digtron.get_all_digtron_neighbours = function(pos, player)
	-- returns table containing a list of all digtron node locations, lists of special digtron node types, a table of the coordinate extents of the digtron array, a Pointset of protected nodes, and a number to determine how many adjacent solid non-digtron nodes there are (for traction)
	
	local layout = {}
	--initialize. We're assuming that the start position is a controller digtron, should be a safe assumption since only the controller node should call this
	layout.traction = 0
	layout.all = {}
	layout.inventories = {}
	layout.fuelstores = {}
	layout.diggers = {}
	layout.builders = {}
	layout.extents = {}
	layout.water_touching = false
	layout.lava_touching = false
	layout.protected = Pointset.create() -- if any nodes we look at are protected, make note of that. That way we don't need to keep re-testing protection state later.
	layout.controller = {x=pos.x, y=pos.y, z=pos.z} 	--Make a deep copy of the pos parameter just in case the calling code wants to play silly buggers with it

	table.insert(layout.all, layout.controller)
	layout.extents.max_x = pos.x
	layout.extents.min_x = pos.x
	layout.extents.max_y = pos.y
	layout.extents.min_y = pos.y
	layout.extents.max_z = pos.z
	layout.extents.min_z = pos.z
	
	-- temporary pointsets used while searching
	local to_test = Pointset.create()
	local tested = Pointset.create()

	tested:set(pos.x, pos.y, pos.z, true)
	to_test:set(pos.x + 1, pos.y, pos.z, true)
	to_test:set(pos.x - 1, pos.y, pos.z, true)
	to_test:set(pos.x, pos.y + 1, pos.z, true)
	to_test:set(pos.x, pos.y - 1, pos.z, true)
	to_test:set(pos.x, pos.y, pos.z + 1, true)
	to_test:set(pos.x, pos.y, pos.z - 1, true)
	
	if minetest.is_protected(pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
		layout.protected:set(pos.x, pos.y, pos.z, true)
	end
	
	-- Do a loop on to_test positions, adding new to_test positions as we find digtron nodes. This is a flood fill operation
	-- that follows node faces (no diagonals)
	local testpos, _ = to_test:pop()
	while testpos ~= nil do
		tested:set(testpos.x, testpos.y, testpos.z, true) -- track nodes we've looked at to prevent infinite loops
		local node = minetest.get_node(testpos)

		if node.name == "ignore" then
			--buildtron array is next to unloaded nodes, too dangerous to do anything. Abort.
			layout.all = nil
			return layout
		end

		if minetest.is_protected(pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
			layout.protected:set(testpos.x, testpos.y, testpos.z, true)
		end
		
		if minetest.get_item_group(node.name, "water") ~= 0 then
			layout.water_touching = true
		elseif minetest.get_item_group(node.name, "lava") ~= 0 then
			layout.lava_touching = true
			if digtron.lava_impassible == true then
				layout.protected:set(testpos.x, testpos.y, testpos.z, true)
			end
		end
		
		local group_number = minetest.get_item_group(node.name, "digtron")
		if group_number > 0 then
			--found one. Add it to the digtrons output
			table.insert(layout.all, testpos)
		
			-- update extents
			layout.extents.max_x = math.max(layout.extents.max_x, testpos.x)
			layout.extents.min_x = math.min(layout.extents.min_x, testpos.x)
			layout.extents.max_y = math.max(layout.extents.max_y, testpos.y)
			layout.extents.min_y = math.min(layout.extents.min_y, testpos.y)
			layout.extents.max_z = math.max(layout.extents.max_z, testpos.z)
			layout.extents.min_z = math.min(layout.extents.min_z, testpos.z)
			
			-- add a reference to this node's position to special node lists
			if group_number == 2 then
				table.insert(layout.inventories, testpos)
			elseif group_number == 3 then
				table.insert(layout.diggers, testpos)
			elseif group_number == 4 then
				table.insert(layout.builders, testpos)
			elseif group_number == 5 then
				table.insert(layout.fuelstores, testpos)
			elseif group_number == 6 then
				table.insert(layout.inventories, testpos)
				table.insert(layout.fuelstores, testpos)
			end
			
