Hi

I'm making a field of asteroids and try to change colors in two ways. Btw I'm a beginner with this.

First is to have all the androids colored randomly and second is two have them colored in lets say 3 different predefined colors.

Thanks guys...

Code:
$(document).ready(function() {
	var canvas = $("#myCanvas");
	var context = canvas.get(0).getContext("2d");
	var canvasWidth = canvas.width();
	var canvasHeight = canvas.height();
	$(window).resize(resizeCanvas);

	function resizeCanvas() {
		canvas.attr("width", $(window).get(0).innerWidth);
		canvas.attr("height", $(window).get(0).innerHeight);
		canvasWidth = canvas.width();
		canvasHeight = canvas.height();
	};
	
	resizeCanvas();
	
	var playAnimation = true;
	var startButton = $("#startAnimation");
	var stopButton = $("#stopAnimation");
	startButton.hide();
	startButton.click(function() {
		$(this).hide();
		stopButton.show();
		playAnimation = true;
		animate();
	});

	stopButton.click(function() {
		$(this).hide();
		startButton.show();
		playAnimation = false;
	});
	
	var Asteroid = function(x, y, radius, color) {
		this.x = x;
		this.y = y;
		this.radius = radius;
		this.color = color;
		this.vX = vX;
		this.vY = vY;
	};

	var asteroids = new Array();
	for (var i = 0; i < 1000; i++) {
		var x = 20+(Math.random()*(canvasWidth-40));
		var y = 20+(Math.random()*(canvasHeight-40));
		var radius = 2+Math.random()*30; 
		var vX = Math.random()*4-2;
		var vY = Math.random()*4-2;
		var color = 'rgb(' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ')';
		asteroids.push(new Asteroid(x, y, radius, vX, vY, color));
		};

	function animate() {
		context.clearRect(0, 0, canvasWidth, canvasHeight);	
		//context.fillStyle = "rgb(255, 255, 255)";
				var asteroidsLength = asteroids.length;
		for (var i = 0; i < asteroidsLength; i++) {
			var tmpAsteroid = asteroids[i];
			tmpAsteroid.x += tmpAsteroid.vX;
			tmpAsteroid.y += tmpAsteroid.vY;
			
			if (tmpAsteroid.x-tmpAsteroid.radius < 0) {
				tmpAsteroid.x = tmpAsteroid.radius;
				tmpAsteroid.vX *= -1;
			} else if (tmpAsteroid.x+tmpAsteroid.radius > canvasWidth) {
				tmpAsteroid.x = canvasWidth-tmpAsteroid.radius;
				tmpAsteroid.vX *= -1;
			};
			if (tmpAsteroid.y-tmpAsteroid.radius < 0) {
				tmpAsteroid.y = tmpAsteroid.radius;
				tmpAsteroid.vY *= -1;
			} else if (tmpAsteroid.y+tmpAsteroid.radius > canvasHeight) {
				tmpAsteroid.y = canvasHeight-tmpAsteroid.radius;
				tmpAsteroid.vY *= -1;
			};
			
			
			context.beginPath();
			context.arc(tmpAsteroid.x, tmpAsteroid.y, tmpAsteroid.radius, 0, Math.PI*2, false);
			context.closePath();
			context.fill();
		};
		if (playAnimation) {
			setTimeout(animate, 33);
		};
	};
	
	animate();
});