class Ball {
  int w;
  int h;
  float x;
  float y;
  float spdX;
  float spdY;
  float gravity = .03;

  // Constructor
  Ball() {
    w = h = 20;
    x = random(0, width/2);
    y = random(10, 20);
    spdX = random(0.5, 1.3);
    spdY = 0;
  }

  void update() {
    x += spdX; 
    spdY += gravity; 
    y += spdY;

    // reaching right or left edge, reverse x
    if (x + w/2 > width || x - w/2 < 0) {
      spdX = -spdX;
    }

    // reaching bottom or top edge, reverse y and apply damping
    if ( y + h/2 > height || y - h/2 < 0) {
      spdY = -spdY;
    }
  }

  void display() {
    ellipse(x, y, w, h);
  }
}