rewrote autoplacement code to make it more aware of filters,

autocrafter, nodebreaker, deployer, and made sure each item will only
initiate a connection to those sides which can accept such.  Fixed
various autorouting bugs as I ran across them.  Autorouting for various
devices is now:

filters: left and right sides only
nodebreaker, deployer:  back only
autocrafter:  all six sides
chests:  top, bottom, left, right, back (not front)
furnace: bottom, left, right, back (not the top or front)

autocrafter.lua

@@ -71,11 +71,15 @@ minetest.register_node("pipeworks:autocrafter",{
 		local meta = minetest.env:get_meta(pos);
 		local inv = meta:get_inventory()
 		return (inv:is_empty("src") and inv:is_empty("recipe") and inv:is_empty("dst"))
-	end})
+	end,
+	after_place_node = tube_scanforobjects,
+	after_dig_node = tube_scanforobjects,
+})
 
 minetest.register_abm({nodenames={"pipeworks:autocrafter"},interval=1,chance=1,
 			action=function(pos,node)
 				local meta=minetest.env:get_meta(pos)
 				local inv=meta:get_inventory()
 				autocraft(inv)
-			end})
+			end
+})

autoplace.lua

@@ -32,6 +32,8 @@ end
 -- autorouting for pneumatic tubes
 
 function tube_scanforobjects(pos)
+	if pos == nil then return end
+	print("tubes_scanforobjects called at pos "..dump(pos))
 	tube_autoroute({ x=pos.x-1, y=pos.y  , z=pos.z   })
 	tube_autoroute({ x=pos.x+1, y=pos.y  , z=pos.z   })
 	tube_autoroute({ x=pos.x  , y=pos.y-1, z=pos.z   })
@@ -53,37 +55,187 @@ function is_tube(nodename)
 end
 
 function tube_autoroute(pos)
-	nctr = minetest.env:get_node(pos)
+	local pxm=0
-	--print ("minetest.get_item_group("..nctr.name..',"tubedevice") == '..minetest.get_item_group(nctr.name, "tubedevice"))
+	local pxp=0
-	if (is_tube(nctr.name) == nil)
+	local pym=0
-		and minetest.get_item_group(nctr.name, "tubedevice") ~= 1 then return end
+	local pyp=0
+	local pzm=0
+	local pzp=0
 
-	pxm=0
+	local nxm = minetest.env:get_node({ x=pos.x-1, y=pos.y  , z=pos.z   })
-	pxp=0
+	local nxp = minetest.env:get_node({ x=pos.x+1, y=pos.y  , z=pos.z   })
-	pym=0
+	local nym = minetest.env:get_node({ x=pos.x  , y=pos.y-1, z=pos.z   })
-	pyp=0
+	local nyp = minetest.env:get_node({ x=pos.x  , y=pos.y+1, z=pos.z   })
-	pzm=0
+	local nzm = minetest.env:get_node({ x=pos.x  , y=pos.y  , z=pos.z-1 })
-	pzp=0
+	local nzp = minetest.env:get_node({ x=pos.x  , y=pos.y  , z=pos.z+1 })
 
-	nxm = minetest.env:get_node({ x=pos.x-1, y=pos.y  , z=pos.z   })
+	local nctr = minetest.env:get_node(pos)
-	nxp = minetest.env:get_node({ x=pos.x+1, y=pos.y  , z=pos.z   })
-	nym = minetest.env:get_node({ x=pos.x  , y=pos.y-1, z=pos.z   })
-	nyp = minetest.env:get_node({ x=pos.x  , y=pos.y+1, z=pos.z   })
-	nzm = minetest.env:get_node({ x=pos.x  , y=pos.y  , z=pos.z-1 })
-	nzp = minetest.env:get_node({ x=pos.x  , y=pos.y  , z=pos.z+1 })
 
