import java.awt.*;
import java.applet.*;

import java.util.*;

public class Structure extends Applet implements Runnable
{
    final static int NUM_POINTS = 128;
    final static int SCALE = 4;
    final static int NUM_STEPS = 64;

    final static int SIZE = 256;
    final static int HALFSIZE = 128;
	boolean threadSuspended = false; //added by C.Y.
	Graphics gOff;
	Image im;


    Point dots[] = null;
    double where[] = null;
    double phase[] = null;
    double extent[] = null;
    Color color[]  = null;

    Thread kicker = null;

    public Structure()
    {
        dots = new Point[NUM_POINTS];
        phase = new double[NUM_POINTS];
        extent = new double[NUM_POINTS];
        where = new double[NUM_POINTS];
        color = new Color[NUM_STEPS*2];

        int i;
        for(i = 0; i < NUM_STEPS/2; i++)
        {
            color[i] = new Color(i * 4 + 128,    // red
                                 0,
                                 64 - i*2);
            color[NUM_STEPS - i -1] = new Color(color[i].getRGB());
        }

        for(i = 0; i < NUM_STEPS/2; i++)
        {
            color[NUM_STEPS+i] = new Color(128 - i*4,
                                           0,
                                           64 + i*6); //255 - i  * 12);
            color[NUM_STEPS*2 - i -1] = new Color(color[NUM_STEPS+i].getRGB());
        }
    }

    public void init()
    {
        resize(SIZE+6,SIZE+6);

        int i;
            Random r = new Random();


        for(i =0; i < NUM_POINTS; i++)
        {

            extent[i] = Math.sqrt(Math.sin(i*Math.PI/NUM_POINTS));
            dots[i] = new Point(0,0);
            dots[i].y = i * SIZE / NUM_POINTS;
            phase[i] = r.nextFloat() * Math.PI * 2;

        }

		im = createImage(size().width,size().height);
		gOff = im.getGraphics();


        repaint();
    }

    public void start()
    {
        if (kicker == null)
        {
            kicker = new Thread(this);
            kicker.start();
        }
    }

    public void stop()
    {
        if (kicker != null)
        {
            kicker.stop();
            kicker = null;
        }
    }

    public void run()
    {
            while(kicker != null)
            {
                try
                {
                    tick();
                    repaint();
                    kicker.sleep(200);
                }
                catch (InterruptedException e){}; // fixed by C.Y.
            }

    }
	// ** Added by C.Y.
	public boolean mouseDown(java.awt.Event evt, int x, int y) {
        if (threadSuspended) {
            kicker.resume();
        }
        else {
            kicker.suspend();
        }
        threadSuspended = !threadSuspended;
    return true;
    }
	// **

public void tick()
{
        double step = Math.PI/NUM_STEPS;
        double angle = 0;
        double twopi = 2*Math.PI;

        int i;
        for(i = 1; i < NUM_POINTS; i++)
        {
            where[i] = Math.cos( phase[i]);
             dots[i].x =(int) (HALFSIZE *( 1.0+ ( ( where[i]) * extent[i])));
            phase[i]+= step;
          if(phase[i] > twopi)
              phase[i] -= twopi;
    }

}

    public void update(Graphics g)
    {
        gOff.setColor(Color.black);
		gOff.fillRect(0,0,size().width,size().height);

        paint(gOff);

			g.drawImage(im,0,0,this);


    }

    public void paint(Graphics g)
    {
        int i;

        Dimension d = size();
        g.setColor(Color.red);
        g.drawRect(0,0,d.width-1,d.height-2);
        g.drawRect(1,1,d.width-2,d.height-3);
        g.drawRect(2,2,d.width-3,d.height-4);


        //for(i = 1; i< NUM_POINTS; i++)
	for(i = NUM_POINTS-1; i > 0; i--)
        {

            int c = (int)((where[i]+1.0)*32);

		
            int size = 6;	// modified by C.Y. in this part
int newsize= size+ (int) ( extent[i] * 4.0 + (Math.sin(where[i]+(Math.PI/2.0)) )*6.0);
            if(phase[i] > Math.PI)
            {
                c+= NUM_STEPS;
                size-=2;
		    newsize= size + (int) ( extent[i] * 4.0 );	// modified by C.Y.

            }

            g.setColor(color[c]);
            g.fillOval(dots[i].x,dots[i].y,newsize,newsize); // modified by C.Y.


        }
    }
}