spacecannon/cannon.lua

local register_spacecannon = function(def)

	local entity_texture = "energycube_" .. def.color .. ".png"

	minetest.register_entity("spacecannon:energycube_" .. def.color, {
		initial_properties = {
			visual = "cube",
			visual_size = {x=0.25, y=0.25},
			textures = {entity_texture,entity_texture,entity_texture,entity_texture,entity_texture,entity_texture},
			collisionbox = {-0.25,-0.25,-0.25, 0.25,0.25,0.25},
			physical = false
		},
		timer = 0,
		static_save = false,

		on_step = function(self, dtime)
			self.timer = self.timer + dtime
			local pos = self.object:getpos()

			if self.timer > 0.5 then
				-- add sparks along the way
				minetest.add_particlespawner({
						amount = 5,
						time = 0.5,
						minpos = pos,
						maxpos = pos,
						minvel = {x = -2, y = -2, z = -2},
						maxvel = {x = 2, y = 2, z = 2},
						minacc = {x = -3, y = -3, z = -3},
						maxacc = {x = 3, y = 3, z = 3},
						minexptime = 1,
						maxexptime = 2.5,
						minsize = 0.5,
						maxsize = 0.75,
						texture = "spacecannon_spark.png",
						glow = 5
				})
				self.timer = 0
			end

			local node = minetest.get_node(pos)

			if node.name == "air" or node.name == "vacuum:vacuum" then
				local objs = minetest.get_objects_inside_radius({x=pos.x,y=pos.y,z=pos.z}, 3)
				local collided = false
				for k, obj in pairs(objs) do
					if obj:get_luaentity() ~= nil and obj:get_luaentity().name ~= self.name then
						collided = true
						obj:punch(self.object, 1.0, {
								full_punch_interval=1.0,
								damage_groups={fleshy=def.range*2},
							}, nil)
					end
				end

				if collided then
					spacecannon.destroy(pos, def.range)
					self.object:remove()
				end

			elseif node.name ~= "air" and node.name ~= "vacuum:vacuum" then
				-- collision
				spacecannon.destroy(pos, def.range)
				self.object:remove()

			end
		end,

		on_activate = function(self, staticdata)
				minetest.after(def.timeout, 
					function(self) 
						self.object:remove()
					end,
					self)
		end

	})



	minetest.register_node("spacecannon:cannon_" .. def.color, {
		description = "Spacecannon (" .. def.desc .. ")",
		-- top, bottom
		tiles = {
			"cannon_blank.png",
			"cannon_front_" .. def.color .. ".png",
			"cannon_blank.png",
			"cannon_blank.png",
			"cannon_blank.png",
			"cannon_blank.png"
		},

		groups = {cracky=3,oddly_breakable_by_hand=3,technic_machine = 1, technic_hv = 1},
		drop = "spacecannon:cannon_" .. def.color,
		sounds = default.node_sound_glass_defaults(),
		paramtype2 = "facedir",
		legacy_facedir_simple = true,

		mesecons = {effector = {
			action_on = function (pos, node)
				spacecannon.fire(pos, def.color, def.speed, def.range)
			end
		}},

		connects_to = {"group:technic_hv_cable"},
		connect_sides = {"bottom", "top", "left", "right", "front", "back"},

		after_place_node = function(pos, placer)
			local meta = minetest.get_meta(pos)
			meta:set_string("owner", placer:get_player_name() or "")
		end,

		on_construct = function(pos)
			local meta = minetest.get_meta(pos)
			meta:set_int("powerstorage", 0)

			meta:set_int("HV_EU_input", 0)
			meta:set_int("HV_EU_demand", 0)

			spacecannon.update_formspec(meta)
		end,

		technic_run = function(pos, node)
			local meta = minetest.get_meta(pos)
			local eu_input = meta:get_int("HV_EU_input")
			local demand = meta:get_int("HV_EU_demand")
			local store = meta:get_int("powerstorage")

			meta:set_string("infotext", "Power: " .. eu_input .. "/" .. demand .. " Store: " .. store)

			if store < spacecannon.config.powerstorage * def.range then
				-- charge
				meta:set_int("HV_EU_demand", spacecannon.config.powerrequirement)
				store = store + eu_input
				meta:set_int("powerstorage", store)
			else
				-- charged
				meta:set_int("HV_EU_demand", 0)
			end
		end,

		on_receive_fields = function(pos, formname, fields, sender)
			local meta = minetest.get_meta(pos);

			if fields.fire then
				spacecannon.fire(pos, def.color, def.speed, def.range)
			end
		end

	})

	technic.register_machine("HV", "spacecannon:cannon_" .. def.color, technic.receiver)

	minetest.register_craft({
		output = 'spacecannon:cannon_' .. def.color,
		recipe = {
			{'', 'default:steelblock', ''},
			{ def.ingredient, def.ingredient, def.ingredient},
			{'', 'default:steelblock', ''}
		}
	})



end

register_spacecannon({
	color = "green",
	range = 1,
	timeout = 8,
	speed = 10,
	desc = "fast,low damage",
	ingredient = "default:mese_block"
})

register_spacecannon({
	color = "yellow",
	range = 3,
	timeout = 8,
	speed = 5,
	desc = "medium speed, medium damage",
	ingredient = "spacecannon:cannon_green"
})

register_spacecannon({
	color = "red",
	range = 5,
	timeout = 15,
	speed = 3,
	desc = "slow, heavy damage",
	ingredient = "spacecannon:cannon_yellow"
})