/* large (1000x1000) FDTD 2D   */
/* coded by Ikeuchi Mitsuru    */
/* ver 0.0.1   2005.02.12      */

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

public class largeFDTD2D extends Applet
  implements MouseListener, MouseMotionListener,
    ItemListener, ActionListener, AdjustmentListener, Runnable {

/* -------------------------------------- set global ------ */

  Choice ch_view;
  Button bt_reset, bt_start, bt_stop;
  Scrollbar sc_lambda, sc_magnitude;

  Thread th = null;

  Dimension dim;
  Image imgOff;
  Graphics gOff;

  int sleepTime = 50;

  int dispMode = 0;
  int started = 1;
  double magn = 1.0;
  double omega = Math.PI/100.0;
  double theta = 0.0;


  double t = 0.0;
  double dt = 1.0;

  int NNx = 1001;
  int NNy = 1001;

  double Ez[][] = new double[NNx+1][NNy+1];
  double Hx[][] = new double[NNx+1][NNy+1];
  double Hy[][] = new double[NNx+1][NNy+1];

  double ep[][] = new double[NNx+1][NNy+1];
  double mu[][] = new double[NNx+1][NNy+1];
  double sg[][] = new double[NNx+1][NNy+1];
  int metal[][] = new int[NNx+1][NNy+1];

  int dgX, dgY, dgXb,dgYb;

  double viewTheta = -15.0*3.14/180.0;
  double viewFai = -60.0*3.14/180.0;
  double dtheta = 0.0*3.14/180.0;
  double pai = 3.1415926536;

  double cosTh = Math.cos(viewTheta); 
  double sinTh = Math.sin(viewTheta);
  double cosFi = Math.cos(viewFai);
  double sinFi = Math.sin(viewFai);

  int NN = NNx+2;
  int xpts[] = new int[NN];
  int ypts[] = new int[NN];

/* ----------------------------- applet control ------ */

  public void init() {

    resize(630,450);
    setBackground(Color.white);

    dim = getSize();
    imgOff = createImage(dim.width,dim.height);
    gOff = imgOff.getGraphics();

    ch_view = new Choice();
    ch_view.addItem("Ez grid"); ch_view.addItem("Ez dens");
	ch_view.addItem("Hxy vector"); ch_view.addItem("Ez & Hxy");
    ch_view.addItemListener(this); 

    bt_reset= new Button("reset");
    bt_reset.addActionListener(this);

    bt_start= new Button("start");
    bt_start.addActionListener(this);
 
    bt_stop = new Button("stop");
    bt_stop.addActionListener(this);

    sc_lambda= new Scrollbar(Scrollbar.HORIZONTAL,100,10,16,210);
    sc_lambda.addAdjustmentListener(this);

    sc_magnitude= new Scrollbar(Scrollbar.HORIZONTAL,100,10,1,210);
    sc_magnitude.addAdjustmentListener(this);

    addMouseListener(this);  
    addMouseMotionListener(this);

    setLayout(new BorderLayout());
    Panel pnl = new Panel();
    pnl.setLayout(new GridLayout(1,6,5,0));
    pnl.add(bt_reset);
    pnl.add(bt_start);
    pnl.add(bt_stop);
    pnl.add(sc_lambda);
    pnl.add(sc_magnitude);
    pnl.add(ch_view);
    add(pnl,"North");

    setInitialCondition();
  }

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

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


  public void itemStateChanged(ItemEvent ev){
    if (ev.getSource() == ch_view){
      dispMode = ch_view.getSelectedIndex();
      repaint(); 
    }
  }

  public void actionPerformed(ActionEvent ev){
    if(ev.getSource() == bt_reset){
      started = 0;
      setInitialCondition();
    } else if(ev.getSource() == bt_start){ 
      if (started==0) {
        started = 1;
      } else if (started==1) {
        theta = 0.0;
      }
    } else if(ev.getSource() == bt_stop){
      started = 0;
    }
  }


  public void adjustmentValueChanged(AdjustmentEvent ev){
    if (ev.getSource() == sc_lambda) { 
      omega = Math.PI/((double)sc_lambda.getValue());
    } else if(ev.getSource() == sc_magnitude) { 
      magn = 0.01*(double)(sc_magnitude.getValue());
    }
  }

