/*_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/*
 *       (#)   Particle Orbit around Schwarzshild Black Hole                  *
 *                                                                            * 
 *                                    97/02/10   by T.Murauchi                *
 *_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/* 
 */
import java.applet.Applet;
import java.awt.*;

public class Particle extends Applet {

  static double re,se,alpha,r0,s0,vr0,vs0,dt0,tend0;
  static double pai,paideg,xe,ze,tend,rmax,rmax0,dt,x0,y0;
  static int mesh,nr;

  Panel inputpanel,controlpanel,checkpanel;
  Panel pre,pse,palpha,pr0,ps0,pvr0,pvs0,pdt0,ptend0;
  Label lre,lse,lalpha,lr0,ls0,lvr0,lvs0,ldt0,ltend0;
  TextField tre,tse,talpha,tr0,ts0,tvr0,tvs0,tdt0,ttend0;
  Checkbox axis,relative;
  Button calcu,res;
  Choice example;
  Particle_Canvas p_canvas;
  Title_Canvas  t_canvas;
  Variable_Canvas v_canvas;
  
  public void init() {

    re    = 25;
    se    = 0;
    alpha = 30;
    r0    = 10;
    s0    = 0;
    vr0   = 0;
    vs0   = 0.2;
    dt0   = 0;
    tend0 = 4;
    mesh  = 0;
    nr    = 0;
	
    setData();
  
    lre    = new Label("Re");
    lse    = new Label("Se");
    lalpha = new Label("Alpha");
    lr0    = new Label("R0");
    ls0    = new Label("F0");
    lvr0   = new Label("Vr0");
    lvs0   = new Label("Vs0");
    ldt0   = new Label("dt");
    ltend0 = new Label("END");
	
    tre    = new TextField("25",5);
    tse    = new TextField("0",5);
    talpha = new TextField("30",5);
    tr0    = new TextField("10",5);
    ts0    = new TextField("0",5);
    tvr0   = new TextField("0",5);
    tvs0   = new TextField("0.2",5);
    tdt0   = new TextField("0",5);
    ttend0 = new TextField("4",5);
	
    pre    = new Panel();
    pse    = new Panel();
    palpha = new Panel();
    pr0    = new Panel();
    ps0    = new Panel();
    pvr0   = new Panel();
    pvs0   = new Panel();
    pdt0   = new Panel();
    ptend0 = new Panel();
	
    pre.setLayout(new FlowLayout(FlowLayout.RIGHT));
    pse.setLayout(new FlowLayout(FlowLayout.RIGHT));
    palpha.setLayout(new FlowLayout(FlowLayout.RIGHT));
    pr0.setLayout(new FlowLayout(FlowLayout.RIGHT));
    ps0.setLayout(new FlowLayout(FlowLayout.RIGHT));
    pvr0.setLayout(new FlowLayout(FlowLayout.RIGHT));
    pvs0.setLayout(new FlowLayout(FlowLayout.RIGHT));
    pdt0.setLayout(new FlowLayout(FlowLayout.RIGHT));
    ptend0.setLayout(new FlowLayout(FlowLayout.RIGHT));
	
    pre.add(lre);            pre.add(tre);
    pse.add(lse);            pse.add(tse);
    palpha.add(lalpha);      palpha.add(talpha);
    pr0.add(lr0);            pr0.add(tr0);
    ps0.add(ls0);            ps0.add(ts0);
    pvr0.add(lvr0);          pvr0.add(tvr0);
    pvs0.add(lvs0);          pvs0.add(tvs0);
    pdt0.add(ldt0);          pdt0.add(tdt0);
    ptend0.add(ltend0);      ptend0.add(ttend0);
	
    inputpanel = new Panel();
    inputpanel.setLayout(new GridLayout(9,1));
    inputpanel.add(pre);
    inputpanel.add(pse);
    inputpanel.add(palpha);
    inputpanel.add(pr0);
    inputpanel.add(ps0);
    inputpanel.add(pvr0);
    inputpanel.add(pvs0);
    inputpanel.add(pdt0);
    inputpanel.add(ptend0);
	
