重なる正方形

/**
* overlayed squares
*
* @author aa_debdeb
* @date 2016/09/15
*/

ArrayList<Square> squares;

void setup(){
  size(500, 500);
  strokeWeight(5);
  colorMode(HSB, 360, 100, 100);
  mousePressed();
}

void mousePressed(){
  squares = new ArrayList<Square>();
  for(int i = 0; i < 20; i++){
    squares.add(new Square());
  }
  background(0);
}

void draw(){
  rectMode(CORNER);
  fill(0, 100, 0, 10);
  noStroke();
  rect(0, 0, width, height);
  translate(width / 2, height / 2);
  for(Square s: squares){
    s.display();
    s.update();
  }
}

class Square{

  PVector loc;
  color c;
  
  Square(){
    float locAng = random(TWO_PI);
    loc = new PVector(500 * cos(locAng), 500 * sin(locAng));
    c = color(random(360), 100, 100, 40);
  }
  
  void display(){
    noFill();
    stroke(c);
    rectMode(CENTER);
    rect(loc.x, loc.y, 250, 250);
  }
  
  void update(){
    PVector vel = PVector.mult(loc, -1);
    vel.normalize();
    vel.limit(10);
    loc.add(vel);
  }
  
    
}