Entity Controllers

Entity Controllers are the primary mechanism for defining how entities behave in LITIENGINE. Each controller manages a specific aspect of an entity’s functionality, such as animation, movement, or AI behavior.

Controller Architecture

Controllers implement the IEntityController interface and are attached to entities. The engine provides several built-in controller types:

AnimationController – Manages spritesheet animations
MovementController – Handles entity movement
BehaviorController – Controls AI and state machines

Adding Controllers to Entities

public class Player extends Creature {

  public Player() {
    super("player");

    // Add custom controller
    this.addController(new MyCustomController(this));
  }

  @Override
  protected IMovementController createMovementController() {
    return new KeyboardEntityController<>(this);
  }
}

The Controller Lifecycle

Controllers are automatically attached to the game loop when added to an entity:

public interface IEntityController extends IUpdateable {
  void attach();
  void detach();
  IEntity getEntity();
}

Built-in Controller Types

AnimationController

Controls which spritesheet animation is displayed for an entity. See Animation Controller for details.

MovementController

Handles entity movement, including velocity, direction, and collision response. See Movement Controller for details.

BehaviorController / StateController

Manages AI behavior and state machines. See Behavior Controller for details.

Creating Custom Controllers

Extend EntityController for custom behavior:

public class MyCustomController extends EntityController<MyEntity> {

  public MyCustomController(MyEntity entity) {
    super(entity);
  }

  @Override
  public void update() {
    // Called every tick while attached
    MyEntity entity = getEntity();

    // Custom logic here
    if (entity.isAlive()) {
      performCustomBehavior();
    }
  }

  private void performCustomBehavior() {
    // Custom behavior implementation
  }
}

Overriding Default Controllers

Entities can override which controllers are created:

@EntityInfo(width = 32, height = 32)
public class FlyingEnemy extends Creature {

  public FlyingEnemy() {
    super("flying-enemy");
  }

  @Override
  protected IMovementController createMovementController() {
    // Use custom flying movement instead of default
    return new FlyingMovementController<>(this);
  }

  @Override
  protected IEntityAnimationController<?> createAnimationController() {
    // Custom animation controller
    return new FlyingEnemyAnimationController(this);
  }
}

Accessing Controllers

// Get specific controller type
MovementController movement = entity.getController(MovementController.class);

// Get animation controller
IEntityAnimationController<?> anim = entity.getAnimationController();

// Get all controllers
List<IEntityController> controllers = entity.getControllers();

Controller Events

Controllers can define and fire custom events:

public class CombatController extends EntityController<Creature> {

  public void attack() {
    // Perform attack
    fireAttackEvent();
  }

  private void fireAttackEvent() {
    // Notify listeners
    getEntity().getListeners().forEach(l -> l.onAttack());
  }
}