//
//	CannonBall class
//	Described in Chapter 6 of
//	Understanding Object-Oriented Programming with Java
//	by Timothy A Budd
//	Published by Addison-Wesley
//
//	see ftp://ftp.cs.orst.edu/pub/budd/java/ReadMe.html
//	for further information
//

/**
 * class CannonBall refines class Ball for gravity
 * 
 * @version 1.0
 * @author Timothy Budd
 *
 */

public class CannonBall extends Ball {

  /**
   *  Constructor to init both position, size, and motion
   *
   *  @param sx the initial x coordinate of the center 
   *  @param sy the initial y coordinate of the center 
   *  @param r the radius of the cannonball
   *  @param dx the initial delta along the x axis
   *  @param dy the initial delta along the y axis
   */
    public CannonBall (int sx, int sy, int r, double dx, double dy)
    {
	super(sx, sy, r);
	setMotion (dx, dy);
    }

  /** 
   * refine move for gravity effects
   * 
   */

    public void move ()
    {
	dy = dy + 0.3; // effect of gravity
	super.move();	// update the ball position
    }
}