int num = 20;
color bg = #ffffff;
color s = #000000;
Circle circles[] = new Circle[num];

void setup() {
  size(500, 500);
  background(bg);
  stroke(s,150);
  fill(s,50);
  float maxw = 0;
  float theta = 0;

  for (int i=0; i<num; i++) {
    maxw += 20;

    circles[i] = new Circle(maxw, theta);
    theta += TAU/num;
  }
}

void draw() {
  background(bg);
  for (int i=0; i<circles.length; i++) {
    circles[i].run();
  }
  
  //if (frameCount % 4 == 0 && frameCount < 121) saveFrame("image-####.gif");
  
  
}
class Circle {
  float w, maxw, h, theta, str;

  Circle(float _maxw, float _theta) {
    maxw = _maxw;
    theta = _theta;
  }

  void run() {
    move();
    display();
  }

  void move() {
    w = map(sin(theta), -1, 1, -maxw, maxw);
    h = map(cos(theta), -1, 1, maxw/3, maxw);
    theta += 0.0523;
  }

  void display() {
    ellipse(width/2, height/2, w, h);
  }
}