			--queue up potential new test points adjacent to this digtron node
			to_test:set_if_not_in(tested, testpos.x + 1, testpos.y, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x - 1, testpos.y, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y + 1, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y - 1, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y, testpos.z + 1, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y, testpos.z - 1, true)
		elseif minetest.registered_nodes[node.name].buildable_to ~= true then
			-- Tracks whether the digtron is hovering in mid-air. If any part of the digtron array touches something solid it gains traction.
			layout.traction = layout.traction + 1
		end
		
		testpos, _ = to_test:pop()
	end
			
	return layout
end

-- Rotation magic
--------------------------------------------------------------------------------------------------------

local facedir_rotate = {
	['x'] = {
		[-1] = {[0]=4, 5, 6, 7, 22, 23, 20, 21, 0, 1, 2, 3, 13, 14, 15, 12, 19, 16, 17, 18, 10, 11, 8, 9}, -- 270 degrees
		[1] = {[0]=8, 9, 10, 11, 0, 1, 2, 3, 22, 23, 20, 21, 15, 12, 13, 14, 17, 18, 19, 16, 6, 7, 4, 5}, -- 90 degrees
	},
	['y'] = {
		[-1] = {[0]=3, 0, 1, 2, 19, 16, 17, 18, 15, 12, 13, 14, 7, 4, 5, 6, 11, 8, 9, 10, 21, 22, 23, 20}, -- 270 degrees
		[1] = {[0]=1, 2, 3, 0, 13, 14, 15, 12, 17, 18, 19, 16, 9, 10, 11, 8, 5, 6, 7, 4, 23, 20, 21, 22}, -- 90 degrees
	},
	['z'] = {
		[-1] = {[0]=16, 17, 18, 19, 5, 6, 7, 4, 11, 8, 9, 10, 0, 1, 2, 3, 20, 21, 22, 23, 12, 13, 14, 15}, -- 270 degrees
		[1] = {[0]=12, 13, 14, 15, 7, 4, 5, 6, 9, 10, 11, 8, 20, 21, 22, 23, 0, 1, 2, 3, 16, 17, 18, 19}, -- 90 degrees
	}
}

local wallmounted_rotate = {
	['x'] = {
		[-1] = {[0]=4, 5, 2, 3, 1, 0}, -- 270 degrees
		[1] = {[0]=5, 4, 2, 3, 0, 1}, -- 90 degrees
	},
	['y'] = {
		[-1] = {[0]=0, 1, 4, 5, 3, 2}, -- 270 degrees
		[1] = {[0]=0, 1, 5, 4, 2, 3}, -- 90 degrees
	},
	['z'] = {
		[-1] = {[0]=3, 2, 0, 1, 4, 5}, -- 270 degrees
		[1] = {[0]=2, 3, 1, 0, 4, 5}, -- 90 degrees
	}
}

	--90 degrees CW about x-axis: (x, y, z) -> (x, -z, y)
	--90 degrees CCW about x-axis: (x, y, z) -> (x, z, -y)
	--90 degrees CW about y-axis: (x, y, z) -> (-z, y, x)
	--90 degrees CCW about y-axis: (x, y, z) -> (z, y, -x)
	--90 degrees CW about z-axis: (x, y, z) -> (y, -x, z)
	--90 degrees CCW about z-axis: (x, y, z) -> (-y, x, z)
local rotate_pos = function(axis, direction, pos)
	if axis == "x" then
		if direction < 0 then
			return {x= pos.x, y= -pos.z, z= pos.y}
		else
			return {x= pos.x, y= pos.z, z= -pos.y}
		end
	elseif axis == "y" then
		if direction < 0 then
			return {x= -pos.z, y= pos.y, z= pos.x}
		else
			return {x= pos.z, y= pos.y, z= -pos.x}
		end
	else	
		if direction < 0 then
			return {x= -pos.y, y= pos.x, z= pos.z}
		else
			return {x= pos.y, y= -pos.x, z= pos.z}
		end
	end
end

local get_node_image = function(pos, node)
	local node_image = {node=node, pos={x=pos.x, y=pos.y, z=pos.z}}
	node_image.paramtype2 = minetest.registered_nodes[node.name].paramtype2
	local meta = minetest.get_meta(pos)
	node_image.meta = meta:to_table()
	