    example = new Choice();
    example.addItem("example 1");
    example.addItem("example 2");
    example.addItem("example 3");
    example.addItem("example 4");
    example.addItem("example 5");
	
    calcu    = new Button("Calculate");
    res      = new Button("Reset");
    axis     = new Checkbox("Draw Coordinates Lattice");
    relative = new Checkbox("Ignore Relativistic Effect");
	
    checkpanel = new Panel();
    checkpanel.setLayout(new GridLayout(2,1));
    checkpanel.add(axis);
    checkpanel.add(relative);
	
    controlpanel = new Panel();
    controlpanel.setLayout(new FlowLayout(FlowLayout.CENTER));
    controlpanel.add(example);
    controlpanel.add(calcu);
    controlpanel.add(res);
    controlpanel.add(checkpanel);
    
    p_canvas = new Particle_Canvas();
    t_canvas = new Title_Canvas();
    v_canvas = new Variable_Canvas();
	
    p_canvas.setBackground(Color.black);
    t_canvas.setBackground(Color.orange);
    v_canvas.setBackground(Color.orange);
	
    t_canvas.resize(size().width,30);
    v_canvas.resize(250,size().height);
	
    setBackground(Color.orange);
    setLayout(new BorderLayout());
    add("Center",p_canvas);
    add("West",inputpanel);
    add("South",controlpanel);    
    add("North",t_canvas);       
    add("East",v_canvas);       
	
  }
  
  public boolean action(Event e, Object o) {

    String label = o.toString();
	
    if (e.target instanceof Button) {

      if (label.equals("Calculate")) {

        re    = Double.valueOf(tre.getText()).doubleValue();
        se    = Double.valueOf(tse.getText()).doubleValue();
        alpha = Double.valueOf(talpha.getText()).doubleValue();
        r0    = Double.valueOf(tr0.getText()).doubleValue();
        s0    = Double.valueOf(ts0.getText()).doubleValue();
       	vr0   = Double.valueOf(tvr0.getText()).doubleValue();
       	vs0   = Double.valueOf(tvs0.getText()).doubleValue();
        dt0   = Double.valueOf(tdt0.getText()).doubleValue();
        tend0 = Double.valueOf(ttend0.getText()).doubleValue();
		
        if (axis.getState() == true) {
          mesh = 1;
        } else { 
          mesh = 0;
   	}
		
   	if (relative.getState()  == true) {
          nr = 1;
        } else {
          nr = 0;
        }
		
        setData();
        p_canvas.repaint();
		
      } else {
	  
        example.select("example 1");
        setState("25","0","30","10","0","0","0.2","0","4",false,false);
		
      }
	  
    }
	
    if (e.target instanceof Choice) {

      if (label.equals("example 1")) {
        setState("25","0","30","10","0","0","0.2","0","4",false,false);
      }

      if (label.equals("example 2")) {
        setState("25","50","25","10","0","0","0.2","0","4",true,false);
      }

      if (label.equals("example 3")) {
        setState("10000","0","0.6","100","0","0","0.03","0","5",false,false);
      }

      if (label.equals("example 4")) {
        setState("10000","0","0.6","100","0","0","0.03","0","1",false,true);
      }

      if (label.equals("example 5")) {
        setState("25","0","9","3","0","0","0.577","0","7",false,false);
      }
	
	
    }

      return true;
		
  }	

  
  public void setState(String re,String se,String alpha,String r0,String s0,
                       String vr0,String vs0,String dt0,String tend0, 
                       boolean mesh,boolean nr) {

    tre.setText(re);
    tse.setText(se);
    talpha.setText(alpha);
    tr0.setText(r0);
    ts0.setText(s0);
    tvr0.setText(vr0);
    tvs0.setText(vs0);
    tdt0.setText(dt0);
    ttend0.setText(tend0);
    axis.setState(mesh);
    relative.setState(nr);
	
