//Motion.java

import java.awt.*;
import javax.swing.*;

public class Motion extends JApplet {     

    int moves, movesize, size, killtime;
    
    public void init() {
	String input;
	
	input = JOptionPane.showInputDialog( "Enter number of moves" );
	moves = Integer.parseInt( input );

	input = JOptionPane.showInputDialog( "Enter size of circle" );
	size = Integer.parseInt( input );

	input = JOptionPane.showInputDialog( "Enter distance of random move" );
	movesize = Integer.parseInt( input );
	
	input = JOptionPane.showInputDialog( "Enter count of time-killing loop" );
	killtime = Integer.parseInt( input );
    }
    
    
    public void paint (Graphics g) {
	
	int x=getWidth()/2;		//start in center of applet
	int y=getHeight()/2;
	int xd, yd;
	
	for (int i=1; i<=moves; i++) {
	    //"erase" current circle
	    g.setColor(Color.WHITE);
	    g.fillOval(x,y,size,size);
	    
	    //randomly: -1, 0, or 1
	    xd = (int)(Math.random()*3) - 1;
	    yd = (int)(Math.random()*3) - 1;
	    
	    //add -movesize, 0, or +movesize to coordinates
	    x = x + xd*movesize;
	    y = y + yd*movesize;
	    
	    //draw circle at new position
	    g.setColor(Color.RED);
	    g.fillOval(x,y,size,size);
	    
	    //slow it down...
	    for (int j=1; j<killtime; j++)
	    	Math.sqrt(Math.PI);
	}
    }
}