Commands

In this small tutorial we show you how you can make your own console commands (server side in this case). The command we add here is a simple 'tp' command that allows the player to teleport to any dimension. We will use this command later to test our custom dimension.

So first lets make a TeleportCommand class which will implement the teleportation functionality. This is actually very simple. You just have to implement the methods from CommandBase:

public class TeleportCommand extends CommandBase {

    public TeleportCommand(){
        aliases = Lists.newArrayList(ModTut.MODID, "TP", "tp");
    }

    private final List<String> aliases;

    @Override
    @Nonnull
    public String getName() {
        return "tp";
    }

    @Override
    @Nonnull
    public String getUsage(@Nonnull ICommandSender sender) {
        return "tp <id>";
    }

    @Override
    @Nonnull
    public List<String> getAliases() {
        return aliases;
    }

    @Override
    public void execute(@Nonnull MinecraftServer server, @Nonnull ICommandSender sender, @Nonnull String[] args) throws CommandException {
        if (args.length < 1) {
            return;
        }
        String s = args[0];
        int dim;
        try {
            dim = Integer.parseInt(s);
        } catch (NumberFormatException e) {
            sender.sendMessage(new TextComponentString(TextFormatting.RED + "Error parsing dimension!"));
            return;
        }

        if (sender instanceof EntityPlayer) {
            CustomTeleporter.teleportToDimension((EntityPlayer) sender, dim, 0, 100, 0);
        }
    }

    @Override
    public boolean checkPermission(MinecraftServer server, ICommandSender sender) {
        return true;
    }

    @Override
    @Nonnull
    public List<String> getTabCompletions(MinecraftServer server, ICommandSender sender, String[] args, @Nullable BlockPos targetPos) {
        return Collections.emptyList();
    }
}

To do the actual teleportation we need a CustomTeleporter class which is implemented like this. This class extends Teleporter to make sure that teleporting doesn't create a nether portal. The default vanilla implementation of Teleporter does this and for our purposes we don't want that. In addition, we also add a 'teleportToDimension' convenience method that we will call from our command above:

public class CustomTeleporter extends Teleporter {

    public CustomTeleporter(WorldServer world, double x, double y, double z) {
        super(world);
        this.worldServer = world;
        this.x = x;
        this.y = y;
        this.z = z;
    }

    private final WorldServer worldServer;
    private double x;
    private double y;
    private double z;

    @Override
    public void placeInPortal(@Nonnull Entity entity, float rotationYaw) {
        // The main purpose of this function is to *not* create a nether portal
        this.worldServer.getBlockState(new BlockPos((int) this.x, (int) this.y, (int) this.z));

        entity.setPosition(this.x, this.y, this.z);
        entity.motionX = 0.0f;
        entity.motionY = 0.0f;
        entity.motionZ = 0.0f;
    }


    public static void teleportToDimension(EntityPlayer player, int dimension, double x, double y, double z) {
        int oldDimension = player.getEntityWorld().provider.getDimension();
        EntityPlayerMP entityPlayerMP = (EntityPlayerMP) player;
        MinecraftServer server = player.getEntityWorld().getMinecraftServer();
        WorldServer worldServer = server.getWorld(dimension);
        player.addExperienceLevel(0);

        if (worldServer == null || worldServer.getMinecraftServer() == null){ //Dimension doesn't exist
            throw new IllegalArgumentException("Dimension: "+dimension+" doesn't exist!");
        }

        worldServer.getMinecraftServer().getPlayerList().transferPlayerToDimension(entityPlayerMP, dimension, new CustomTeleporter(worldServer, x, y, z));
        player.setPositionAndUpdate(x, y, z);
        if (oldDimension == 1) {
            // For some reason teleporting out of the end does weird things. Compensate for that
            player.setPositionAndUpdate(x, y, z);
            worldServer.spawnEntity(player);
            worldServer.updateEntityWithOptionalForce(player, false);
        }
    }
}

To actually make this command work we need to register it in our main mod class:

public class ModTut {

    ...

    @Mod.EventHandler
    public void serverLoad(FMLServerStartingEvent event) {
        event.registerServerCommand(new TeleportCommand());
    }
}