Point p;
float lastX, lastY;
float x, y;
float speedX, speedY;
color c;

void setup() {
  size(600, 600);
  colorMode(HSB, 360, 100, 100, 100);
  smooth();
  x = random(width);
  y = random(height);
  p = new Point(1, 2);
  speedX = random(100);
  speedY = random(10);
  c = color(random(360), 30, 100);
  background(c);
}

void draw() {
  p = new Point(x, y);
  noStroke();
  fill(c);
     c = color(random(360), 30, 100);
  ellipse((float)p.x, (float)p.y, 100, 100);
  
  x += speedX;
  y += speedY;

  if (x > width)
    {
      x = width;
      speedX *= -1;
    }
    if (y > height)
    {
      y = height;
      speedY *= -1;
    }
    if (x < 0)
    {
      x = 0;
      speedX *= -1;
    }
    if (y < 0)
    {
      y = 0;
      speedY *= -1;
    }

}

public final class Point { 
    private final double x;    // x-coordinate
    private final double y;    // y-coordinate
   
    // random point
    public Point() {
        x = 0;
        y = 0;
    }

    // point initialized from parameters
    public Point(double x, double y) {
        this.x = x;
        this.y = y;
    }
    
    // accessor methods
    public double x() { return x; }
    public double y() { return y; }
    public double r() { return Math.sqrt(x*x + y*y); }
    public double theta() { return Math.atan2(y, x); }

    // Euclidean distance between this point and that point
    public double distanceTo(Point that) {
        double dx = this.x - that.x;
        double dy = this.y - that.y;
        return Math.sqrt(dx*dx + dy*dy);
    }

    // return a string representation of this point
    public String toString() {
        return "(" + x + ", " + y + ")";
    } 
}