Pretty thing in Javascript

// Try it, run in about:blank and paste in the console

document.body.appendChild(c=document.createElement("canvas"));
c.width = 800;
c.height = 800;

var ctx = c.getContext("2d");
ctx.fillRect(0,0,800,800)

var ctr = 0;

function deg2rad(a) {
  return (((a%360)+360)%360) / (180/Math.PI);
}

var ps = [];
var I = 0;
function p(x,y,a) {
  if ((I=(I+1)%3)==0)ps.push([x,y,a]);
  for (var i = 0; i < ps.length; i++) {
    var x = ps[i][0],
        y = ps[i][1],
        a = ps[i][2];
    ctx.strokeStyle="hsl("+a+",50%,70%)";
    ctx.beginPath();
    ctx.moveTo(x,y);
    x += Math.sin(deg2rad(a)) * 1.2;
    y += Math.cos(deg2rad(a)) * 1.2;
    ctx.lineTo(x,y);
    ctx.stroke();
    ps[i] = [x,y,a];
  }
  ps = ps.filter(function (p) {
    return!(p[0] < -5 || p[0] > 805 || p[1] < -5 || p[1] > 805);
  })
}

ctx.lineWidth = 4;
ctx.fillStyle = "#000";
ctx.lineCap = "round";

function draw() {
  ctr = (ctr + 4.4) % 360;
  ctx.globalAlpha = 0.04;
  ctx.fillRect(0,0,800,800);
  ctx.globalAlpha = 1;
  p(400,400,ctr);
};

function frame() {
  requestAnimationFrame(frame);
  draw();
}
frame();