Spot[] sp = new Spot[300];
 
void setup() {
  size(600, 600);
  background(255);
  smooth();
  for (int i = 0; i < sp.length; i++) {
    sp[i] = new Spot(
     random(width/2-10, width/2+10),
      random(height/2-10, height/2+10 ) ,
      random(1, height/20),
      random(2.5, 5)
    );

  }
}
 
void draw() {
  for (int i = 0; i < sp.length; i++) {
    sp[i].moved();
    sp[i].display();
  }
}
 
 
class Spot {
  float x, y, diameter, speed;
  float h = random(256);
  float b_diameter;
   
  Spot(float _x, float _y, float _diameter, float _speed) {
    x = _x;
    y = _y;
    diameter = _diameter;
    speed = _speed;
    b_diameter = diameter;
  }
   
 void moved(){
    diameter = b_diameter*sin(frameCount*speed*PI/400);
  }
   
  void display() {
    colorMode(HSB);
    fill(h, 255, 255, 1);
    noStroke();
    if (mousePressed == true){ ellipse(mouseX, mouseY, diameter, diameter);
  }
  }
}