  }

  
  public void setData() {

// setData 1
    pai    = Math.PI;
    paideg = pai/180;  
    se     = se*paideg;
    xe     = re*Math.sin(se);
    ze     = re*Math.cos(se);
    alpha  = alpha*paideg;
    rmax   = re*Math.tan(alpha);
    rmax0  = 10;

    if (rmax > 1000) {
      rmax0 = 1000;
    } else { if (rmax > 100) { rmax0 = 100; }
    }
  
// setData 2 
    if (dt0 <= 0) {
      dt = Math.pow(r0,1.5)/10;
    } else {
      dt = dt0;
    }

    tend0 = tend0*pai*Math.pow(r0,1.5);
    tend  = tend0;

    if (tend0 <= 0) {
      tend0 = pai*Math.pow(r0,1.5); tend = tend0;
    }

    x0 = r0*Math.cos(s0);
    y0 = r0*Math.sin(s0);

  }

}


class Particle_Canvas extends Canvas {
  
  double pai,re,rmax,rmax0,R,Z;
  double dt,r,s,vr,vs;
  double xe,ze,x,y,z;
  double x0,y0,r0,t0;
  double s1rkg,s2rkg,s3rkg,s4rkg,s5rkg,s6rkg;
  double xrkg,zrkg,vrkg,hrkg;
  int mrkg; 

  double yrkg[] = new double[4];
  double frkg[] = new double[4];
  double brkg[] = new double[4];
  double crkg[] = new double[4];
  
  double fx(double X, double Y, double Z) {
    return re*Y*re/(re*re-xe*X-ze*Z);
  }

  double fy(double X, double Y, double Z) {
    return (xe*Z-ze*X)*re/(re*re-xe*X-ze*Z);
  }

  double gx(double phi, double R) {
    return R*Math.cos(phi);
  }

  double gy(double phi, double R) {
    return R*Math.sin(phi);
  }
  

  public void paint(Graphics g) {
  
    pai   = Particle.pai;
    rmax  = Particle.rmax;
    rmax0 = Particle.rmax0;
    re    = Particle.re;
    xe    = Particle.xe;
    ze    = Particle.ze;
    x0    = Particle.x0;
    y0    = Particle.y0;
    r0    = Particle.r0;
	
    s1rkg = 0.2928932188134527;
    s2rkg = 0.1213203435596426;
    s3rkg = 0.5857864376269054;
    s4rkg = 1.707106781186548;
    s5rkg = -4.121320343559643;
    s6rkg = 3.414213562373097;

    xrkg    = t0;                  
    yrkg[0] = r0;
    yrkg[1] = Particle.s0;
    yrkg[2] = Particle.vr0;
    yrkg[3] = r0*Particle.vs0;
    mrkg    = 1;
	
    Rectangle c  = bounds();
    double xrate = c.width/(2*rmax);
    double yrate = c.height/(2*rmax);
	
    g.setColor(new Color(13,100,219));
    for (int i = 0 ; i <= 2; i++) {
      g.drawRect(i,i,c.width-1-2*i,c.height-1-2*i);
    }

    for (int i = 1; i <=3; i++) {
      g.drawLine(i*c.width/4,0,i*c.width/4,c.height/40);
      g.drawLine(i*c.width/4,c.height,i*c.width/4,c.height-c.height/40-1);
      g.drawLine(0,i*c.height/4,c.width/40,i*c.height/4);
      g.drawLine(c.width,i*c.height/4,c.width-c.width/40-1,i*c.height/4);
    }
	