-	if is_tube(nxm.name) 
+-- handle the tubes themselves
-		or minetest.get_item_group(nxm.name, "tubedevice") == 1 then pxm=1 end
+
-	if is_tube(nxp.name) 
+	if is_tube(nxm.name) then pxm=1 end
-		or minetest.get_item_group(nxp.name, "tubedevice") == 1 then pxp=1 end
+	if is_tube(nxp.name) then pxp=1 end
-	if is_tube(nym.name) 
+	if is_tube(nym.name) then pym=1 end
-		or minetest.get_item_group(nym.name, "tubedevice") == 1 then pym=1 end
+	if is_tube(nyp.name) then pyp=1 end
-	if is_tube(nyp.name) 
+	if is_tube(nzm.name) then pzm=1 end
-		or minetest.get_item_group(nyp.name, "tubedevice") == 1 then pyp=1 end
+	if is_tube(nzp.name) then pzp=1 end
-	if is_tube(nzm.name) 
+
-		or minetest.get_item_group(nzm.name, "tubedevice") == 1 then pzm=1 end
+-- handle regular filters
-	if is_tube(nzp.name) 
+
-		or minetest.get_item_group(nzp.name, "tubedevice") == 1 then pzp=1 end
+	if string.find(nxm.name, "pipeworks:filter") ~= nil
+	  and (nxm.param2 == 0 or nxm.param2 == 2) then
+		pxm=1 end
+	if string.find(nxp.name, "pipeworks:filter") ~= nil
+	  and (nxp.param2 == 0 or nxp.param2 == 2) then
+		pxp=1 end
+	if string.find(nzm.name, "pipeworks:filter") ~= nil
+	  and (nzm.param2 == 1 or nzm.param2 == 3) then
+		pzm=1 end
+	if string.find(nzp.name, "pipeworks:filter") ~= nil
+	  and (nzp.param2 == 1 or nzp.param2 == 3) then
+		pzp=1 end
+
+-- handle mese filters
+
+	if string.find(nxm.name, "pipeworks:mese_filter") ~= nil
+	  and (nxm.param2 == 0 or nxm.param2 == 2) then
+		pxm=1 end
+	if string.find(nxp.name, "pipeworks:mese_filter") ~= nil
+	  and (nxp.param2 == 0 or nxp.param2 == 2) then
+		pxp=1 end
+
+	if string.find(nzm.name, "pipeworks:mese_filter") ~= nil
+	  and (nzm.param2 == 1 or nzm.param2 == 3) then
+		pzm=1 end
+	if string.find(nzp.name, "pipeworks:mese_filter") ~= nil
+	  and (nzp.param2 == 1 or nzp.param2 == 3) then
+		pzp=1 end
+
+-- handle deployers
+
+	if string.find(nxm.name, "pipeworks:deployer_") ~= nil
+	  and nxm.param2 == 1 then
+		pxm=1 end
+	if string.find(nxp.name, "pipeworks:deployer_") ~= nil
+	  and nxp.param2 == 3 then
+		pxp=1 end
+	if string.find(nzm.name, "pipeworks:deployer_") ~= nil
+	  and nzm.param2 == 0 then
+		pzm=1 end
+	if string.find(nzp.name, "pipeworks:deployer_") ~= nil
+	  and nzp.param2 == 2 then
+		pzp=1 end
+
+--node breakers
+
+	if string.find(nxm.name, "pipeworks:nodebreaker_") ~= nil
+	  and nxm.param2 == 1 then
+		pxm=1 end
+	if string.find(nxp.name, "pipeworks:nodebreaker_") ~= nil
+	  and nxp.param2 == 3 then
+		pxp=1 end
+	if string.find(nzm.name, "pipeworks:nodebreaker_") ~= nil
+	  and nzm.param2 == 0 then
+		pzm=1 end
+	if string.find(nzp.name, "pipeworks:nodebreaker_") ~= nil
+	  and nzp.param2 == 2 then
+		pzp=1 end
+
+-- autocrafter
+
+	if string.find(nxm.name, "pipeworks:autocrafter") ~= nil then pxm = 1 end
+	if string.find(nxp.name, "pipeworks:autocrafter") ~= nil then pxp = 1 end
+	if string.find(nym.name, "pipeworks:autocrafter") ~= nil then pym = 1 end
+	if string.find(nyp.name, "pipeworks:autocrafter") ~= nil then pyp = 1 end
+	if string.find(nzm.name, "pipeworks:autocrafter") ~= nil then pzm = 1 end
+	if string.find(nzp.name, "pipeworks:autocrafter") ~= nil then pzp = 1 end
+
+--chests
+
+	-- check for left/right connects
+
+	if string.find(nxm.name, "default:chest") ~= nil
+	  and (nxm.param2 == 0 or nxm.param2 == 2) then
+		pxm=1 end
+	if string.find(nxp.name, "default:chest") ~= nil
+	  and (nxp.param2 == 0 or nxp.param2 == 2) then
+		pxp=1 end
+
+	if string.find(nzm.name, "default:chest") ~= nil
+	  and (nzm.param2 == 1 or nzm.param2 == 3) then
+		pzm=1 end
+	if string.find(nzp.name, "default:chest") ~= nil
+	  and (nzp.param2 == 1 or nzp.param2 == 3) then
+		pzp=1 end
+
+	-- check for backside connects
+
+	if string.find(nxm.name, "default:chest") ~= nil
+	  and nxm.param2 == 1 then
+		pxm = 1 end
+
+	if string.find(nxp.name, "default:chest") ~= nil
+	  and nxp.param2 == 3 then
+		pxp = 1 end
+
+	if string.find(nzm.name, "default:chest") ~= nil
+	  and nzm.param2 == 0 then
+		pzm = 1 end
+
+	if string.find(nzp.name, "default:chest") ~= nil
+	  and nzp.param2 == 2 then
+		pzp = 1 end
+
+	-- check for top/bottom connections
+
+	if string.find(nym.name, "default:chest") ~= nil then pym = 1 end
+	if string.find(nyp.name, "default:chest") ~= nil then pyp = 1 end
+
+	-- does not scan for the front side of the node.
+
+--chests
+
+	-- check for left/right connects
+
+	if string.find(nxm.name, "default:furnace") ~= nil
+	  and (nxm.param2 == 0 or nxm.param2 == 2) then
+		pxm=1 end
+	if string.find(nxp.name, "default:furnace") ~= nil
+	  and (nxp.param2 == 0 or nxp.param2 == 2) then
+		pxp=1 end
+
+	if string.find(nzm.name, "default:furnace") ~= nil
+	  and (nzm.param2 == 1 or nzm.param2 == 3) then
+		pzm=1 end
+	if string.find(nzp.name, "default:furnace") ~= nil
+	  and (nzp.param2 == 1 or nzp.param2 == 3) then
+		pzp=1 end
+
+	-- check for backside connects
+
+	if string.find(nxm.name, "default:furnace") ~= nil
+	  and nxm.param2 == 1 then
+		pxm = 1 end
+
+	if string.find(nxp.name, "default:furnace") ~= nil
+	  and nxp.param2 == 3 then
+		pxp = 1 end
+
+	if string.find(nzm.name, "default:furnace") ~= nil
+	  and nzm.param2 == 0 then
+		pzm = 1 end
+
+	if string.find(nzp.name, "default:furnace") ~= nil
+	  and nzp.param2 == 2 then
+		pzp = 1 end
+
+	-- check for bottom connection
+
+	if string.find(nyp.name, "default:furnace") ~= nil then pyp = 1 end
+
+	-- does not scan for the front or top side of the node.
+
+-- Apply the final routing decisions to the existing tube (if any)
 
