:get_player_name()
+    meta:set_string("owner", owner)
+  end,
+  
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+minetest.register_node("towercrane:arm", {
+  description = "Tower Crane Arm",
+  drawtype = "glasslike_framed",
+  tiles = {
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+      "towercrane_arm.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})
+
+minetest.register_node("towercrane:arm2", {
+  description = "Tower Crane Arm2",
+  drawtype = "glasslike_framed",
+  tiles = {
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+      "towercrane_arm2.png",
+  },
+  paramtype2 = "facedir",
+  is_ground_content = false,
+  groups = {crumbly=0, not_in_creative_inventory=1},
+})