    g.setColor(Color.red);       
    R = 1; Z = 0;		   
    for (double phi = 0; phi <= 2*pai+pai/20; phi=phi+pai/20) {
      g.drawLine((int)((rmax+fx(gx(phi,R),gy(phi,R),Z))*xrate),
                 (int)((rmax-fy(gx(phi,R),gy(phi,R),Z))*yrate),
	         (int)((rmax-fx(gx(phi+pai/20,R),gy(phi+pai/20,R),Z))*xrate),
	         (int)((rmax-fy(gx(phi+pai/20,R),gy(phi+pai/20,R),Z))*yrate));
    }
	
	   
    if (Particle.mesh == 1) {               

      for (int i = 1; i <= 10; i++) {
        R = rmax0/10*i;
        if (R <= 1)  continue; 
        Z = 2*Math.sqrt(R-1);

        if (i%5 == 0) { 
          g.setColor(Color.pink); 
        } else {
          g.setColor(Color.lightGray);
       	}
	
        for (double phi = 0; phi <= 2*pai+pai/20; phi=phi+pai/20) {
          g.drawLine((int)((rmax+fx(gx(phi,R),gy(phi,R),Z))*xrate),
                     (int)((rmax-fy(gx(phi,R),gy(phi,R),Z))*yrate),
                  (int)((rmax+fx(gx(phi+pai/20,R),gy(phi+pai/20,R),Z))*xrate),
                  (int)((rmax-fy(gx(phi+pai/20,R),gy(phi+pai/20,R),Z))*yrate));
        }

      }
	   
      for (int i = 0; i <= 23; i++) {
        double phi = pai/12*i;

        if (i%6 == 0) {
          g.setColor(Color.pink);
        } else {
          g.setColor(Color.lightGray);	
        }
		 
        for (R =1; R <= rmax; R = R+rmax/80) {
          Z = 2*Math.sqrt(R-1);
          g.drawLine((int)((rmax+fx(gx(phi,R),gy(phi,R),Z))*xrate),
                     (int)((rmax-fy(gx(phi,R),gy(phi,R),Z))*yrate),
                (int)((rmax+fx(gx(phi,R+rmax/80),gy(phi,R+rmax/80),Z))*xrate),
                (int)((rmax-fy(gx(phi,R+rmax/80),gy(phi,R+rmax/80),Z))*yrate));
	}

      }
		   
    }
	 
    g.setColor(Color.cyan);
    R = 3; Z = 2*Math.sqrt(R-1);
    for (double phi = 0; phi <= 2*pai+pai/20; phi=phi+pai/20) {
      g.drawLine((int)((rmax+fx(gx(phi,R),gy(phi,R),Z))*xrate),
                 (int)((rmax-fy(gx(phi,R),gy(phi,R),Z))*yrate),
                 (int)((rmax+fx(gx(phi+pai/20,R),gy(phi+pai/20,R),Z))*xrate),
                 (int)((rmax-fy(gx(phi+pai/20,R),gy(phi+pai/20,R),Z))*yrate));
    }
	
    g.setColor(Color.yellow);
    g.drawOval((int)((-rmax/40+rmax+fx(x0,y0,2*Math.sqrt(r0-1)))*xrate),
               (int)((-rmax/40+rmax-fy(x0,y0,2*Math.sqrt(r0-1)))*yrate),
               (int)(rmax/20*xrate),
               (int)(rmax/20*yrate));
			   
    PRNTRKG();
	
    g.fillOval((int)((-rmax/100+rmax+fx(x,y,z))*xrate),
               (int)((-rmax/100+rmax-fy(x,y,z))*yrate),
               (int)(rmax/50*xrate),
               (int)(rmax/50*yrate));
	
	
    zrkg = xrkg;
    vrkg = xrkg;
	

    while (zrkg <= Particle.tend) { 
	
      if (Particle.dt0 <= 0) {
        dt = Math.pow(yrkg[0],1.5)/10;
      } else {
        dt = Particle.dt;
      }

      hrkg = dt/mrkg;
	
      for (int i = 1; i <= mrkg; i++) {
        
        xrkg = vrkg;
        FUNRKG();