	-- Record what kind of thing we've got in a builder node so its facing can be rotated properly
	if minetest.get_item_group(node.name, "digtron") == 4 then
		local build_item = node_image.meta.inventory.main[1]
		if build_item ~= "" then
			local build_item_def = minetest.registered_nodes[ItemStack(build_item):get_name()]
			node_image.build_item_paramtype2 = build_item_def.paramtype2
		end
	end
	return node_image
end

local rotate_node_image = function(node_image, origin, axis, direction, old_pos_pointset)
	-- Facings
	if node_image.paramtype2 == "wallmounted" then
		node_image.node.param2 = wallmounted_rotate[axis][direction][node_image.node.param2]
	elseif node_image.paramtype2 == "facedir" then
		node_image.node.param2 = facedir_rotate[axis][direction][node_image.node.param2]
	end
	
	if node_image.build_item_paramtype2 == "wallmounted" then
		node_image.meta.fields.build_facing = wallmounted_rotate[axis][direction][node_image.meta.fields.build_facing]
	elseif node_image.build_item_paramtype2 == "facedir" then
		node_image.meta.fields.build_facing = facedir_rotate[axis][direction][node_image.meta.fields.build_facing]
	end
	
	node_image.meta.fields.waiting = nil -- If we're rotating a controller that's in the "waiting" state, clear it. Otherwise it may stick like that.

	-- record the old location so we can destroy the old node if the rotation operation is possible
	old_pos_pointset:set(node_image.pos.x, node_image.pos.y, node_image.pos.z, true)
	
	-- position in space relative to origin
	local pos = vector.subtract(node_image.pos, origin)
	pos = rotate_pos(axis, direction, pos)
	-- Move back to original reference frame
	node_image.pos = vector.add(pos, origin)
	
	return node_image	
end

digtron.rotate_layout_image = function(layout_image, facedir)
	-- To convert this into the direction the "top" of the axel node is pointing in:
	-- 0, 1, 2, 3 == (0,1,0)
	-- 4, 5, 6, 7 == (0,0,1)
	-- 8, 9, 10, 11 == (0,0,-1)
	-- 12, 13, 14, 15 == (1,0,0)
	-- 16, 17, 18, 19 == (-1,0,0)
	-- 20, 21, 22, 23== (0,-1,0)
	
	local top = {
		[0]={axis="y", dir=-1},
		{axis="z", dir=1},
		{axis="z", dir=-1},
		{axis="x", dir=1},
		{axis="x", dir=-1},
		{axis="y", dir=1},
	}
	local params = top[math.floor(facedir/4)]

	layout_image.old_pos_pointset = Pointset:create()
	
	for k, node_image in pairs(layout_image.all) do
		rotate_node_image(node_image, layout_image.controller, params.axis, params.dir, layout_image.old_pos_pointset)
	end
	return layout_image
end

digtron.can_write_layout_image = function(layout_image, player)
	for k, node_image in pairs(layout_image.all) do
		if not layout_image.old_pos_pointset:get(node_image.pos.x, node_image.pos.y, node_image.pos.z)
			and not minetest.registered_nodes[minetest.get_node(node_image.pos).name].buildable_to then
			return false
		elseif minetest.is_protected(node_image.pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
			return false
		end
	end
	return true
end

digtron.write_layout_image = function(layout_image)
	-- destroy the old digtron
	local oldpos, _ = layout_image.old_pos_pointset:pop()
	while oldpos ~= nil do
		local old_def = minetest.registered_nodes[minetest.get_node(oldpos).name]
		minetest.remove_node(oldpos)		
		if old_def.after_dig_node ~= nil then
			old_def.after_dig_node(oldpos)
		end
		oldpos, _ = layout_image.old_pos_pointset:pop()
	end		

