// Superposition2.Applet  (JDK 1.0)
//
/*************************************************************************
 *                                                                       *
 * Copyright (c) 1998         Greg W. Anderson                           *
 *                                                                       *
 * This program is free software.  You can copy, modify, or redistribute *
 * this software under the terms of the GNU General Public License       *
 * as published by the Free Software Foundation; either version 2 of the *
 * License, or (at your option) any later version, provided that both    *
 * the above copyright notice appears in all copies and that this        *
 * permission notice appear in any supporting documentation.             *
 *                                                                       *
 * This software is provided "as is" in the hope that it will be useful, *
 * but WITHOUT any expressed or implied warranty of merchantability or   *
 * fitness for any particular purpose.  Your milage may vary.            * 
 * See the GNU General Public License for more details.                  *
 *                                                                       *
 *************************************************************************/

//  Modification History
//    Date      Initials     Change
//    2/01/98    GWA         Initial release
//  Abstract:
/*
 * the amplitude and angular frequency of two simple
 * harmonic waves.  This is built over various classes
 * from SUN's JDK. 
 * @author Greg Anderson
 * @version 0.1, 21 Feb 1998
 */

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


public class Superposition2 extends java.applet.Applet implements Runnable{

  Superposition2Controls controls;
  Superposition2Canvas c;
  Superposition2Banner banner;

  Label appletName  = new Label ("The Virtual Physics Laboratory");
  Label department  = new Label ("Department of Physics and Astronomy");
  Label university = new Label ("Northwestern University");

  public void init(){
    
    setLayout(new BorderLayout());
    c = new Superposition2Canvas();
    
    banner =  new Superposition2Banner (2,2);
    banner.add("Center",department);
    banner.add(appletName);
    banner.add("Center",university);
    banner.add("South", new Label ("G.Anderson"));
    
    add ("North",banner);
    add("Center",c);
    add("South", controls = new Superposition2Controls(c));
    c.annimationThread = null;
    c.stopAnnimation = false; 
  }
  
  
  public void run(){
    while (c.annimationThread != null){
      try {Thread.sleep(300);} catch (InterruptedException e){}
      c.repaint();
    }
    c.annimationThread = null;
  }
  public void start(){
    controls.enable();
    if (c.annimationThread == null){
      c.annimationThread = new Thread(this);
      c.annimationThread.start();
    }
  }
  
  
  public void stop(){
    controls.disable();
    c.offg = null;
    c.offImage = null;
  }
  
  public boolean handleEvent(Event e){
    if (e.id == Event.WINDOW_DESTROY){
      System.exit(0);
    }
    return false;
  }
}

class Superposition2Canvas extends Canvas {


  Dimension offDimension;      // These objects are used for
  Image offImage;              // Double Buffering to 
  Graphics offg;                 // "offline graphics"
  
  Thread annimationThread;
  boolean stopAnnimation; 

  int halfWidth = 200;
  
  int spacing = 30;
  int shiftr  = 25;
  int vcenter1 = 3*spacing;         /* Vertical Center for graph 1 */
  int vcenter2 = 6*spacing;         /* Vertical Center for graph 1 */
  int vcenter3 = 10*spacing;        /* Vertical Center for graph 1 */

  int t = 0;
  double v1;             /*  v = f*lambda = w/k */
  double v2;           
  double vc;             /* carrier or phase velocity */
  double vg;             /* group velocity            */
  double k1 = 0.5;       /* k = w/v                   */
  double k2 = 0.45;      /* k = 2pi/lambda            */
  double w1 = 1.0;       /* angular frequencies       */  
  double w2 = 0.7;        
  
  int A0 = 30;        /* Amplitude */
  int A1 = A0;        /* Amplitude */
  int A2 = A0;        /* Amplitude */
  int A3 = A0;        /* Amplitude */
  
  // The displacement plotted is actually measured from
  // the top of the screen downward, hence the -A1 etc 
  // below.

