PALS3004: Web Programming Demo 9-4

<html>
<head>
<title>PALS3004: Web Programming Demo 9-4</title>
<script>
// plot the graph
function drawgraph() {
  // get canvas element and graph context
  var cnv=document.getElementById("canvas1");
  var ctx=cnv.getContext("2d");
  // clear background to blue
  ctx.fillStyle="SkyBlue";
  ctx.fillRect(0,0,cnv.width,cnv.height);
  // choose a couple of yellowish colours
  ctx.fillStyle="#f2f40f";
  ctx.strokeStyle="#d2d40f";
  // plot 1000 'seeds'
  for (var i=1;i<1000;i++) {
    var r=7*Math.sqrt(i);
    var theta=137.507*Math.PI*i/180;
    var x=r*Math.cos(theta);
    var y=r*Math.sin(theta);
    ctx.beginPath();
    ctx.arc(cnv.width/2+x,cnv.height/2+y,6,0,2*Math.PI);
    ctx.fill();
    ctx.stroke();
  }
}
</script>
</head>
<body onload="drawgraph()">

  <h2>Demo 9-4: Demonstrate Canvas Graphics</h2>

  <p><canvas id="canvas1" width="500" height="500" ></div>

  </body>
</html>

Demo 9-4: Demonstrate Canvas Graphics

A. Mathai, and T. Davis, Constructing the sunflower head, Mathematical Biosciences, 20 (1974) 117-133.