Fix mesecon control of forcefield

The code formerly attempted to make the forcefield emitter controlled
both manually and by (inverted) mesecon signal, but the two interfered
with each other.  In particular, a newly-placed emitted would be
informed that it was getting no mesecon signal, and would therefore
enable itself.  Fix this by adding explicit modes for how the emitter
will respond to mesecon signals: ignore them, obey them positively,
or obey them negatively.

The manual control could have been incorporated into this mode setting
by having two "ignore mesecon" modes: always-enabled and always-disabled.
But it seems more useful to have a separate manual master switch, so that
the emitter can be manually disabled without losing the mesecon mode.
So it is now implemented that way.

technic/locale/template.txt

@@ -55,6 +55,9 @@ Slot %d =
 Mode: %s =
 single items =
 whole stacks =
+Ignoring Mesecon Signal =
+Controlled by Positive Mesecon Signal =
+Controlled by Inverted Mesecon Signal =
 
 ## Machine names
 # $1: Tier

technic/machines/HV/forcefield.lua

@@ -63,12 +63,19 @@ local function update_forcefield(pos, range, active)
 end
 
 local function set_forcefield_formspec(meta)
-	local formspec = "size[5,1.5]"..
+	local formspec = "size[5.5,2.25]"..
-		"field[2,0.5;2,1;range;"..S("Range")..";"..meta:get_int("range").."]"
+		"field[2.25,0.5;2,1;range;"..S("Range")..";"..meta:get_int("range").."]"
-	if meta:get_int("enabled") == 0 then
+	if meta:get_int("mesecon_mode") == 0 then
-		formspec = formspec.."button[0,1;5,1;enable;"..S("%s Disabled"):format(S("%s Forcefield Emitter"):format("HV")).."]"
+		formspec = formspec.."button[0,1;5.5,1;mesecon_mode_1;"..S("Ignoring Mesecon Signal").."]"
+	elseif meta:get_int("mesecon_mode") == 1 then
+		formspec = formspec.."button[0,1;5.5,1;mesecon_mode_2;"..S("Controlled by Positive Mesecon Signal").."]"
 	else
-		formspec = formspec.."button[0,1;5,1;disable;"..S("%s Enabled"):format(S("%s Forcefield Emitter"):format("HV")).."]"
+		formspec = formspec.."button[0,1;5.5,1;mesecon_mode_0;"..S("Controlled by Inverted Mesecon Signal").."]"
+	end
+	if meta:get_int("enabled") == 0 then
+		formspec = formspec.."button[0.25,1.75;5,1;enable;"..S("%s Disabled"):format(S("%s Forcefield Emitter"):format("HV")).."]"
+	else
+		formspec = formspec.."button[0.25,1.75;5,1;disable;"..S("%s Enabled"):format(S("%s Forcefield Emitter"):format("HV")).."]"
 	end
 	meta:set_string("formspec", formspec)
 end
@@ -89,16 +96,19 @@ local forcefield_receive_fields = function(pos, formname, fields, sender)
 	end
 	if fields.enable then meta:set_int("enabled", 1) end
 	if fields.disable then meta:set_int("enabled", 0) end
+	if fields.mesecon_mode_0 then meta:set_int("mesecon_mode", 0) end
+	if fields.mesecon_mode_1 then meta:set_int("mesecon_mode", 1) end
+	if fields.mesecon_mode_2 then meta:set_int("mesecon_mode", 2) end
 	set_forcefield_formspec(meta)
 end
 
 local mesecons = {
 	effector = {
 		action_on = function(pos, node)
-			minetest.get_meta(pos):set_int("enabled", 0)
+			minetest.get_meta(pos):set_int("mesecon_effect", 1)
 		end,
 		action_off = function(pos, node)
-			minetest.get_meta(pos):set_int("enabled", 1)
+			minetest.get_meta(pos):set_int("mesecon_effect", 0)
 		end
 	}
 }
@@ -107,14 +117,14 @@ local run = function(pos, node, active_object_count, active_object_count_wider)
 	local meta = minetest.get_meta(pos)
 	local eu_input   = meta:get_int("HV_EU_input")
 	local eu_demand  = meta:get_int("HV_EU_demand")
-	local enabled    = meta:get_int("enabled")
+	local enabled = meta:get_int("enabled") ~= 0 and (meta:get_int("mesecon_mode") == 0 or (meta:get_int("mesecon_mode") == 1 and meta:get_int("mesecon_effect") ~= 0) or (meta:get_int("mesecon_mode") == 2 and meta:get_int("mesecon_effect") == 0))
 	local machine_name = S("%s Forcefield Emitter"):format("HV")
 
 	local power_requirement = math.floor(
 			4 * math.pi * math.pow(meta:get_int("range"), 2)
 		) * forcefield_power_drain
 
-	if meta:get_int("enabled") == 0 then
+	if not enabled then
 		if node.name == "technic:forcefield_emitter_on" then
 			meta:set_int("HV_EU_demand", 0)
 			update_forcefield(pos, meta:get_int("range"), false)
@@ -149,6 +159,8 @@ minetest.register_node("technic:forcefield_emitter_off", {
 		meta:set_int("HV_EU_demand", 0)
 		meta:set_int("range", 10)
 		meta:set_int("enabled", 0)
+		meta:set_int("mesecon_mode", 0)
+		meta:set_int("mesecon_effect", 0)
 		meta:set_string("infotext", S("%s Forcefield Emitter"):format("HV"))
 		set_forcefield_formspec(meta)
 	end,
@@ -162,11 +174,6 @@ minetest.register_node("technic:forcefield_emitter_on", {
 	groups = {cracky = 1, technic_machine = 1, not_in_creative_inventory=1},
 	drop = "technic:forcefield_emitter_off",
 	on_receive_fields = forcefield_receive_fields,
-	on_construct = function(pos) 
-		local meta = minetest.get_meta(pos)
-		local range = meta:get_int("range")
-		meta:set_string("formspec", get_forcefield_formspec(range))
-	end,
 	on_destruct = function(pos)
 		local meta = minetest.get_meta(pos)
 		update_forcefield(pos, meta:get_int("range"), false)