add callback function when new game frame updates?

[GxDT]

Hello people of this forum.

Here is what you normally do when you wish to add a callback function for a keyboard key:

aKey = game.input.keyboard.addKey(Phaser.KeyCode.A);
aKey.onDown.add(AKeyPressed, this);

In my case I wish to add same callback function when a new game frame is updated. (Yes, I know there is a reserved update function for this stuff, but this is not how I want to use it)

[drhayes]

Why don't you want to use the update function in your state? That's exactly what it's for. Alternatively, you could make a Phaser.Plugin, add it to the PluginManager, and use its update function if you can't use your state's update function for some reason.

[GxDT]

Using update function works perfectly too. I just was exploring the API and ways to work with it.

Guess I owe an explanation on what is going on.

Here I'm working on 2D platformer game  AI.

function CrabBehaviour(crabSprite) {

	this.status = {
		patrol: false,
		patrolLeft: false,
		patrolRight: false,

		attacking: false
	}

	this.leftRallyPoint = 0;
	this.rightRallyPoint = 0;

	this.patrol = function(leftPoint, rightPoint) {

		this.leftRallyPoint = leftPoint;
		this.rightRallyPoint = rightPoint;

		this.status.patrol = true;

		if (!this.status.patrolLeft && !this.status.patrolRight) {
			this.status.patrolLeft = true;
			this.patrolLeft();
		}

	}

	this.patrolRight = function () {
		this.status.patrolLeft = false;
		this.status.patrolRight = true;
		game.physics.arcade.moveToXY(evil_crab, evil_crab.body.position.x + 1, evil_crab.body.position.y, 40);
	}

	this.patrolLeft = function () {
		this.status.patrolLeft = true;
		this.status.patrolRight = false;
		game.physics.arcade.moveToXY(evil_crab, evil_crab.body.position.x - 1, evil_crab.body.position.y, 40);
	}

	this.frameEvent = function () 
	{
		if (this.status.patrol)
		{
			if (crabSprite.body.position.x <= this.leftRallyPoint  && this.status.patrolLeft) {
				this.patrolRight();
			}

			if (crabSprite.body.position.x >= this.rightRallyPoint  && this.status.patrolRight) {
				this.patrolLeft();
			}
		}
	}
}

The this.frameEvent function is responsible for tracking of what is going on 'live' so it should be called every time a new frame comes up. (In this case - change movement direction when left or right rally point is reached.

[drhayes]

Ah, okay, that makes sense. I do something like that in a game I'm working on, where the AI/behaviors for certain sprites come from a bunch of separate objects (StayOnPlatform, WatchesHealth, etc). They use a combination of every-frame stuff (by overriding update) and event-driven stuff (did I just get hit, did my animation complete).