  double fun1(double x) {
    return ( -A1*Math.sin(k1*x - w1*t)  + vcenter1 );
  }
  
  double fun2(double x) {
    return ( -A2*Math.sin(k2*x - w2*t)  + vcenter2);
  }
  
  double fun(double x) { 
    return ( fun1(x) + fun2(x) + vcenter3 - vcenter2 - vcenter1);
  }
  
  static String firstWave    = "A1(x,t) = A0_1*sin(k1*x - w1*t):";
  static String secondWave   = "A2(x,t) = A0_2*sin(k2*x - w2*t):";
  static String combinedWave = "A(x,t) = A1(x,t) + A2(x,t):";
  
  public void paint(Graphics g) {
    update(g);
  }
  
  public void update(Graphics g) {
    
    Dimension d = size();      //onscreen drawing area:
    if ( (offg == null)
	 || (d.width != offDimension.width)
	 || (d.height != offDimension.height) ) {
      offDimension = d;
      offImage = createImage(d.width, d.height);
      offg = offImage.getGraphics();
    }
    
    //Erase the previous image.
    offg.setColor(getBackground());
    offg.fillRect(0, 0, d.width, d.height);
    
    setBackground(Color.white);
    Color darkmagenta = new Color(150,0,150);
    
    /*  axes */
    offg.setColor(Color.gray);
    offg.drawLine(shiftr,vcenter1,size().width,vcenter1);
    offg.drawLine(shiftr,vcenter2,size().width,vcenter2);
    offg.drawLine(shiftr,vcenter3,size().width,vcenter3);
    A3 = abs(A1) + abs(A2);
    offg.drawLine(shiftr,vcenter1 -12*A1/10, shiftr,vcenter1 + 12*A1/10);
    offg.drawLine(shiftr,vcenter2 -12*A2/10, shiftr,vcenter2 + 12*A2/10);
    offg.drawLine(shiftr,vcenter3 -12*A3/10, shiftr,vcenter3 + 12*A3/10);
    
    /*  axis labels */
    offg.setColor(Color.darkGray);
    offg.drawString("  20",0,vcenter1-15);
    offg.drawString("   0",0,vcenter1+ 5);
    offg.drawString("-20",0,vcenter1+25);
    offg.drawString("x",size().width-15,vcenter1+10);
    offg.drawString("  20",0,vcenter2-15);
    offg.drawString("   0",0,vcenter2+ 5);
    offg.drawString("-20",0,vcenter2+25);
    offg.drawString("x",size().width-15,vcenter2+10);
    offg.drawString("  20",0,vcenter3-15);
    offg.drawString("   0",0,vcenter3+ 5);
    offg.drawString("-20",0,vcenter3+25);
    offg.drawString("x",size().width-15,vcenter3+10);
    
    
    offg.drawString(firstWave,shiftr+5, vcenter1 - 12*spacing/10);
    v1 = w1/k1;
    offg.drawString("v_1 = " + v1, halfWidth+100, vcenter1 - 12*spacing/10);
    
    offg.drawString(secondWave,shiftr+5, vcenter2 - 12*spacing/10);
    v2 = w2/k2;
    offg.drawString("v_2 = " + v2, halfWidth+100, vcenter2 - 12*spacing/10);
    
    
    offg.drawString(combinedWave,shiftr+5, vcenter3 - 24*spacing/10);
    vc = (w1 + w2)/(k1 + k2) ;
    vg = (w1 - w2)/(k1 - k2) ;
    offg.drawString("v_ph = " + vc, halfWidth+50, vcenter3 - A3 - 18);
    offg.drawString("v_g  =  " + vg, halfWidth+50, vcenter3 - A3 - 5);
    
    offg.setColor(darkmagenta);
    int sn;
    for (int n = 0 ; n < size().width - shiftr; n++) {
      sn = n + shiftr;
      offg.drawLine(sn,(int)fun1(n),sn+1,(int)fun1(n+1));
    }   
    
