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LunarGdx

Getting Started

How Lunar Works

Lunar works by keeping track of players in their own entity classes. Those players are apart of worlds which keeps track of all players. Each player is responsible for updating their own position. Each player also will handle other player information and pass it along to the world.

Here you can view a few pre-made examples.

Components

Entities

Creating your own Player entity

Lunar comes with a entity that is already defined for you LunarPlayer. But if you wish to have more advanced behaviour or customization you can do this by extending LunarEntityPlayer or LunarPlayer.

Each player entity should extend LunarPlayer or LunarEntityPlayer.

public class Player extends LunarPlayer {

    public Player() {
        super(scaling, width, height, rotation);
    }

}

From here there are a few options you could configure.

• player.setPositionSendRate(ms) defines how often to send position updates to the server.
• player.setVelocitySendRate(ms) defines how often to send velocity updates to the server. setMoveSpeed(f)` is actually that, set your move speed.

It's as simple as that.

Player movement

By default LunarPlayer provides a movement system using WASD. If you wish to not use this you MUST override the update() method.

Player movement is provided via the move(x, y, rotation) method or by setting the velocity yourself. Players use Box2d by default, meaning impulses, forces or velocity is used instead of directly setting the position.

    public void doSomething() {
        this.player.move(1.0f, 0.0f, Rotation.FACING_LEFT);
    }

The snippet above applies a X velocity of 1.0 and sets the players rotation to left. If using the provided snippet, to stop movement you would simply apply a velocity of 0.0. this.player.move(0.0, 0.0f, Rotation.FACING_LEFT);

Otherwise, you could poll for input every update() and apply velocity yourself.

        if (Gdx.input.isKeyPressed(Input.Keys.A)) {
            velocity.set(-moveSpeed, 0f);
            rotation = Rotation.FACING_LEFT;
        } else if (Gdx.input.isKeyPressed(Input.Keys.D)) {
            velocity.set(moveSpeed, 0f);
            rotation = Rotation.FACING_RIGHT;
        }

Player movement protocol

By default LunarPlayer will send position and velocity updates every X interval set by you (150 ms, 100 ms default). If you want to do this manually, you MUST override the update() method.

To send position and velocity updates simply:

// send my position
connection.send(new CPacketPosition(connection.alloc(), currentRotation.ordinal(), currentX, currentY));

// send my velocity
connection.send(new CPacketVelocity(connection.alloc(), velocity.x, velocity.y,  currentRotation.ordinal()));

Player rotation is sent over the network by using the ordinal index of the enum.

Player Collision

Lunar includes a basic collision handler for players. To disable or enable this state simply:

this.player.setIgnoreOtherPlayerCollision(boolean)

If true, you would want to add a collision handler to your Box2d world using PlayerCollisionListener.

// for example
final World world = new World(Vector2.Zero, true);
world.setContactListener(new PlayerCollisionListener());

Spawning entities in a world.

The LunarEntity class provides public abstract void spawnEntityInWorld(LunarWorld world, float x, float y); method for spawning the entity in a Box2d world.

Its up to the extending class to implement this. The LunarEntityPlayer provides a default implementation which:

• Sets the current, previous and interpolated position to the X, Y provided.
• Creates a dynamic body type with fixed rotation.
• Sets the shape of the entity as a Polygon box (width / 2f, height / 2f)
• Sets the density of the entity as 1.0f
• Sets user data as LunarEntityPlayer

You can change this behavior simply by overriding spawnEntityInWorld.

Lunar worlds have no concept of a local player, only networked players.

Player rendering

Player rendering works by using a TextureAtlas of animations and idle states. The default player rendering only supports movement animations and idle states and nothing else.

You can create your own renderer with all the special features you desire by extending LunarPlayerRenderer. Otherwise using the default renderer is simple.

You have 2 ways of defining the TextureAtlas for use in the renderer.

Walking animations can be defined as walking_up, walking_down, walking_left, walking right. They each must have an index of 1 and 2. (Indicating two separate animations for each player leg).

Idle animations can defined as the same except for adding "_idle" at the end. For example: walking_up_idle. These don't need an index.

With that, everything should work by default, simply plug it in:

final TextureAtlas atlas = new TexureAtlas(...)
player.initializePlayerRendererAndLoad(atlas, true);

Otherwise, if you wish to use other naming conventions or have different names you have an option. Start by defining a map of walking and idle animations.

final Map<Rotation, String> walkingAnimations = new HashMap<>();
final Map<Rotation, String> idleAnimations = new HashMap<>();

Next, plug in the names of each animation, for example:

walkingAnimations.put(Rotation.FACING_UP, "character_up");
walkingAnimations.put(Rotation.FACING_DOWN, "character_down");
walkingAnimations.put(Rotation.FACING_LEFT, "character_left");
walkingAnimations.put(Rotation.FACING_RIGHT, "character_right");

idleAnimations.put(Rotation.FACING_UP, "character_up_idle");
idleAnimations.put(Rotation.FACING_DOWN, "character_down_idle");
idleAnimations.put(Rotation.FACING_LEFT, "character_left_idle");
idleAnimations.put(Rotation.FACING_RIGHT, "character_right_idle");

With that you could create a new instance of DefaultPlayerRenderer (or your own implementation) and plug in the values.

        // Supply the atlas, default rotation, walking and idle art,
        // width and height of the player and if position should be offset
        // to fit inside box2d collision.
        return new DefaultPlayerRenderer(
                atlas,
                Rotation.FACING_UP,
                walkingAnimations,
                idleAnimations,
                width * scaling,
                height * scaling,
                true);

Finally, to provide this to the player you must load first and then call the method.

renderer.load();
player.initializePlayerRendererWith(renderer);

Worlds

Protocol and Networking

Creating a server