 	nsurround = pxm..pxp..pym..pyp..pzm..pzp
 	if is_tube(nctr.name) then

compat.lua

@@ -39,8 +39,8 @@ furnace.after_place_node= function(pos)
 	furnace.after_dig_node = function(pos)
 		tube_scanforobjects(pos)
 	end
-minetest.register_node(":default:furnace",furnace)
 
+minetest.register_node(":default:furnace",furnace)
 
 furnace=clone_node("default:furnace_active")
 	furnace.groups.tubedevice=1
@@ -74,6 +74,7 @@ furnace.after_dig_node = function(pos)
 	end
 	minetest.register_node(":default:furnace_active",furnace)
 
+
 chest=clone_node("default:chest")
 	chest.groups.tubedevice=1
 	chest.groups.tubedevice_receiver=1
@@ -88,6 +89,11 @@ chest.tube={insert_object=function(pos,node,stack,direction)
 		return inv:room_for_item("main",stack)
 	end,
 	input_inventory="main"}
-chest.after_place_node = tube_scanforobjects(pos)
+	chest.after_place_node = function(pos)
-chest.after_dig_node = tube_scanforobjects
+		tube_scanforobjects(pos)
+	end
+	chest.after_dig_node = function(pos)
+		tube_scanforobjects(pos)
+	end
+
 minetest.register_node(":default:chest",chest)

item_transport.lua

@@ -33,6 +33,9 @@ minetest.register_node("pipeworks:filter", {
 	after_place_node = function(pos)
 		tube_scanforobjects(pos)
 	end,
+	after_dig_node = function(pos)
+		tube_scanforobjects(pos)
+	end,
 	mesecons={effector={action_on=function(pos,node)
 					minetest.registered_nodes[node.name].on_punch(pos,node,nil)
 				end}},
@@ -125,6 +128,12 @@ minetest.register_node("pipeworks:mese_filter", {
 		local inv = meta:get_inventory()
 		return inv:is_empty("main")
 	end,
+	after_place_node = function(pos)
+		tube_scanforobjects(pos)
+	end,
+	after_dig_node = function(pos)
+		tube_scanforobjects(pos)
+	end,
 	mesecons={effector={action_on=function(pos,node)
 					minetest.registered_nodes[node.name].on_punch(pos,node,nil)
 				end}},