var old_x = size/2;

var old_y = size/2;

var angle = 0.0;

var offset = size/2;

var radius = 1;

var a_speed = 0.2;

var r_speed = 0.5;

​

function setup() { 

  createCanvas(600, 600);

  background(255);

} 

​

function draw() { 

  var x = offset + cos(angle) * radius;

  var y = offset + sin(angle) * radius;

  line(x, y, old_x, old_y);

  old_x = x;

  old_y = y;

  angle += a_speed; // TODO: fast at 1st, decreasing...

  radius += r_speed; // TODO: constant redraw...

}

​