  public void mousePressed(MouseEvent ev){ }
  public void mouseReleased(MouseEvent ev){
    dgXb = 0; dgYb = 0;
    dgX = 0; dgY = 0;
  }
  public void mouseClicked(MouseEvent ev){ }
  public void mouseEntered(MouseEvent ev){ } 
  public void mouseExited (MouseEvent ev){ }

  public void mouseMoved  (MouseEvent ev){ }

  public void mouseDragged(MouseEvent ev){
    dgXb = dgX; dgYb = dgY;
    dgX=ev.getX();
    dgY=ev.getY();
    if (dgXb==0 && dgYb==0) {
      dgXb = dgX; dgYb = dgY;
    }
    viewTheta += 0.5*3.14/180.0*(dgX-dgXb);
    viewFai += 0.5*3.14/180.0*(dgY-dgYb);
    cosTh = Math.cos(viewTheta); 
    sinTh = Math.sin(viewTheta);
    cosFi = Math.cos(viewFai);
    sinFi = Math.sin(viewFai);
  }


  public void run() {
    while (th != null) {
      try {
        timeEvolution();
        offPaint();
        repaint();
        Thread.sleep(sleepTime);
      } catch (InterruptedException e) { }
    }
  }

  public void update(Graphics g) {
    paint(g);
  }

  public void paint(Graphics g) {
    g.drawImage(imgOff,0,0,this);
  }

/* ----------------------------- offPaint -------------------- */

  void offPaint() {
    int gbx,gby;

    gOff.setColor(Color.white);
    gOff.fillRect(0,0,dim.width,dim.height);


    if (dispMode==0) {

      gridEzPlot();

    } else if (dispMode==1) {

      densityEzPlot();

    } else if (dispMode==2) {

      matPlot();
	  vectorHxyPlot();

    } else if (dispMode==3) {

      densityEzPlot();
	  vectorHxyPlot();

    }


    gOff.setColor(Color.black);
    gOff.drawString("t="+(int)(t)+" ",630/6*0+10,40);
    gOff.drawString("lambda="+(int)(Math.PI/omega+0.5)+" ",630/6*3+10,40);
    gOff.drawString("magn="+(int)(magn*100.0+0.5)+"%",630/6*4+10,40);
    gOff.drawString("view",630/6*5+10,40);

    gbx = 530; gby = 360;
    gOff.setColor(Color.green);
    gOff.drawString("vaccum",gbx,gby);
    gOff.setColor(Color.orange);
    gOff.drawString("metal",gbx,gby+15);
    gOff.setColor(Color.red);
    gOff.drawString("dielectrics",gbx,gby+30);
    gOff.setColor(Color.blue);
    gOff.drawString("ferromagnetic",gbx,gby+45);
    gOff.setColor(Color.magenta);
    gOff.drawString("diele+ferro",gbx,gby+60);
    gOff.setColor(Color.gray);
    gOff.drawString("resistor",gbx,gby+75);
/*
    gOff.drawString("theta="+(int)(viewTheta*180.0/3.14)+" ",gbx,210);
    gOff.drawString("fai="+(int)(viewFai*180.0/3.14)+" ",gbx,230);
*/
  }

/* ----------------------------- plot method ------ */

  void gridEzPlot() {
    int i,j;
    int cx,cy,cz,gbx,gby;
    double z,px,py,pz,sc,scrVar;

    cx = NNx/2;
    cy = NNy/2;
    cz = 0;
    sc = 0.5;
    scrVar = 30.0*magn;

    gbx = -940+(int)(cx/sc);
    gby = -1000+(int)(cy/sc);

    for(j=0; j<NNy; j += 16) {
      for (i=0; i<NNx; i+=4) { 
        z = scrVar*Ez[i][j]+cz;
        py = cosFi*(j-cy)+sinFi*(z-cz) + cy; 
        pz = -sinFi*(j-cy)+cosFi*(z-cz) + cz;
        px = cosTh*(i-cx)+sinTh*(pz-cz) + cx; 
        pz = -sinTh*(i-cx)+cosTh*(pz-cz) + cz;
        xpts[i] = (int)(sc*px)+gbx;
        ypts[i] = (int)(sc*py)+gby;
      }
      for (i=0; i<NNx-2; i+=4) {
        if (sg[i][j]>0.0) {
          gOff.setColor(Color.getHSBColor((float)colorOf(i,j),0.9f,0.5f));
        } else {
          gOff.setColor(Color.getHSBColor((float)colorOf(i,j),0.9f,0.9f));
        }
        gOff.drawLine(xpts[i],ypts[i],xpts[i+4],ypts[i+4]);
      }
    }