    offg.setColor(Color.blue);
    for (int n = 0 ; n < size().width - shiftr ; n++) {
      sn = n + shiftr;
      offg.drawLine(sn,(int)fun2(n),sn+1,(int)fun2(n+1));
    }
    offg.setColor(Color.red);
    for (int n = 0 ; n < size().width -shiftr; n++) {
      sn = n + shiftr;
      offg.drawLine(sn,(int)fun(n),sn+1,(int)fun(n+1));
    }
    
    g.drawImage(offImage, 0, 0, this); 
    
    t++;
  }
  
  public static int abs(int a){
    return (a < 0) ? -a : a;
  }
  
  public static double fabs(double a){
    return (a < 0) ? -a : a;
  }

  public void redraw(Double W1, Double W2,
		     Double K1, Double K2,
		     Double a1, Double a2){
    w1 = W1.doubleValue();
    w2 = W2.doubleValue();
    k1 = K1.doubleValue();
    k2 = K2.doubleValue();
    A1 = a1.intValue();
    A2 = a2.intValue();
    repaint();
  }
  
  public boolean mouseDown(java.awt.Event evt, int x, int y) {
    if (stopAnnimation) {
      annimationThread.resume();
    }
    else {
      annimationThread.suspend();
    }
    stopAnnimation = !stopAnnimation;
    return true;
  }
}



class Superposition2Controls extends Panel{
  
  Button btemp;
  TextField w1;
  TextField w2;
  TextField k1;
  TextField k2;
  TextField a1;
  TextField a2;
  Superposition2Canvas canvas;

  public Superposition2Controls(Superposition2Canvas canvas){
    setLayout(new GridLayout(3,5,5,5));  /* nr,nc, vg, hg */
    this.canvas = canvas;
    Color darkmagenta = new Color(150,0,150);

    this.setForeground(Color.black);

    add (new Label("A. Frequencies:",Label.LEFT));

    btemp = new Button("W1 = ");
    btemp.setForeground(darkmagenta);
    add (btemp);
    add (w1 = new TextField("1.0",4));

    btemp = new Button("W2 = ");
    btemp.setForeground(Color.blue);
    add (btemp);
    add (w2 = new TextField("0.7",4));

    add (new Label("Wave Numbers:",Label.LEFT));

    btemp = new Button("k1 = ");
    btemp.setForeground(darkmagenta);
    add (btemp);
    add (k1 = new TextField("0.5",4));

    btemp = new Button("k2 = ");
    btemp.setForeground(Color.blue);
    add (btemp);
    add (k2 = new TextField("0.45",4));

    add (new Label("Amplitudes:",Label.LEFT));

    btemp = new Button("A0_1 = ");
    btemp.setForeground(darkmagenta);
    add (btemp);
    add (a1 = new TextField("30",4));

    btemp = new Button("A0_2 = ");
    btemp.setForeground(Color.blue);
    add (btemp);
    add (a2 = new TextField("30",4));
  }

  public boolean action(Event ev, Object arg){
    if(ev.target instanceof Button     // Redispla on Button click
       || ev.id == ev.END   ){         // Redisplay if Return
      String label = (String)arg;
      canvas.redraw(Double.valueOf( w1.getText().trim() ),
		    Double.valueOf( w2.getText().trim() ),
		    Double.valueOf( k1.getText().trim() ),
		    Double.valueOf( k2.getText().trim() ),
		    Double.valueOf( a1.getText().trim() ),
		    Double.valueOf( a2.getText().trim() )
		    );
      return true;
    }
    return false;
  }  
}

class Superposition2Banner extends Panel{  
  public Superposition2Banner(int n, int m){
    Color darkMagenta = new Color(150,0,150);
    setBackground(darkMagenta);
    setForeground(Color.white);
    setLayout(new GridLayout(n,m,40,-5));  /* nr,nc, vg, hg */
  }
}