/* -*-ePiX-*- */
#include "epix.h"
#include "tolman.h"
using namespace ePiX;

double wd(0.6), Lft(3), Rght(6.5);

double tmin(10), tmax(180 - tmin), dt(5);
P ctr(2.75,1), v1(0, 0.3), v2(-0.25,0);

void axes(const P& loc)
{
  line(loc, loc + P(1,0));
  line(loc, loc + P(0,1));
  line(loc, loc + cis(-135));

  label(loc + P(1,0), P(0,-2), "$Y$", bl);
  label(loc + P(0,1), P(2,-2), "$Z$", r);
  label(loc + cis(-135), P(4,0), "$X$", r);
}

P my_loc(double t)
{
  return ctr + Cos(t)*v1 + Sin(t)*v2;
}

void my_Arrow(){

  ellipse(ctr, v1, v2, tmin, tmax);
  arrow(my_loc(tmax - 5*dt), my_loc(tmax));

  double pip(pt_to_screen(1.5));
  plain();

  for (int i=0; i<5; ++i)
    {
      double t(tmin + 1.5*i*dt);
      P tail(my_loc(t)), head(my_loc(t + dt));
      P dL(head - tail);
      dL *= pip/norm(dL);

      line(tail, tail - sc_arr*dL + 1.5*J(dL));
      line(tail, tail - sc_arr*dL - 1.5*J(dL));
    }
}

int main()
{
  picture(P(0,0), P(7,2), "4.2 x 1.2in");

  begin();
  degrees();
  arrow_init();

  bold();
  axes(P(1, 1));

  line(P(2.5,1), P(xmax(),1));

  my_Arrow();

  fill(Black(0.2));
  rect(P(Lft, 2 - wd), P(Rght, 2));
  rect(P(Lft, 0), P(Rght, wd));
  nofill();

  dashed();
  dash_size(6);

  line(P(Lft,0), P(Lft,2));
  line(P(Rght,0), P(Rght,2));

  label(P(Rght, 2 - 0.5*wd), P(2,0), "$A$", r);
  label(P(Lft, 2 - 0.5*wd), P(-2,0), "$A$", l);

  font_face("sc");
  label(P(0.5*(xmin() + xmax()),ymin()), P(0,-12), "Fig.~15.", b);
  tikz_format();
  end();
}