    for(i=0; i<NNx; i += 16) {
      for (j=0; j<NNy; j+=4) { 
        z = scrVar*Ez[i][j]+cz;
		py = cosFi*(j-cy)+sinFi*(z-cz) + cy; 
        pz = -sinFi*(j-cy)+cosFi*(z-cz) + cz;
        px = cosTh*(i-cx)+sinTh*(pz-cz) + cx; 
        pz = -sinTh*(i-cx)+cosTh*(pz-cz) + cz;
        xpts[j] = (int)(sc*px)+gbx;
        ypts[j] = (int)(sc*py)+gby;
      }
      for (j=0; j<NNy-2; j+=4) { 
        if (sg[i][j]>0.0) {
          gOff.setColor(Color.getHSBColor((float)colorOf(i,j),0.9f,0.5f));
        } else {
          gOff.setColor(Color.getHSBColor((float)colorOf(i,j),0.9f,0.9f));
        }
        gOff.drawLine(xpts[j],ypts[j],xpts[j+4],ypts[j+4]);
      }
    }
  }


  void densityEzPlot() {
    int i,j,gbx,gby,h;
    double sc;

    gbx = 30;
    gby = 60;
 
    h = 3;
    for(j=0; j<NNx; j += 8) {
      for (i=0; i<NNy; i += 8) { 
        gOff.setColor(Color.getHSBColor( (float)colorOf(i,j),
          (float)(0.3+0.6/(30.0*sg[i][j]+1.0)),(float)(0.5+0.25*Ez[i][j])));
        gOff.fillRect(i*h/8+gbx,j*h/8+gby,h,h);
      }
    }
  }

  void vectorHxyPlot() {
    int i,j,gbx,gby,ii,jj,h;
    double sc;

    gbx = 30;
    gby = 60;
	
    gOff.setColor(Color.red);
    for(i=0; i<NNx-2; i += 16) {
	  ii = gbx + i*3/8 + 3;
      for (j=0; j<NNy-2; j += 16) {
	    jj = gby + j*3/8 + 3;
        gOff.drawLine(ii,jj,ii+(int)(15.0*magn*Hx[i][j]),jj+(int)(15.0*magn*Hy[i][j]));
      }
    }
  }

  void matPlot() {
    int i,j,gbx,gby,h;
    double sc;

    gbx = 30;
    gby = 60;
 
    h = 3;
    for(j=0; j<NNx; j += 8) {
      for (i=0; i<NNy; i += 8) {
	    if (colorOf(i,j)!=0.33) {
          gOff.setColor(Color.getHSBColor( (float)colorOf(i,j),
            (float)(0.3+0.6/(30.0*sg[i][j]+1.0)),(float)(0.5+0.25*Ez[i][j])));
          gOff.fillRect(i*h/8+gbx,j*h/8+gby,h,h);
		}
      }
    }
  }

 double colorOf(int ix, int iy) {
    double c;

    c = 0.33;
    if (metal[ix][iy]==0) {
      c = 0.33;
      if (ep[ix][iy]>1.0) {
        if (mu[ix][iy]>1.0) {
          c = 0.85;
        } else {
          c = 0.01;
        }
      } else {
        if (mu[ix][iy]>1.0) {
          c = 0.66;
        }
	  }
      if (sg[ix][iy]>0.0) {
        c = c-0.05;
      }
    } else {
      c = 0.12;
    }
    return ( c );
 }

/* ----------------------------- set initial condition ------ */

  void setInitialCondition() {

    t = 0.0;
    theta = 0.0;
    clearField();
    setMaterial();

