int howmany = 50;
Circle[] Cir = new Circle[howmany]; 

void setup () {
  size(400,500);
  framerate(30);

  init_Circles();
}

void init_Circles() {
  for (int i=0;i<Cir.length;i++) {
    Cir[i] = new Circle(
    int(random(width)),
    int(random(height)),
    int(random(-10,10)),
    int(random(-10,10)),
    color(random(255),random(255),random(250))
      );
  }
}

void draw () {
  background(255);
  for (int i=0; i<Cir.length;i++) {
    Cir[i].draw_Circle();  
    Cir[i].move_Circle(); 

  }
}




class Circle {
  int xpos; 
  int ypos; 
  int xspeed;
  int yspeed; 
  color circle_color; 
  int circle_width = 10; 
  int circle_height = 10;
  int x_bnd, y_bnd;


  Circle(int xp, int yp, int xs, int ys, color cc) {
    xpos = xp; 
    ypos = yp; 
    
    xspeed = xs; 
    if (xspeed == 0) xspeed = 5;
    
    yspeed = ys; 
    if (yspeed == 0) yspeed = 7;
      
    circle_color = cc;
    
    x_bnd =(100+circle_width/2); 
    y_bnd = (50+circle_height/2); 

   
  }
  
  

  void draw_Circle () {
    stroke(0);
   noFill ();
 rect (100, 50, 200, 300);
 
 noStroke();
 smooth();
    fill(circle_color); 
    ellipse(xpos,ypos,circle_width,circle_height); 
  }

  void move_Circle() {
    xmove(); 
    ymove(); 
  }

  void xmove() {
    xpos += xspeed;
    if (xpos+x_bnd >= 400) {
      xpos = 400-x_bnd;
      xspeed *= -1;
    }
    else if (xpos-x_bnd <= 0) {
      xpos = x_bnd;
      xspeed *= -1;
    }
  }

  void ymove() {
    ypos += yspeed;
    if (ypos+y_bnd >= 400) {
      ypos = 400 - y_bnd;
      yspeed *= -1;
    }
    else if (ypos-y_bnd <= 0) {
      ypos = y_bnd;
      yspeed *= -1;
    }
  }


}