var LINES = 500;

function giveLine(x1,x2,mod){
  var line = { 
    X1:x1, 
    X2:x2, 
    Color:'#'+('00'+(Math.random()*0x4096<<0).toString(16)).substr(-3),
    Mod:mod
  };
  return line;
}

function draw(){
  var canvas = document.getElementById('canvas');
  if (canvas.getContext){
    var ctx = canvas.getContext('2d');

    var lines = Array();
    var modflip = 1;
    for (var i = 0 ; i < LINES; i++){
      lines[i] = giveLine(canvas.width/2, canvas.width/2, (Math.random()*10)*modflip);
      modflip = modflip*(-1);
    }

    ctx.globalAlpha = 1;
    ctx.lineWidth = 6;
    var animate = function (){
      ctx.clearRect(0,0,canvas.width,canvas.height);

      for (var i = 0; i < LINES; i++){
        line = lines[i];
        
        ctx.strokeStyle = line.Color;
        ctx.beginPath();
        ctx.moveTo(line.X1,0);
        ctx.lineTo(line.X2,canvas.height);
        ctx.stroke();

        line.X1 += line.Mod;
        line.X2 += line.Mod;
        if (line.X1 < 1 || line.X1 > canvas.width-1){
          line.Mod = line.Mod*(-1);
        }
      }
    };
    setInterval(animate,100);
  }
}

dojo.addOnLoad(draw);