int frame=0;

void setup() {
  size(400,400);
  ellipseMode(CENTER_DIAMETER);  
}

void loop() {
  background(200,0,100);
  ellipse(150,150, 50,50);
  ellipse(random(width),random(height), 30,30);
  
  if(frame<20) saveFrame();
  frame++;
}