railcarts/launchers.lua

local dbg
if moddebug then dbg=moddebug.dbg("railcarts") else dbg={v1=function() end,v2=function() end,v3=function() end} end

minetest.register_craft({
    output = 'node "railcarts:launcher_off" 5',
    recipe = {
        {"default:cobble", "default:mese_crystal_fragment","default:cobble"},
        {"default:mese_crystal_fragment", "default:glass", "default:mese_crystal_fragment"},
        {"default:cobble", "default:mese_crystal_fragment","default:cobble"},
    }
})

minetest.register_craft({
    output = 'node "railcarts:cart_detector_off" 5',
    recipe = {
        {"default:cobble", "default:glass","default:cobble"},
        {"default:glass", "default:mese_crystal_fragment", "default:glass"},
        {"default:cobble", "default:glass","default:cobble"},
    }
})

minetest.register_craft({
    output = 'node "railcarts:autolauncher" 2',
    recipe = {
        {"default:cobble", "default:mese_crystal_fragment","default:cobble"},
        {"default:mese_crystal_fragment", "default:chest", "default:mese_crystal_fragment"},
        {"default:cobble", "default:mese_crystal_fragment","default:cobble"},
    }
})

minetest.register_craft({
    output = 'node "railcarts:launcher_off" 2',
    recipe = {
        {"default:cobble", "default:mese_crystal_fragment","default:cobble"},
        {"default:mese_crystal_fragment", "default:sand", "default:mese_crystal_fragment"},
        {"default:cobble", "default:mese_crystal_fragment","default:cobble"},
    }
})
minetest.register_node("railcarts:launcher_off", {
    description = "Cart Launcher",
    tiles ={"railcarts_launcher_off.png"},
    is_ground_content = true,
    groups = {cracky=3, mesecon=2},

    mesecons = { conductor = {
        state = "off",
        onstate = "railcarts:launcher_on",
    } }
})

minetest.register_node("railcarts:launcher_on", {
    description = "Cart Launcher",
    tiles ={"railcarts_launcher_on.png"},
    is_ground_content = true,
    groups = {cracky=3, mesecon=2},
    drop = 'railcarts:launcher_off 1',

    mesecons = { conductor = {
        state = "on",
        offstate = "railcarts:launcher_off",
    } }

})

minetest.register_node("railcarts:autolauncher", {
    description = "Cart Autolauncher",
    tiles ={"railcarts_autolauncher.png"},
    is_ground_content = true,
    groups = {cracky=3},
    drop = 'railcarts:autolauncher 1',
    on_construct = function(pos)
        local meta = minetest.get_meta(pos)
        meta:set_string("formspec",
        "size[8,8]"..
        "list[current_name;main;0,0;8,3;]"..
        "list[current_player;main;0,4;8,4;]")
        meta:set_string("infotext", "Autolauncher")
        local inv = meta:get_inventory()
        inv:set_size("main", 24)
    end,
    can_dig = function(pos,player)
        local meta = minetest.get_meta(pos);
        local inv = meta:get_inventory()
        return inv:is_empty("main")
    end,
})

minetest.register_abm({
    nodenames = {"railcarts:autolauncher"},
    neighbors = {},
    interval = 5.0,
    chance = 1,
    action =
        function(pos, node, active_object_count, active_object_count_wider)
            local meta = minetest.get_meta(pos)
            local inv = meta:get_inventory()

            tests = {{x=pos.x+1,y=pos.y,z=pos.z},
                     {x=pos.x-1,y=pos.y,z=pos.z},
                     {x=pos.x,y=pos.y,z=pos.z+1},
                     {x=pos.x,y=pos.y,z=pos.z-1},
                     {x=pos.x,y=pos.y-1,z=pos.z}}

            for _, testpos in ipairs(tests) do
               
                if is_rail(minetest.get_node(testpos)) then

                    -- Check there's not a cart (or anything else, like a mob) in the way
                    -- TODO: I think the block can be loaded, but the objects not active,
                    -- in which case this will drop another cart on top of an existing
                    -- one ad infinitum - needs fixing!
                    already = minetest.get_objects_inside_radius(testpos, 1)
                    if table.maxn(already) == 0 then

                        -- Get a cart from the autolauncher's inventory
                        local stack = inv:remove_item("main", ItemStack("railcarts:cart"))
                        local placecart = "railcarts:cart_ent"
                        if stack:is_empty() then
                            stack = inv:remove_item("main", ItemStack("railcarts:cargo_cart"))
                            if stack:is_empty() then
                                stack = inv:remove_item("main", ItemStack("railcarts:boring_cart"))
                                if stack:is_empty() then
                                    dbg.v1("Autolauncher at "..postostr(pos).." is empty")
                                    return
                                end
                                placecart = "railcarts:boring_cart_ent"
                            else
                                placecart = "railcarts:cargo_cart_ent"
                            end
                        end

                        dbg.v1("Autolauncher placing "..placecart.." at"..postostr(testpos))

                        local object = minetest.add_entity(testpos, placecart)
                        if object then
                            local ent = object:get_luaentity()
                            local newdir = xz_to_direction({x=testpos.x-pos.x, z=testpos.z-pos.z})
                            current_state = {direction=newdir}
                            cartbase.setdirection(ent, current_state, newdir)
                            ent.direction = newdir
                        end
                    end
                end
            end

        end,
})