Constructor, scene re-use and parallel instance

Phaser 3
1

Greetings!

New to Phaser here, porting my existing game from an ageing tech.

I’m getting trouble understanding the right “Phaser way” to declare a Scene’s instance members; Other discussion make it clear that the constructor only runs once (example).

My use case is the following:

  • I’m using Phaser 3.23 with Typescript (+ Ionic, Capacitor & NgRx so TS is mandatory).
  • a “control scene” is started whenever switching levels (even small rooms - so it happens quite often).
  • that “control scene” adds the “content scenes” it needs with every switch, like “platformer foreground”, “platformer parallax background”, “mini-map”, “in-game hud”, etc.

First red flag in my approach:

  • I have to register a “shutdown” event handler to reset variables like the mock “this.instanceVariable”.
  • This, otherwise the variable retains its value from the previous scene run (see init() method).

Hence the concern:

  • My platformer game allows to teleport back and forth from the foreground to the background layer.
  • The platformer logic is held in a PlatformerScene.
    - I must run multiple “instances” of that PlatformerScene in parallel and need them to have isolate runtime members.

So the question, how is this situation usually handled? I don’t imagine I’m doing rocket science, maybe just headed the wrong way :wink:

~

Thanks in advance for your time,

NB. The following bit of code shows the “control scene” I’m busy with.

export class ControlScene extends Phaser.Scene {
  private layers: Phaser.Scene[] = [];
  private mainLayer: Phaser.Scene;
  private bgParallaxLayer: Phaser.Scene;
  private hudLayer: Phaser.Scene;
  private instanceVariable = 0; // To illustrate the "red flag", see cleanup() below

  constructor() {
    super({ key: "controlScene" });
  }

  init(data) {
    this.events.on("shutdown", this.onShutdown, this);
    console.log("variable: " + this.instanceVariable++);

  }

  create(sceneData: any) {
    const { delegate } = this.plugins.get(DelegatePlugin.ID) as DelegatePlugin;
    /* ... implementation ... */
  }

  run(sceneData: SceneSetData) {
    this.scene.start("controlScene", sceneData);
  }

  /* ... class implementation ... */

  private cleanup() {
    this.layers.forEach((layer) => this.scene.remove(layer));
    this.layers.length = 0;
    this.instanceVariable = 0; // First red flag, this suggest "I'm not using Phaser the right way"
  }

  private onShutdown() {
    this.cleanup();
  }
}
2

Hi :wave:t2:
if you are trying to launch same scene each time without sharing its data, and if I understood well, you are looking for something similar to this?

for(let i = 0; i < 3; i++) {
    let key = 'Spawn' + i;
    let spawned = new Spawn(key);
    this.scene.add(key, spawned, true);
}

Look at it here:

3

Hi!
Thanks indeed it’s what I was looking for. I understand now that the key is used to tell the instance apart.
Cheers,