Scene Lifecycle

Scene provides complete lifecycle management for proper resource initialization and cleanup.

Lifecycle Methods

class ExampleScene extends Scene {
  protected initialize(): void {
    // 1. Scene initialization: setup systems and initial entities
    console.log("Scene initializing");
  }

  public onStart(): void {
    // 2. Scene starts running: game logic begins execution
    console.log("Scene starting");
  }

  public update(deltaTime: number): void {
    // 3. Per-frame update (called by scene manager)
  }

  public unload(): void {
    // 4. Scene unloading: cleanup resources
    console.log("Scene unloading");
  }
}

Execution Order

Phase	Method	Description
Initialize	initialize()	Setup systems and initial entities
Start	begin() / onStart()	Scene starts running
Update	update()	Per-frame update (auto-called)
End	end() / unload()	Cleanup resources

Lifecycle Example

class GameScene extends Scene {
  private resourcesLoaded = false;

  protected initialize(): void {
    this.name = "GameScene";

    // 1. Add systems (by dependency order)
    this.addSystem(new InputSystem());
    this.addSystem(new MovementSystem());
    this.addSystem(new RenderSystem());

    // 2. Create initial entities
    this.createPlayer();
    this.createEnemies();

    // 3. Setup event listeners
    this.setupEvents();
  }

  public onStart(): void {
    this.resourcesLoaded = true;
    console.log("Scene resources loaded, game starting");
  }

  public unload(): void {
    // Cleanup event listeners
    this.eventSystem.clear();

    // Cleanup other resources
    this.resourcesLoaded = false;
    console.log("Scene resources cleaned up");
  }

  private createPlayer(): void {
    const player = this.createEntity("Player");
    player.addComponent(new Position(400, 300));
  }

  private createEnemies(): void {
    for (let i = 0; i < 5; i++) {
      const enemy = this.createEntity(`Enemy_${i}`);
      enemy.addComponent(new Position(Math.random() * 800, Math.random() * 600));
    }
  }

  private setupEvents(): void {
    this.eventSystem.on('player_died', () => {
      console.log('Player died');
    });
  }
}

Notes

1. initialize() called once - For initial state setup
2. onStart() on scene activation - May be called multiple times
3. unload() must cleanup resources - Avoid memory leaks
4. update() managed by framework - No manual calls needed