createCanvas(600, 600);

  smooth();

  background(255);

  ellipseMode(CENTER);

}

​

function draw() {

  stroke(0,20);

  noFill();

  push();

    translate(width/2,height/2);

    rotate(map(cos(0.1*frameCount), 0, 0.5, 0, TWO_PI));

    arc(0,0, 520, randomGaussian(20, 200), 0, random(PI+QUARTER_PI), OPEN);

  pop();

}