this.actions.die() kills multiple actors.

[nparoski]

I have player actor which spawns projectile actors which have range actors, when Projectile stops colliding with Range they both need to die. Problem I have is all of projectiles die.

Projectile 1. and Range1. (blue circle) need to die, but both do: image e.g

Simplified code example:
Note: must click outside circle

import { Color, Actor, Engine, vec, Vector } from 'excalibur';

const game = new Engine({
  width: 800,
  height: 600,
  backgroundColor: Color.Black,
});

class Player extends Actor {
  constructor() {
    super({
      width: 38,
      height: 64,
      color: Color.Cyan,
      pos: vec(125, 125),
    });
  }

  _initProjectile(_engine: Engine, moveTo: Vector) {
    const projectile = new Actor({
      width: 24,
      height: 24,
      color: Color.Red,
      pos: this.pos,
    });

    const range = new Actor({
      radius: 200,
      color: Color.fromRGB(25, 255, 25, 0.5),
      pos: this.pos,
      z: -1,
    });

    projectile.actions.moveTo(moveTo, 200);

    range.on('collisionend', () => {
      projectile.actions.clearActions();
      projectile.actions.die();
      range.actions.die();
    });

    _engine.add(projectile);
    _engine.add(range);
  }

  onInitialize(_engine: Engine): void {
    _engine.input.pointers.on('down', (evt) => {
      if (evt.button == 'Left') {
        this._initProjectile(_engine, evt.worldPos);
      }
    });
  }
}

game.add(new Player());

game.start();

[eonarheim]

Hi @nparoski, good question this is a tricky one!

I think the issue is that the range.on('collisionend', ...) will fire on any collision end event. So for example you have 2 projectiles, when the first triggers collisionend both handlers for each projectile will fire.

I think one way to work around this is to invert the logic and have projectile.on('collisionend', ...) that way the handler will fire per projectile.

Another way might be to check the evt arg to verify it's the projectile you want to kill

range.on('collisionend', (evt) => { 
  if (evt.other ===  projectile) {
    // kill
  }

})

[nparoski]

Makes sense, but I would expect this event to be fired when that specific actor collisionended rather than all actors on screen 🤔

[eonarheim]

Makes sense, but I would expect this event to be fired when that specific actor collisionended rather than all actors on screen 🤔

It's a little more subtle, since range is experiencing a collisionend event from some actor, without using evt.other the handler doesn't know which closed over projectile is the one that "ended" it's collision.

Another strategy you can use if your range is always circular you could add a projectile.onPostUpdate = () => {...} hook to check the distance between the player and the projectile.

projectile.onPostUpdate = () => {
   const distance = projectile.pos.distance(player.pos);
   if (distance > 200) {
      projectile.kill();
   }
}

[nparoski]

@eonarheim I'm actually trying to make projectile always collide with range.

When mouse is inside of circle projectile should go beyond and die when colliding with range.

Struggling with math little bit but I should be able to calculate it.