float x,y,radius;

void setup() {
  size(300,300);
  ellipseMode(CENTER_DIAMETER);
  rectMode(CENTER_DIAMETER);
  x=0;
  y=random(height);
  radius=random(10, 30);
  
  framerate(20);
}

void loop() {
  background(200);
  ellipse(width/2,height/2, 40,40);
  ellipse(mouseX,mouseY, 10,10);
  
  x=x+5;  
  if(x>width) {
    x=0;
    y=random(height);
    radius=random(10, 30);
  }
  
  rect(x,y, radius,radius);

}