/* JavaBallsBall.java
 * Copyright 1997 Joel Peterson.
 * All rights reserved.
 *
 * Permission to use and distribute unmodified copies of this file is freely
 * granted, provided that this notice is included and credit is given.
 *
 * The following HTML source is an example of acceptable credit.  It should
 * be included on your web page in close proximity to your use of this code:
 *
 * (APPLICATION NAME) makes use of Java classes provided by
 * <A HREF="http://www.geocities.com/SiliconValley/Peaks/3639/javastuff.html">
 * Joel Peterson</A>.
 *
 * Permission to modify, use and distribute copies of this file is granted
 * provided that the above terms are followed and a disclaimer of the changes
 * made is included.
 *
 * Because the program is licensed free of charge, there is no warranty
 * for the program, to the extent permitted by applicable law.  Except when
 * otherwise stated in writing the I provide the program "as is" without
 * warranty of any kind, either expressed or implied, including, but not
 * limited to, the implied warranties of merchantability and fitness for
 * a particular purpose.  The entire risk as to the quality and performance
 * of the program is with you.  Should the program prove defective, you
 * assume the cost of all necessary servicing, repair or correction.
 *
 * In no event unless required by applicable law or agreed to in writing will
 * I be liable to you for damages, including any general, special, incidental
 * or consequential damages arising out of the use or inability to use the
 * program (including but not limited to loss of data or data being rendered
 * inaccurate or losses sustained by you or third parties or a failure of the
 * program to operate with any other programs), even if such holder or other
 * party has been advised of the possibility of such damages.
 */

import java.awt.*;
import java.util.*;

public class JavaBallsBall {
    private static Random r=new Random();
    private JavaBallsBall next;
    private double x,y,radius;
    private double dx,dy;
    private double accel;
    private static double prob;
    private boolean collided;

    JavaBallsBall(JavaBallsBall Next,Dimension Size) {
	radius=2.0+12.0*r.nextDouble();
	next=Next;
	x=(double)Size.width/2.0;
	y=(double)Size.height/2.0;
	if (r.nextDouble()<0.5) dx=-radius*r.nextDouble()-.00001;
	else dx=radius*r.nextDouble()+.00001;
	if (r.nextDouble()<0.5) dy=-radius*r.nextDouble()-.00001;
	else dy=radius*r.nextDouble()+.00001;
	accel=1.0;
	collided=false;
    }

    public static final void setProb(double Prob) {
	prob=Prob;
    }

    private void collide() {
	JavaBallsBall check;
	double dist,circledist;
	for (check=next;check!=null;check=check.next) {
	    dist=(x-check.x)*(x-check.x)+(y-check.y)*(y-check.y);
	    circledist=radius+check.radius;
	    if (dist<circledist*circledist) {
		check.collided=true;
		collided=true;
	    }
	}
    }

    public void update(JavaBallsBall prev,Dimension Size) {
	if (x+radius>(double)Size.width) {
	    // choose new dx;
	    dx=-radius*r.nextDouble()-.00001;
	    // choose a new accel
	    //accel=Math.sqrt(Math.abs(r.nextGaussian())+1.0);
	    x=Size.width-radius;
	}
	else if (x<radius) {
	    dx=radius*r.nextDouble()+.00001;
	    //accel=Math.sqrt(Math.abs(r.nextGaussian())+1.0);
	    x=radius;
	}
	else x=x+dx;
	if (y+radius>(double)Size.height) {
	    dy=-radius*r.nextDouble()-.00001;
	    //accel=Math.sqrt(Math.abs(r.nextGaussian())+1.0);
	    y=Size.height-radius;
	}
	else if (y<radius) {
	    dy=radius*r.nextDouble()+.00001;
	    //accel=Math.sqrt(Math.abs(r.nextGaussian())+1.0);
	    y=radius;
	}
	else y=y+dy;
	// collision check
	collide();
	if (next!=null) next.update(this,Size);
    }

    public final void paint(Graphics g,JavaBallsBall prev,
			    JavaBallsAnimation parent) {
	if (collided) {
	    if (r.nextDouble()>prob) {
		double xr,yr;
		g.setColor(Color.yellow);
		if (r.nextDouble()>0.5) {
		    xr=2*radius;
		    yr=radius;
		}
		else {
		    xr=radius;
		    yr=2*radius;
		}
		g.fillOval((int)(x-xr),(int)(y-yr),
			   2*(int)xr,2*(int)yr);
		next=new JavaBallsBall(next,parent.size());
		next.x=x+next.radius;
		next.y=y+next.radius;
		x=x-radius;
		y=y-radius;
		next.paint(g,this,parent);
	    }
	    else {
		g.setColor(Color.red);
		g.drawLine((int)(x-radius),(int)y,(int)(x+radius),(int)y);
		g.drawLine((int)x,(int)(y-radius),(int)x,(int)(y+radius));
		if (prev!=null) prev.next=next;
		else parent.setBalls(next);
		if (next!=null) next.paint(g,prev,parent);
	    }
	}
	else {
	    g.setColor(Color.blue);
	    g.fillOval((int)(x-radius),(int)(y-radius),
		       2*(int)radius,2*(int)radius);
	    if (next!=null) next.paint(g,this,parent);
	}
    }
}