moving_object.js

(function(root) {
	var Asteroids = root.Asteroids = (root.Asteroids || {});

	var MovingObject = Asteroids.MovingObject = function(pos, vel, radius, color)  {
		this.pos = pos;
		this.vel = vel;
		this.radius = radius;
		this.color = color;
	};

	Function.prototype.inherits = function (superClass){
		function Surrogate(){};
		Surrogate.prototype = superClass.prototype;
		this.prototype = new Surrogate();
	};

	MovingObject.prototype.move = function () {
		this.pos = [this.pos[0] + this.vel[0], this.pos[1] + this.vel[1]];
	};

	MovingObject.prototype.draw = function (ctx) {
		ctx.fillStyle = this.color;
		ctx.beginPath();
		ctx.arc(
			this.pos[0],
			this.pos[1],
			this.radius,
			0,
			2 * Math.PI,
			false
		);
		ctx.fill();
	};

	MovingObject.prototype.isCollidedWith = function (otherObject) {
		var xdiff = this.pos[0] - otherObject.pos[0];
		var ydiff = this.pos[1] - otherObject.pos[1];
		var distance = Math.sqrt(xdiff * xdiff + ydiff * ydiff);
		return (this.radius + otherObject.radius > distance);
	};

	MovingObject.prototype.isOffEdge = function (game) {
	  return ((this.pos[0] + this.radius > game.DIM_X) ||
 			     (this.pos[0] + this.radius < 0)     ||
 				   ((this.pos[1] + this.radius) > game.DIM_Y) ||
			     (this.pos[1] + this.radius < 0))
	};

	MovingObject.prototype.wrapObject = function (game) {
		if (this.pos[0] - this.radius - 1 > game.DIM_X) {
			this.pos[0] = -this.radius;
		} else if (this.pos[0] - this.radius - 1 < 0) {
			this.pos[0] = game.DIM_X + this.radius;
		} else if (this.pos[1] - this.radius - 1 > game.DIM_Y) {
			this.pos[1] = -this.radius;
		} else if (this.pos[1] - this.radius - 1 < 0) {
			this.pos[1] = game.DIM_Y + this.radius;
		}
	};

})(this);