var canvas = document.getElementById("concentric_circles");
var ctx = canvas.getContext("2d");
var canvasWidth = canvas.width;
var canvasHeight = canvas.height;
var circles = new Array();
function Circle(angle, radius, rRadius, iX, iY) {
Circle.prototype.add = function () {
this.cX = this.iX + this.rRadius * Math.cos(this.angle);
this.cY = this.iY + this.rRadius * Math.sin(this.angle);
if (this.angle >= (Math.PI * 2)) {
this.inc = .01 + Math.random() * .1;
var rColor = 'rgba(' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ', .3)';
ctx.arc(this.cX, this.cY, this.radius, 0, Math.PI * 2);
ctx.strokeStyle = rColor;
for (var i = 0; i < 30 ; i++) {