/*
 * fhmr.java - revised 8 Apr 05 - width 451, height 271
 * latest revision plots trajectories with and without air resistance and
 *   cleans up choice between finding range and showing motion
 * on replot, the motion is shown in real time
 * @author jackord@kw.igs.net
 */

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

public class fhmr extends Applet 
                  implements ActionListener {
  int phi; int kk=0; int rr=0; int show=0;             // Declarations
  double gr, vi, k, ax, ay, t, cf, cmph; double dt=.01;
  String b1s="Range"; Button b1=new Button(b1s);
  String b2s="Motion"; Button b2=new Button(b2s);
  Image aim, bim;
  Graphics agr, bgr;

  public void init() {
    setLayout(new FlowLayout(FlowLayout.LEFT));
    add(b1); add(b2);
    b1.addActionListener(this); b2.addActionListener(this);
    setBackground(new Color(211, 211, 211));           // Light Gray Background
  }

  double hit(Graphics g) {                             // Feynman Algorithm
    int x1, y1, x2, y2, xx1, yy1, xx2, yy2, r; long tt=0;
    double x, y, q, vx, vy, dvx, dvy, xx, yy, vxx, vyy;
    x=0; y=0; q=phi*Math.PI/18000; x1=0; y1=270; xx1=x1; yy1=225; r=5;
    vx=vi*Math.cos(q); vy=vi*Math.sin(q); t=0; vxx=vx; vyy=vy; 
    acc(vx, vy); dvx=ax*dt; dvy=ay*dt; vx=vx+dvx/2; vy=vy+dvy/2;
    if (kk==2) {                                       
      tt=System.currentTimeMillis();
    }
    do {
      t=t+dt; x=x+vx*dt; y=y+vy*dt;
      x2=(int)(cf*x); y2=(int)(270-cf*y);
      if (show==1) {                                   // Find initial v
        g.drawLine(x1, y1, x2, y2); x1=x2; y1=y2;
      }
      if (kk==2) {                                     // Plot trajectories
        bgr.drawLine(x1, y1-45, x2, y2-45); x1=x2; y1=y2;
        xx=vxx*t; yy=vyy*t-gr*t*t/2;                   // Without air
        xx2=(int)(cf*xx); yy2=(int)(225-cf*yy);
        if (xx2<=450) {
          bgr.drawLine(xx1, yy1,xx2, yy2); xx1=xx2; yy1=yy2;
        }
        agr.drawImage(bim, 0, 0, null);
        agr.fillArc(x2-r, y2-r-45, 2*r, 2*r, 0, 360);
        if (xx2<=450) {
          agr.fillArc(xx2-r, yy2-r, 2*r, 2*r, 0, 360);
        }
        g.drawImage(aim, 0, 45, null);
      }
      acc(vx+dvx/2, vy+dvy/2); dvx=ax*dt; dvy=ay*dt; vx=vx+dvx; vy=vy+dvy;
    } while (y>0);
    if (kk==2) {                                       // Set dt for real time
      dt=dt*(System.currentTimeMillis()-tt)/5500;
    }
    return x-vx*y/vy;
  }

  double ang(Graphics g) {                             // Find optimum angle
    double x, xo; long tt; int dph;
    tt=System.currentTimeMillis();
    dph=256; show=0; x=hit(g);
    do {
      phi=phi+dph; xo=x; x=hit(g);
      if (x<xo) { dph=-dph/2; }
    } while (Math.abs(dph)>2);
    do {
    } while ((System.currentTimeMillis()-tt)<1500);
    phi=phi+2*dph; show=1; x=hit(g); show=0;
    g.clearRect(50, 5, 400, 20);
    g.drawString("Vinit "+((int)(10*vi*cmph+.5))/10.+" mph at "
    +phi/100.+" deg     Range "+((int)(10*cf*x+.5))/10.+" ft", 135, 20);
    return x;
  }

  public void acc(double ux, double uy) {              // Newton's Law
    double u;
    u = Math.sqrt(ux*ux+uy*uy);
    ax=-k*u*ux; ay=-k*u*uy-gr;
  }

  public void paint(Graphics g) {                      // Paint
    double m, r, va, vb, vim, dvi, range, range2, rx;
    aim=createImage(451, 226);                         // Animation buffers
    agr=aim.getGraphics();
    bim=createImage(451, 226);                     
    bgr=bim.getGraphics();
    agr.setColor(Color.red);
    bgr.setColor(Color.black);
    for (int i=0; i<=10; i=i+1) {
      bgr.drawLine(45*i, 0, 45*i, 225);
    }
    for (int i=0; i<=5; i=i+1) {
      bgr.drawLine(0, 45*i, 450, 45*i);
    }
    g.drawImage(bim, 0, 45, null);
    g.setColor(Color.blue); bgr.setColor(Color.blue);
    cf=100/2.54/12; cmph=3600/.0254/12/5280; rx=0;
    if (kk==1) {
      m=5.125/16/2.2; r=9.125*.0254/2/Math.PI;
      gr=9.8; k=.87*r*r/m; range=450/cf;
      dvi=Math.sqrt(gr*range); vi=0; phi=3000;
      do {                                             // Bracket the Range
        vi=vi+dvi;
      } while (ang(g)<range);
      va=vi-dvi; vb=vi;
      do {                                             // Bisection Algorithm
        vi=(va+vb)/2;
        if (ang(g)>range) {
          vb=vi;
        }
        else {
          va=vi;
        }
      } while (vb-va>.02);
      vi=(va+vb)/2; g.setColor(Color.red); show=1;
      rx=hit(g); rr=1;
    }
    if (kk==2) {                                       // Plot trajectories
      rx=hit(g);
    }
    vim=vi*cmph; rx=((int)(10*cf*rx+.5))/10.;
    range2=vi*vi*Math.sin(2*phi*Math.PI/18000)/gr*cf;
    if (kk==2) {
      g.drawString("Flight time "+((int)(100*t+.5))/100.+
      " sec     Range "+(int)range2+" ft without air", 135, 35);
    }
    if (kk>0) {
      g.clearRect(50, 5, 400, 20);
      g.drawString("Vinit "+((int)(10*vim+.5))/10.+" mph at "
      +phi/100.+" deg     Range "+rx+" ft", 135, 20);
      kk=0;
    }
  }

  public void actionPerformed(ActionEvent e) {         // Buttons
    String tst;
    tst=e.getActionCommand();
    if (b1s.equals(tst)) {                             // Find the Range
      kk=1; repaint();
    }
    if ((b2s.equals(tst))&&(rr==1)) {                  // Plot the Motion
      kk=2; repaint();
    }
  }
}