/* Ikeda.java
* 
*	Provides a Java-based animation of an Ikeda Attractor.
*	Based on an algorithm from Clifford A. Pickover
*
*	@author L. Gladney
*	@version 0.0 December 13, 1999
*/

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import java.net.*;

public class Ikeda extends Applet implements Runnable, MouseListener, MouseMotionListener {
    Thread kicker=null;						//name of animation thread
    int delay=10;						// default sleep time for animation thread
    int strtx=5, strty=10;					// initial starting point for waves (in x,y)
    int npts=3000;						// default number of pts. to generate
    int r,gr,b;							// define color indices
    int wavefrontlength=140, wavefrontwidth=5;			// wavefront width, length (in pixels)
    int ptsrcwidth=5, ptsrcspacing=20;				// diameter, spacing of point sources
    int ptsrcdist=50;						// travel distance between source creations
    int stepdown=10;						// sets speed of response of animation to time
    int maxwidth=400;						// default dimensions for applet window
    int maxheight=400;
    double c1=0.0;
    double c1addto = 0.01;					// bump values for c1 parameter
    boolean runit=true;						// set flag to run as default
    boolean animgo=true;					// set animation flag off - let user start it
    int xbmp = strtx;						// keeps track of animation position x, y
    int ybmp = strty;
    int xlag, ylag, xset;					// x,y on surface, 1st intersection
    int xret, yret;						// retarded x,y positions for wavefront
    int initcnt = 0;						// keep track of initial calls to paint
    int initdelay=5;						// # cycles to wait before redrawing
/* Offscreen graphics context for double buffering */
    Graphics offScrGC;
/* The offscreen image used in double buffering */
    Image offScrImage;


    public void init() {
     
//	setSize(maxwidth, maxheight);				// set window size to specified limits
	maxwidth = getSize().width;
	maxheight = getSize().height;
	setBackground(Color.white);
	r = 255;						// set default color
	gr = 0;
	b = 0;

/* read in the parameters from HTML file */
	if (getParameter("delay") != null)
	{
	    delay = Integer.valueOf(getParameter("delay")).intValue();
	}


/* Add the mouse and mouse motion listeners */
	addMouseMotionListener(this);
	addMouseListener(this);

    }								// end of init


/** operate the main thread here */
    public void run() {
	Random rn = new Random();				// create a random number generator

	Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
	while (runit)						// begin thread loop
	{
	    if (animgo) {					// check the animation flag
		c1 += c1addto;
		if (c1 > 0.4) c1 = 0.0;				// reset at the useable limit
		repaint();					// repaint the window
		try { Thread.currentThread().sleep(delay);	// implement delay to slow things down
		}
		    catch (Exception e) { };
	    }							// end check on animation flag
	}							// end thread loop

    }								// end of run


/** override default paint - check for initial delay satisfied */
    public void paint(Graphics g) {
	double scale=100.0;
	double xoff=1.0*scale;
	double yoff=2.5*scale;

	setBackground(Color.white);
//	animgo = false;						// only draw once, don't update

/* draw the Ikeda attractor   */

//   first set the constants determining the curve
	double c2=0.9;
	double c3=6.0;
	double rho=1.0;
	double x=0.1;
	double y=0.1;
	for (int i=1; i<npts; i++)			// loop over all points on the attractor
	{
	    double temp = c1 - c3/(1.0 + x*x + y*y);
	    double sintemp = Math.sin(temp);
	    double costemp = Math.cos(temp);
	    double xt = rho + c2*(x*costemp - y*sintemp);
	    y = c2*(x*sintemp + y*costemp);
	    x = xt;
	    int j = (int)(x*scale + xoff);
	    int k = (int)(y*scale + yoff);
	    g.setColor(new Color(r, gr, b));
	    g.drawRect(j, k, 1, 1);
	}
    }							// end of paint


/** Update without erasing the background */
    public void update(Graphics g) {

	if (initcnt > initdelay)			// check for counter past delay period
	{

/* provide for double-buffered animation */
	    if (offScrImage == null)
	    {
		offScrImage = createImage(getSize().width, getSize().height);
		offScrGC = offScrImage.getGraphics();
	    }

/* now fill in the buffer with background color to cover over previous image */
	    offScrGC.setColor(getBackground());
	    offScrGC.fillRect(0,0,getSize().width, getSize().height);
	    offScrGC.setColor(getForeground());

/* call paint to fill in the picture in the off screen buffer, then xfer buffer to screen */
	    paint(offScrGC);
	    g.drawImage(offScrImage, 0, 0, null);
	} else {					// if not past delay, bump the counter
	    initcnt++;
	}						// end check for delay period
    }							// end of update




/** start up the animation thread */
    public void start() {
	if (kicker == null) {
	    kicker = new Thread(this);
	    kicker.start();
	}
    }


/** stop the animation thread */
    public void stop() {
	if (kicker != null) {
	    kicker.stop();
	    kicker=null;
	}
    }


/** Sets the animation counter */
    public void setAnimationCounter(int cntval) {
	xbmp = cntval;
    }


/** documentation methods */
    public String getAppletInfo() {
	return "Ikeda by Larry Gladney ";
    }



    public String[][] getParameterInfo() {
	String [][] info = {
	{"delay      ","int        ", "get delay factor for animation in msec"},
	};
	return info;
    }


    public void mouseReleased(MouseEvent e) {

    }


    public void mouseMoved(MouseEvent evt) {

    }


    public void mousePressed(MouseEvent evt) {

    }


    public void mouseDragged(MouseEvent e) {

    }

    public void mouseEntered(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }

    public void mouseClicked(MouseEvent evt) {

	evt.consume();					// we are handling this event here
	animgo = true;
	if (r == 255)					// shift the current color scheme
	{
	    r = 150;
	    gr = 150;
	    b = 0;
	} else if (r == 150) {
	    r = 180;
	    gr = 0;
	    b = 180;
	} else {
	    r = 255;
	    gr = 0;
	    b = 0;
	}						// end check for current color scheme

	repaint();
    }

}