Collision callback firing multiple times

Phaser 3
1

I’m creating an rpg/jrpg using Phaser 3. When the hero collides with a monster, from a group, I’m switching/starting a battle scene for turn based combat:

this.physics.add.collider(this.player, this.spawns, this.onMeetEnemy, false, this);

onMeetEnemy(player, monster) {        
    this.cameras.main.shake(300);   this.cameras.main.on('camerashakecomplete', () => {
      this.scene.start('Battle', {player: this.player, monster: monster});
    });
  }

The collisions happen and the battle scene is started. But, the battle scene is created multiple times, like 8-9 times. I understand why, because they are still colliding. So how do I get the collision callback function to fire only once and commence battle? My best guess is set a variable that says we’re fighting, don’t execute onMeetEnemy anymore until further notice. Also should I be starting or switching to Battle?

Hope I was clear enough and thank you for the help.

EDIT: I have changed meetEnemy() to:

onMeetEnemy(player, monster) {        
    this.cameras.main.shake(300);
    this.cameras.main.on('camerashakecomplete', () => {
      if(!this.isFighting){
        this.isFighting = true;
        // start battle
        //this.scene.switch('Battle', {player: this.player, monster: monster});
        this.scene.start('Battle', {player: this.player, monster: monster});
      }
    });
  }

Seems to work, but is this the best/ most common way to do this?

2

This way is fine - I do similar things.
You could also disable the body, or (I’m a bit less sure as I don’t know which physics you’re working with) remove the listener (so something like this.physics.remove.collider…)

The only thing you’d need to be careful of is if you return to the scene - just making sure you’ve reset everything. With the way you’re doing it, it’s really easy to reset this.isFighting.

1 Like
3

I will check into disabling the body and removing the listener. I am using arcade physics right now. I did read some stuff about removing the listener, but if the hero flees, I may still need it, but I suppose I could recreate it as needed. Thank you for pointing me in the right direction.

4

Looks like processCallback in the collide function may be the way to do it the phaser way.

5

processCallback, the fourth parameter of the collider function, is the correct answer, I believe. Thanks to charlie_says’ answer I went in search of and found: how-to-disable-collision-for-body. And here is my final collider that fires once until the variable inBattleScene is reset.

in Game scene create method:

this.inBattleScene = false;

this.physics.add.collider(
  this.player, 
  this.spawns, 
  this.onMeetEnemy, // collision stuff, launch battle scene
  this.enterBattleScene // should this collider fire? must return true or false
);

then create functions outside create:

enterBattleScene(){
  if (!this.inBattleScene) {
    this.inBattleScene = true;
    return true;  
  }  
  return false;
}

onMeetEnemy(player, monster) {        
  this.cameras.main.shake(300);
  this.cameras.main.on('camerashakecomplete', () => {
    this.scene.start('Battle', {player: this.player, monster: monster});
  });
}