MoreMesecons/moremesecons_wireless/init.lua

local JAMMER_MAX_DISTANCE = 15

local wireless = {}
local wireless_rids = {}

-- localize these functions with small names because they work fairly fast
local get = vector.get_data_from_pos
local set = vector.set_data_to_pos
local remove = vector.remove_data_from_pos

-- if the wireless at pos isn't stored yet, put it into the tables
local function register_RID(pos)
	if get(wireless_rids, pos.z,pos.y,pos.x) then
		return
	end
	local RID = #wireless+1
	wireless[RID] = pos
	set(wireless_rids, pos.z,pos.y,pos.x, RID)
end

local is_jammed
local function wireless_activate(pos)
	if is_jammed(pos) then
		-- jamming doesn't disallow receiving signals, only sending them
		return
	end
	local channel_first_wireless = minetest.get_meta(pos):get_string("channel")
	for i = 1, #wireless do
		if not vector.equals(wireless[i], pos)
		and minetest.get_meta(wireless[i]):get_string("channel") == channel_first_wireless then
			mesecon.receptor_on(wireless[i])
		end
	end
end

local function wireless_deactivate(pos)
	if is_jammed(pos) then
		return
	end
	local channel_first_wireless = minetest.get_meta(pos):get_string("channel")
	for i = 1, #wireless do
		if not vector.equals(wireless[i], pos)
		and minetest.get_meta(wireless[i]):get_string("channel") == channel_first_wireless then
			mesecon.receptor_off(wireless[i])
		end
	end
end

minetest.register_node("moremesecons_wireless:wireless", {
	tiles = {"moremesecons_wireless.png"},
	paramtype = "light",
	paramtype2 = "facedir",
	description = "Wireless",
	walkable = true,
	groups = {cracky=3},
	mesecons = {effector = {
		action_on = wireless_activate,
		action_off = wireless_deactivate
	}},
	sounds = default.node_sound_stone_defaults(),
	on_construct = function(pos)
		local meta = minetest.get_meta(pos)
   		meta:set_string("formspec", "field[channel;channel;${channel}]")
   		register_RID(pos)
	end,
	on_destruct = function(pos)
		local RID = get(wireless_rids, pos.z,pos.y,pos.x)
		if RID then
			table.remove(wireless, RID)
			vector.remove_data_from_pos(wireless_rids, pos.z,pos.y,pos.x)
		end
	end,
	on_receive_fields = function(pos, formname, fields, sender)
		local meta = minetest.get_meta(pos)
		meta:set_string("channel", fields.channel)
	end,
})

local jammers = {}
local function add_jammer(pos)
	if get(jammers, pos.z,pos.y,pos.x) then
		return
	end
	set(jammers, pos.z,pos.y,pos.x, true)
end

local function remove_jammer(pos)
	remove(jammers, pos.z,pos.y,pos.x)
end

-- looks big, but should work fast
function is_jammed(pos)
	local pz,py,px = vector.unpack(pos)
	for z,yxs in pairs(jammers) do
		if math.abs(pz-z) <= JAMMER_MAX_DISTANCE then
			for y,xs in pairs(yxs) do
				if math.abs(py-y) <= JAMMER_MAX_DISTANCE then
					for x in pairs(xs) do
						if math.abs(px-x) <= JAMMER_MAX_DISTANCE
						and (px-x)^2+(py-y)^2+(pz-z)^2 <= JAMMER_MAX_DISTANCE^2 then
							return true
						end
					end
				end
			end
		end
	end
	return false
end

mesecon.register_node("moremesecons_wireless:jammer", {
	description="Wireless Jammer",
	paramtype = "light",
},{
	tiles = {"moremesecons_jammer_off.png"},
	groups = {dig_immediate=2},
	mesecons = {effector = {
		action_on = function(pos)
			add_jammer(pos)
			minetest.swap_node(pos, {name="moremesecons_wireless:jammer_on"})
		end
	}}
},{
	tiles = {"moremesecons_jammer_on.png"},
	groups = {dig_immediate=2, not_in_creative_inventory=1},
	mesecons = {effector = {
		action_off = function(pos)
			remove_jammer(pos)
			minetest.swap_node(pos, {name="moremesecons_wireless:jammer_off"})
		end
	}},
	on_destruct = remove_jammer,
	on_construct = add_jammer,
})

minetest.register_craft({
	output = "moremesecons_wireless:jammer_off",
	recipe = {
		{"moremesecons_wireless:wireless", "mesecons_torch:mesecon_torch_on", "moremesecons_wireless:wireless"}
	}
})

minetest.register_craft({
	output = "moremesecons_wireless:wireless 2",
	recipe = {
		{"group:mesecon_conductor_craftable", "", "group:mesecon_conductor_craftable"},
		{"", "mesecons_torch:mesecon_torch_on", ""},
		{"group:mesecon_conductor_craftable", "", "group:mesecon_conductor_craftable"},
	}
})

minetest.register_abm({
	nodenames = {"moremesecons_wireless:jammer_on"},
	interval = 5,
	chance = 1,
	action = add_jammer
})

minetest.register_abm({
	nodenames = {"moremesecons_wireless:wireless"},
	interval = 5,
	chance = 1,
	action = register_RID
})