Spot sp;

void setup() {
  size(500,500);
  smooth();
  noStroke();
  sp = new Spot(33, 50, 30, 1.5);
}

void draw() {
  fill(0,15);
  rect(0,0,width,height);
  fill(255);
if (mousePressed == true) {
  sp = new Spot(mouseX, mouseY, 30, mouseY%20);
}
  sp.move();
  sp.display();
}

class Spot {
  float x,y;
  float diameter;
  float speed;
  int direction = 1;

  Spot(float xpos, float ypos, float dia, float sp) {
    x = xpos;
    y = ypos;
    diameter = dia;
    speed = sp;
  }

  void move() {
    y += (speed * direction);

    if ((y > (height - diameter/2)) ||  (y < diameter/2)) {
      direction *= -1;
    }
  }

  void display () {
    ellipse(x, y, diameter, diameter);
  }
}