basic_machines/ball.lua

-- BALL: energy ball that flies around, can bounce and activate stuff
-- rnd 2016:

--local obj = minetest.add_entity(pos, "basic_machines:ball")

minetest.register_entity("basic_machines:ball",{
	timer = 0, 
	lifetime = 20, -- how long it exists before disappearing
	owner = "",
	origin = {x=0,y=0,z=0},
	hp_max = 1,
	visual="sprite",
	visual_size={x=.50,y=.50},
	collisionbox = {0,0,0,0,0,0},
	physical=false,
	--textures={"basic_machines_ball"},
		on_punch=function(self, puncher, time_from_last_punch, tool_capabilities, dir) -- ball is punched
			
		end,
	on_activate = function(self, staticdata)
		self.object:set_properties({textures={"basic_machines_ball.png"}})
		self.object:setvelocity({x=0,y=0,z=0})
		self.timer = 0;self.owner = "";
		self.origin = self.object:getpos();
	end,
	
	on_step = function(self, dtime)
		self.timer=self.timer+dtime
		if self.timer>self.lifetime then 
			self.object:remove() 
			return 
		end
		
		local pos=self.object:getpos()
		
		local origin = self.origin;
		local r = 20;
		if math.abs(pos.x-origin.x)>r or math.abs(pos.y-origin.y)>r or math.abs(pos.z-origin.z)>r then -- remove if it goes too far
			self.object:remove() 
			return 
		end
		
		local nodename = minetest.get_node(pos).name;
		local walkable = false;
		if nodename ~= "air" then 
			walkable = minetest.registered_nodes[nodename].walkable;
		end

		if walkable then -- we hit a node
			--minetest.chat_send_all(" hit node at " .. minetest.pos_to_string(pos))
			self.object:remove() 
			
			local node = minetest.get_node(pos);
			local table = minetest.registered_nodes[node.name];
			if not table then return end -- error
			if not table.mesecons then return end 
			if not table.mesecons.effector then return end
			local effector=table.mesecons.effector;	if not effector.action_on then return end
			effector.action_on(pos,node,16); 
			
			--self.object:setvelocity({x=0, y=0, z=0})
			--self.object:setacceleration({x=0, y=0, z=0})
			return
			--return self
		end
		
		--self.object:setacceleration({x=0, y=0, z=0}) -- no gravity!
		
	end,
})


minetest.register_node("basic_machines:ball_spawner", {
	description = "Spawns energy ball one block above",
	tiles = {"basic_machines_ball.png"},
	groups = {oddly_breakable_by_hand=2,mesecon_effector_on = 1},
	drawtype = "liquid",
	walkable = false,
	alpha = 150,
	sounds = default.node_sound_wood_defaults(),
	after_place_node = function(pos, placer)
		local meta = minetest.env:get_meta(pos)
		meta:set_string("owner", placer:get_player_name()); 
	end,

	mesecons = {effector = {
		action_on = function (pos, node,ttl) 
			if ttl<0 then return end
			minetest.add_entity({x=pos.x,y=pos.y,z=pos.z}, "basic_machines:ball")
		end
		}
	},
})


minetest.register_craft({
	output = "basic_machines:ball_spawner",
	recipe = {
		{"basic_machines:power_cell"},
		{"basic_machines:keypad"}
	}
})