  }

  void clearField() {
    int i,j;

    for(i=0;i<NNx+1;i++) {
      for(j=0;j<NNy+1;j++) {
       	Ez[i][j] = 0.0;
       	Hx[i][j] = 0.0;
       	Hy[i][j] = 0.0;
      }
    }
  }

  void setMaterial() {
    int i,j,ix,iy;

    for(i=0;i<NNx+1;i++) {
      for(j=0;j<NNy+1;j++) {
       	ep[i][j] = 1.0;
       	mu[i][j] = 1.0;
       	sg[i][j] = 0.0;
       	metal[i][j] = 0;
      }
    }

    setRect(200,  50, 200, 150, 3.0, 1.0, 0.0, 0);
    setRect(200, 250, 200, 150, 1.0, 4.0, 0.0, 0);
    setRect(200, 450, 200, 150, 1.0, 1.0, 0.05, 0);
	setRect(200, 650, 200, 150, 1.0, 1.0, 0.0, 1);

  }

  void setRect(int ix, int iy, int xSize, int ySize, double epMat, double muMat, double sgMat, int metalMat) {
    int i,j;

    for(i=0;i<xSize;i++) {
      for(j=0;j<ySize;j++) {
       	ep[ix+i][iy+j] = epMat;
       	mu[ix+i][iy+j] = muMat;
       	sg[ix+i][iy+j] = sgMat;
       	metal[ix+i][iy+j] = metalMat;
      }
    }
  }

/* ----------------------------- fdtd method 2D -------------- */

  void timeEvolution() {
    int i;

    if (started==1) {
	  for(i=0;i<10;i++) {
        fdtd2D();
      }
    }
  }

  void fdtd2D() {

    t = t + 0.5*dt;
    EzEvolution();
    EzGenerator();
    HxyEvolution();
  }

  void EzGenerator() {
    int j;
    double Ezt;

    theta += omega*0.5*dt;
    Ezt = Math.sin(theta);
    if (theta<3.1416*2.0) {
      for(j=0;j<NNy;j++) {
        Ez[0][j]=Ezt;
      }
    }

  }

  void EzEvolution() {
    int i,j;
    double sqrt2v2,d2;

    sqrt2v2 = 0.70710678/2.0;
    d2 = dt*0.5;

    for(i=0;i<NNx;i++) {
      for(j=0;j<NNy;j++) {
        if (metal[i][j]==0) {
         	Ez[i][j] += (-sg[i][j]*d2*Ez[i][j] + 
            (sqrt2v2/ep[i][j])*((Hy[i+1][j]-Hy[i][j])-(Hx[i][j+1]-Hx[i][j])));
        }
      }
    }
  }


  void HxyEvolution() {
    int i,j;
    double sqrt2v2,c;

    sqrt2v2 = 0.70710678/2.0;
    c = (1.0-sqrt2v2)/(1.0+sqrt2v2);

    for(i=0; i<NNx; i++) {
      Hx[i][0] = c*Hx[i][0] + Hx[i][1];
    }
    for(i=0; i<NNx; i++) {
      Hx[i][NNy] = c*Hx[i][NNy] + Hx[i][NNy-1];
    }
    for(j=0; j<NNy; j++) {
      Hy[0][j] = c*Hy[0][j] + Hy[1][j];
    }
    for(j=0; j<NNy; j++) {
      Hy[NNx][j] = c*Hy[NNx][j] + Hy[NNx-1][j];
    }

    for(i=0;i<NNx;i++) {
      for(j=1;j<NNy;j++) {
       	Hx[i][j] -= sqrt2v2/mu[i][j]*(Ez[i][j]-Ez[i][j-1]);
      }
    }

    for(i=1;i<NNx;i++) {
      for(j=0;j<NNy;j++) {
       	Hy[i][j] += sqrt2v2/mu[i][j]*(Ez[i][j]-Ez[i-1][j]);
      }
    }

    for(i=0;i<NNx;i++) {
      Hx[i][0] -= c*Hx[i][1];
    }
    for(i=0;i<NNx;i++) {
      Hx[i][NNy] -= c*Hx[i][NNy-1];
    }
    for(j=0;j<NNy;j++) {
      Hy[0][j] -= c*Hy[1][j];
    }
    for(j=0;j<NNy;j++) {
      Hy[NNx][j] -= c*Hy[NNx-1][j];
    }
  }

/* ----------------------------- end of applet -------------- */

}