        for (int j = 0; j < 4; j++) {
          brkg[j] = hrkg*frkg[j];
          yrkg[j] = yrkg[j]+0.5*brkg[j];
	  crkg[j] = brkg[j];
	}

	xrkg = vrkg+0.5*hrkg;
	FUNRKG();

        for (int j = 0; j < 4; j++) {
          brkg[j] = hrkg*frkg[j];
          yrkg[j] = yrkg[j]+s1rkg*(brkg[j]-crkg[j]);
          crkg[j] = s2rkg*crkg[j]+s3rkg*brkg[j];
        }

        xrkg = vrkg+0.5*hrkg;
        FUNRKG();

        for (int j = 0; j < 4; j++) {
          brkg[j] = hrkg*frkg[j];
          yrkg[j] = yrkg[j]+s4rkg*(brkg[j]-crkg[j]);
          crkg[j] = s5rkg*crkg[j]+s6rkg*brkg[j];
        }

        xrkg = vrkg+hrkg;
        FUNRKG();

        for (int j = 0; j < 4; j++) {
          brkg[j] =hrkg*frkg[j];
          yrkg[j] = yrkg[j]+brkg[j]/6-crkg[j]/3;
        }

        vrkg = vrkg+hrkg;
	  
      }
	
      zrkg = zrkg+dt;
      vrkg = zrkg;

      if (yrkg[0] <= 0) break;
	  
      PRNTRKG();
	  
      mrkg = mrkg+1;
	  
      g.fillOval((int)((-rmax/100+rmax+fx(x,y,z))*xrate),
                 (int)((-rmax/100+rmax-fy(x,y,z))*yrate),
                 (int)(rmax/50*xrate),
                 (int)(rmax/50*yrate));
			   
    }   
			 
  }
  
  public void PRNTRKG() { 

    r   = yrkg[0];
    s   = yrkg[1];
    x   = r*Math.cos(s);
    y   = r*Math.sin(s);

    if (r >1) {
      z = 2*Math.sqrt(r-1);
    } else {
      z = 0;
    }
	
  }

  
  public void FUNRKG() {

    r       = yrkg[0];
    vs      = yrkg[3]/r;
    frkg[0] = yrkg[2];
    frkg[1] = vs/r;
    frkg[2] = -0.5/(r*r)+(1-1.5/r)*vs*vs/r;
    frkg[3] = 0;
	
    if ( Particle.nr == 1) {
      frkg[2] = -0.5/(r*r)+vs*vs/r;
    }
  
  }


}
  
class Title_Canvas extends Canvas {

  public void paint(Graphics g) {

    g.setFont(new Font("TimesRoman",Font.PLAIN,15));
    g.drawString("Particle Orbit around Schwarzshild Black Hole",120,20);

  }

}


class Variable_Canvas extends Canvas {

  public void paint(Graphics g) {
	
    g.setColor(Color.red);
    g.fillOval(15,10,10,10);
	
    g.setColor(Color.cyan);
    g.drawLine(15,30,25,30);
    g.drawLine(15,31,25,31);
	
    g.setColor(Color.black);
    g.setFont(new Font("Courier",Font.PLAIN,12));    
    g.drawString("Black Hole",35,18);
    g.drawString("Last Stable Orbit",35,35);
	
    g.setFont(new Font("Courier",Font.PLAIN,10));
    g.drawString("Re,Se: position of view point",15,110);
    g.drawString(" [spherical coordinates (R, Sita, Fai)]",15,120);
    g.drawString("Alpha: extent of veiwing field",15,150);
    g.drawString("R0,F0: initial position of particle",15,180);
    g.drawString(" [polar coordinates (R, Fai)]",15,190);
    g.drawString("Vr0,Vs0: initial velocity of particle",15,220);
    g.drawString("dt: time step",15,250);
    g.drawString("END: end of calculation",15,280);
	
  }
  
}