/*
 * df5.java - revised 20 Dec 2010 - width 321, height 241
 * @author jackord@kw.igs.net
 * X-ray diffraction patterns for cubic crystals generated by superimposing
 *   Huygens' wavelets from an nxnxn array of single atoms (SC) or a basis of
 *   two (BCC) or four (FCC) atoms, where n can be scanned from = 2 to 1024
 *   or set to 256.
 * The wavelength can be chosen to enhance diffraction from
 *   (111), (201), or (211) planes.
 */

import java.applet.Applet;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class df5 extends Applet 
                  implements ActionListener {
  int kk=0; int first=0;                               // Declarations
  String tst;
  String b1s="SC"; Button b1=new Button(b1s);
  String b2s="BCC"; Button b2=new Button(b2s);
  String b3s="FCC"; Button b3=new Button(b3s);
  Choice chla=new Choice();
  CheckboxGroup chg=new CheckboxGroup();
  Checkbox[] ch=new Checkbox[2];
  CheckboxGroup cgg=new CheckboxGroup();
  Checkbox[] cg=new Checkbox[2];
  Image bim;
  Graphics bgr;

  public void init() {
    add(b1); b1.addActionListener(this);
    add(b2); b2.addActionListener(this);
    add(b3); b3.addActionListener(this);
    chla.addItem("la=2a/3"); chla.addItem("la=2a/5");
    chla.addItem("la=2a/6");
    add(chla);
    chla.select(0);
    add(ch[0]=new Checkbox("Transmit", chg, true));
    add(ch[1]=new Checkbox("Reflect", chg, false));
    add(cg[0]=new Checkbox("Scan n", cgg, true));
    add(cg[1]=new Checkbox("n=256", cgg, false));
    setBackground(new Color(211, 211, 211));
    chla.setBackground(getBackground());
    ch[0].setBackground(getBackground());
    ch[1].setBackground(getBackground());
    cg[0].setBackground(getBackground());
    cg[1].setBackground(getBackground());
    setFont(new Font("TimesRoman", Font.PLAIN, 12));
  }

  public void paint(Graphics g) {                      // Main Program
    b1.setBounds(10, 2, 60, 20);
    b2.setBounds(10, 25, 60, 20);
    b3.setBounds(10, 48, 60, 20);
    ch[0].setBounds(5, 73, 70, 20);
    ch[1].setBounds(5, 98, 70, 20);
    cg[0].setBounds(5, 123, 70, 20);
    cg[1].setBounds(5, 148, 70, 20);
    chla.setBounds(5, 173, 70, 20);
    int c, di, ni, n1, n2, x0, y0, del; long tt;
    double a, b, d, z, zz, r0, qr, qi, rr, ri, sr, si, t, sc, sn;
    double [] la=new double[3];
    if (first==0) {
      bim=createImage(240, 240);
      bgr=bim.getGraphics();
      first=1;
    }
    a=3.615E-7; x0=120; y0=120; z=30.; zz=z*z;         // Cu lattice parameter
    la[0]=2*a/3; la[1]=2*a/5; la[2]=2*a/6;
    double pi=Math.PI;
    g.setColor(Color.black);                           // Initial screen
    g.drawRect(0, 0, 320, 240);
    if (cg[0].getState()==true) { n1=1; n2=10; } else { n1=8; n2=n1; }
    if (ch[0].getState()==true) di=1; else di=-1;      // Transmit / Reflect
    if (kk>0) {                                        // Default Simple Cubic
      for (int n=n1; n<=n2; n=n+1) {
        for (int ny=-120; ny<=120; ny=ny+1) {          // Screen Y loop
          for (int nx=-120; nx<=120; nx=nx+1) {        // Screen X loop
            r0=Math.sqrt(zz+nx*nx+ny*ny);
            b=2*pi*a/r0/la[chla.getSelectedIndex()];
            sr=1; si=0; ni=1; sn=1.0;
            if (kk==2) {                               // Body-Centred Cubic
              t=b/2*(nx+ny+di*z-r0);
              rr=Math.cos(t); ri=Math.sin(t);
              qr=sr+rr*sr-ri*si; si=si+rr*si+ri*sr;
              sr=qr;
            }
            if (kk==4) {                               // Face-Centred Cubic
              t=b/2*(nx+ny);
              rr=Math.cos(t); ri=Math.sin(t);
              qr=sr+rr*sr-ri*si; qi=si+rr*si+ri*sr;
              t=b/2*(nx+di*z-r0);
              rr=Math.cos(t); ri=Math.sin(t);
              qr=qr+rr*sr-ri*si; qi=qi+rr*si+ri*sr;
              t=b/2*(ny+di*z-r0);
              rr=Math.cos(t); ri=Math.sin(t);
              qr=qr+rr*sr-ri*si; qi=qi+rr*si+ri*sr;
              sr=qr; si=qi;
            }
            for (int i=1; i<=n; i=i+1) {               // Array X loop
              t=b*ni*nx;
              rr=Math.cos(t); ri=Math.sin(t);
              qr=sr+rr*sr-ri*si; si=si+rr*si+ri*sr;
              sr=qr; ni=2*ni; sn=2*sn;
            }
            ni=1;                                      // Array Y loop
            for (int i=1; i<=n; i=i+1) {                 
              t=ni*b*ny;
              rr=Math.cos(t); ri=Math.sin(t);
              qr=sr+rr*sr-ri*si; si=si+rr*si+ri*sr;
              sr=qr; ni=2*ni; sn=2*sn;
            }
            ni=1;
            for (int i=1; i<=n; i=i+1) {               // Array Z loop 
              t=ni*b*(di*z-r0);
              rr=Math.cos(t); ri=Math.sin(t);
              qr=sr+rr*sr-ri*si; si=si+rr*si+ri*sr;
              sr=qr; ni=2*ni; sn=2*sn;
            }
            sc=2550/sn/sn/kk/kk;                        // Intensity scale
            c=(int)((sr*sr+si*si)*sc);
            if (c>255) { c=255; }                        
            Color col=new Color(0, c, 0);
            bgr.setColor(col);
            bgr.drawLine(x0+nx, y0-ny, x0+nx, y0-ny);  // Plot intensity
          }
        }
        bgr.setColor(Color.white);
        bgr.drawString(tst+"   n = "+(int)(Math.pow(2, n)), 5, 235);
        g.drawImage(bim, 80, 0, null);                 // Show plot buffer
        tt=System.currentTimeMillis();
      while ((System.currentTimeMillis()-tt)<1000) { }
      }
    }
    kk=0;
  }

  public void actionPerformed(ActionEvent e) {         // Buttons
    tst=e.getActionCommand();
    if (b1s.equals(tst)) { kk=1; }
    if (b2s.equals(tst)) { kk=2; }
    if (b3s.equals(tst)) { kk=4; }
    repaint();
  }
}