	-- create the new one
	for k, node_image in pairs(layout_image.all) do
		minetest.add_node(node_image.pos, node_image.node)
		minetest.get_meta(node_image.pos):from_table(node_image.meta)	

		local new_def = minetest.registered_nodes[node_image.node.name]
		if new_def.after_place_node ~= nil then
			new_def.after_place_node(node_image.pos)
		end
	end
end

-- Similar to get_layout, but far more comprehensive. This produces a data structure plus a set of temporary inventories that will allow the digtron to be rotated and then recreated.
digtron.get_layout_image = function(pos, player)

	local image = {}
	--initialize. We're assuming that the start position is a controller digtron, should be a safe assumption since only the controller node should call this
	image.all = {}
	image.extents = {}
	image.controller = {x=pos.x, y=pos.y, z=pos.z} 	--Make a deep copy of the pos parameter just in case the calling code wants to play silly buggers with it
	image.contains_protected_node = false -- used to indicate if at least one node in this digtron array is protected from the player.
	
	table.insert(image.all, get_node_image(pos, minetest.get_node(pos)))

	image.extents.max_x = pos.x
	image.extents.min_x = pos.x
	image.extents.max_y = pos.y
	image.extents.min_y = pos.y
	image.extents.max_z = pos.z
	image.extents.min_z = pos.z
	
	-- temporary pointsets used while searching
	local to_test = Pointset.create()
	local tested = Pointset.create()

	tested:set(pos.x, pos.y, pos.z, true)
	to_test:set(pos.x + 1, pos.y, pos.z, true)
	to_test:set(pos.x - 1, pos.y, pos.z, true)
	to_test:set(pos.x, pos.y + 1, pos.z, true)
	to_test:set(pos.x, pos.y - 1, pos.z, true)
	to_test:set(pos.x, pos.y, pos.z + 1, true)
	to_test:set(pos.x, pos.y, pos.z - 1, true)
	
	if minetest.is_protected(pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
		image.contains_protected_node = true
	end
	
	-- Do a loop on to_test positions, adding new to_test positions as we find digtron nodes. This is a flood fill operation
	-- that follows node faces (no diagonals)
	local testpos, _ = to_test:pop()
	while testpos ~= nil do
		tested:set(testpos.x, testpos.y, testpos.z, true) -- track nodes we've looked at to prevent infinite loops
		local node = minetest.get_node(testpos)

		if node.name == "ignore" then
			--buildtron array is next to unloaded nodes, too dangerous to do anything. Abort.
			return nil
		end
		
		local group_number = minetest.get_item_group(node.name, "digtron")
		if group_number > 0 then
			--found one. Add it to the digtrons output
			table.insert(image.all, get_node_image(testpos, node))

			if minetest.is_protected(pos, player:get_player_name()) and not minetest.check_player_privs(player, "protection_bypass") then
				image.contains_protected_node = true
			end
			
			-- update extents
			image.extents.max_x = math.max(image.extents.max_x, testpos.x)
			image.extents.min_x = math.min(image.extents.min_x, testpos.x)
			image.extents.max_y = math.max(image.extents.max_y, testpos.y)
			image.extents.min_y = math.min(image.extents.min_y, testpos.y)
			image.extents.max_z = math.max(image.extents.max_z, testpos.z)
			image.extents.min_z = math.min(image.extents.min_z, testpos.z)
			
			--queue up potential new test points adjacent to this digtron node
			to_test:set_if_not_in(tested, testpos.x + 1, testpos.y, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x - 1, testpos.y, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y + 1, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y - 1, testpos.z, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y, testpos.z + 1, true)
			to_test:set_if_not_in(tested, testpos.x, testpos.y, testpos.z - 1, true)
		end
		
		testpos, _ = to_test:pop()
	end
			
	return image
end