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POcanvas.onmousedown function to add a shape won't work
 

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  1. POcanvas.onmousedown function to add a shape won't work
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    <p>I have some code, which can be seen below. At the bottom is a block of code to add a shape. For some reason it won't work unless the very first lines of code are different. Up until I added the 'addShape' code, it was all working fine, so I wandered if anyone on here could have a look and perhaps figure out a solution? </p> <p>Cheers</p> <p>Jon</p> <p><strong>EDIT</strong> Also available on jsFiddle <a href="http://jsfiddle.net/pukster/mfNq4/1/" rel="nofollow">http://jsfiddle.net/pukster/mfNq4/1/</a></p> <pre><code>$(document).ready(function() { var canvas = $('#myCanvas'); var ctx = canvas.get(0).getContext("2d"); var context = new webkitAudioContext(); var canvasWidth = canvas.width(); var canvasHeight = canvas.height(); $(window).resize(resizeCanvas); function resizeCanvas() { canvas.attr("width", $(window).get(0).innerWidth - 2); canvas.attr("height", $(window).get(0).innerHeight - 2); canvasWidth = canvas.width(); canvasHeight = canvas.height(); }; resizeCanvas(); ctx.strokeStyle = "rgb(255, 0, 0)"; ctx.lineWidth = 2; var playAnimation = true; var Ring = function(x, y, radius, vx, vy) { this.x = x; this.y = y; this.radius = radius; this.vx = vx; this.vy = vy; }; var rings = []; for (var i = 0; i &lt; 10; i++) { var x = Math.random()*ctx.canvas.width; var y = Math.random()*ctx.canvas.height; var vx = Math.random()*6-3; var vy = Math.random()*6-3; rings.push(new Ring(x, y, 40, vx, vy)); }; function animate() { var ringsLength = rings.length; ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); for (var i = 0; i &lt; ringsLength; i++) { var tmpRing = rings[i]; for (var j = i+1; j &lt; ringsLength; j++) { var tmpRingB = rings[j]; var dx = tmpRingB.x - tmpRing.x; var dy = tmpRingB.y - tmpRing.y; var dist = Math.sqrt((dx * dx) + (dy * dy)); if(dist &lt; tmpRing.radius + tmpRingB.radius) { var sinewave = new SineWave(context); var angle = Math.atan2(dy, dx); var sine = Math.sin(angle); var cosine = Math.cos(angle); var x = 0; var y = 0; var xb = dx * cosine + dy * sine; var yb = dy * cosine - dx * sine; var vx = tmpRing.vx * cosine + tmpRing.vy * sine; var vy = tmpRing.vy * cosine - tmpRing.vx * sine; var vxb = tmpRingB.vx * cosine + tmpRingB.vy * sine; var vyb = tmpRingB.vy * cosine - tmpRingB.vx * sine; vx *= -1; vxb *= -1; xb = x + (tmpRing.radius + tmpRingB.radius); tmpRing.x = tmpRing.x + (x * cosine - y * sine); tmpRing.y = tmpRing.y + (y * cosine + x * sine); tmpRingB.x = tmpRing.x + (xb * cosine - yb * sine); tmpRingB.y = tmpRing.y + (yb * cosine + xb * sine); tmpRing.vx = vx * cosine - vy * sine; tmpRing.vy = vy * cosine + vx * sine; tmpRingB.vx = vxb * cosine - vyb * sine; tmpRingB.vy = vyb * cosine + vxb * sine; tmpRing.loop = true; }; }; tmpRing.x += tmpRing.vx; tmpRing.y += tmpRing.vy; if (tmpRing.x - tmpRing.radius &lt; 0) { var sinwave = new SinWave(context); tmpRing.x = tmpRing.radius; tmpRing.vx *= -1; } else if (tmpRing.x + tmpRing.radius &gt; ctx.canvas.width) { var sinwave = new SinWave(context); tmpRing.x = ctx.canvas.width - tmpRing.radius; tmpRing.vx *= -1; }; if (tmpRing.y - tmpRing.radius &lt; 0) { var sinwave = new SinWave(context); tmpRing.y = tmpRing.radius; tmpRing.vy *= -1; } else if (tmpRing.y + tmpRing.radius &gt; ctx.canvas.height) { var sinwave = new SinWave(context); tmpRing.y = ctx.canvas.height - tmpRing.radius; tmpRing.vy *= -1; }; ctx.beginPath(); ctx.arc(tmpRing.x, tmpRing.y, 40, 0, Math.PI*2, false); ctx.closePath(); ctx.stroke(); //-------------------- The addRing Function Code --------------------// var mx, my; var offsetX, offsetY; //canvas.onmousedown = sglClick; function addRing(x, y, radius, vx, vy) { var x = mx-5; var y = my-5; var vx = Math.random()*6-3; var vy = Math.random()*6-3; rings.push(new Ring(x, y, 40, vx, vy)); } function sglClick(e) { getMouse(e); addRing(); } function getMouse(e) { var element = ctx, offsetX = 0, offsetY = 0; if (element.offsetParent !== undefined) { do { offsetX += element.offsetLeft; offsetY += element.offsetTop; } while ((element = element.offsetParent)); } mx = e.pageX - offsetX; my = e.pageY - offsetY; } }; if(playAnimation) { setTimeout(animate, 33); }; }; animate(); }); </code></pre>
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