MoreMesecons/moremesecons_jammer/init.lua

local JAMMER_MAX_DISTANCE = 10

-- see wireless jammer
local get = vector.get_data_from_pos
local set = vector.set_data_to_pos
local remove = vector.remove_data_from_pos

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

local 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

minetest.after(0, function() -- After loading all mods, override some functions
	local jammed

	local actual_node_get = minetest.get_node_or_nil
	local function temp_node_get(pos, ...)
		local node = actual_node_get(pos, ...)
		if jammed == nil
		and node then
			jammed = is_jammed(pos)
		end
		return node
	end

	local actual_is_conductor_off = mesecon.is_conductor_off
	local function temp_is_conductor_off(...)
		if jammed then
			-- go to the next elseif, there's is_effector
			return
		end
		local v = actual_is_conductor_off(...)
		if v then
			-- it continues to the next frontier
			jammed = nil
		end
		return v
	end

	local actual_is_effector = mesecon.is_effector
	local function temp_is_effector(...)
		local abort_here = jammed
		-- the last elseif before continuing, jammed needs to be nil then
		jammed = nil
		if abort_here then
			return
		end
		return actual_is_effector(...)
	end

	local actual_turnon = mesecon.turnon
	function mesecon.turnon(...)
		--set those to the temporary functions
		minetest.get_node_or_nil = temp_node_get
		mesecon.is_conductor_off = temp_is_conductor_off
		mesecon.is_effector = temp_is_effector

		actual_turnon(...)

		minetest.get_node_or_nil = actual_node_get
		mesecon.is_conductor_off = actual_is_conductor_off
		mesecon.is_effector = actual_is_effector

		-- safety
		jammed = nil
	end
end)

mesecon.register_node("moremesecons_jammer:jammer", {
	description = "Mesecons 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_jammer: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_jammer:jammer_off"})
		end
	}},
	on_destruct = remove_jammer,
	on_construct = add_jammer,
})

minetest.register_craft({
	output = "moremesecons_jammer:jammer_off",
	recipe = {{"group:mesecon_conductor_craftable", "default:mese", "group:mesecon_conductor_craftable"},
		{"", "moremesecons_wireless:jammer_off", ""}}
})

minetest.register_lbm({
	name = "moremesecons_jammer:add_jammer",
	nodenames = {"moremesecons_jammer:jammer_on"},
	action = add_jammer
})