Interactive Physics Animations Javascript Canvas 01

Adding a second circle, always at twice the x and y as the first. The first is still draggable. View the source: interactive physics animations via javascript & canvas | 01

[cc lang=”javascript”]
$(function () {
var canvas, context, width, height, x, y, radius = 25, clickX, clickY, drag = false;

canvas = $(“#canvas”)[0];
context = canvas.getContext(“2d”);
width = canvas.width;
height = canvas.height;
x = width / 2;
y = height / 2;
draw();

$(“#canvas”).mousedown(function (event) {
var dx, dy, dist;
dx = event.pageX – this.offsetLeft – x;
dy = event.pageY – this.offsetTop – y;
dist = Math.sqrt(dx * dx + dy * dy);
if(dist < radius) { drag = true; clickX = dx; clickY = dy; } else { drag = false; } }); $("#canvas").mouseup(function (event) { drag = false; }); $("#canvas").mousemove(function (event) { if(drag) { x = event.pageX - this.offsetLeft - clickX; y = event.pageY - this.offsetTop - clickY; draw(); } }); function draw() { context.clearRect(0, 0, width, height); context.beginPath(); context.arc(x, y, radius, 0, Math.PI * 2, false); context.arc(x*2, y*2, radius, 0, Math.PI * 2, false); context.fill(); } }); [/cc]