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CaioMGA

How to access parameters properly

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Hi!

I can access the x parameter on this.draw() function, why it doesn't work on this.updateRotation()??
After I create a Shooting Module on my game loop I can access the getX().
What I am missing?

function ShootingModule(_canvas){
	this.x = 200;
	this.y = 500;
	this.radius = 16;
	this.rotation = 0;
	this.canvas = _canvas;
	this.color = "blue";
	this.draw = function (context){
		context.beginPath();
		context.translate(this.x, this.y);
		context.rotate(this.rotation * Math.PI / 180);
		context.arc(0, 0, this.radius, 0, Math.PI * 2, true);
		context.fillStyle = this.color;
		context.fill();
		context.fillRect(-6, -this.radius -6, 12, 12);
		context.stroke();
		context.setTransform(1, 0, 0, 1, 0, 0);
	};
	this.updateRotation = function(e){
		console.log(this.x);
		this.rotation = Math.atan2(e.clientY - this.y, e.clientX - this.x);
	};
	this.update = function(){

	};

	this.getX = function(){
		return this.x;
	};
}

In my main loop script:

playerShootingModule = new ShootingModule(canvas);
canvas.addEventListener('mousemove', playerShootingModule.updateRotation, true);

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Care must be taken when referencing "this" in a callback function because the value of "this" will likely not be the object you actually want when the callback is invoked. You can ensure the callback references the desired "this" object by using bind:

canvas.addEventListener('mousemove', playerShootingModule.updateRotation.bind(playerShootingModule), true);

 

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6 hours ago, BobF said:

Care must be taken when referencing "this" in a callback function because the value of "this" will likely not be the object you actually want when the callback is invoked. You can ensure the callback references the desired "this" object by using bind:


canvas.addEventListener('mousemove', playerShootingModule.updateRotation.bind(playerShootingModule), true);

 

I see.
Thanks a lot.

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