/* -*-ePiX-*- */
#include "epix.h"
using namespace ePiX;
void displ(const P& tail, const P& dir,
	   const std::string& msgt = "", const std::string& msgh = "")
{
  P mid(tail + 0.5*dir);
  arrow(tail, mid);
  line(mid, tail + dir);

  if (msgt != "")
    label(tail, -2*dir, msgt, l);

  if (msgh != "")
    label(tail + dir,  2*dir, msgh, r);
}

int main()
{
  picture(P(0, -1), P(5, 3), "4 x 3.2in");

  begin();
  arrow_inset(0.5);
  arrow_ratio(2);
  arrow_width(2);

  P dir1(1.75, 1), dir2(-0.75*J(dir1)), dX(1,0),
    pO(0,0), pA(dir1), pB(dir2), pC(dir1 + dir2),
    pP(1.5,2.25), pQ(pP + dir1), pQ1(pP + dir1 + dir2), pQ2(pP + dir2),
    pPp(pQ + dX), pQp(pQ1 + dX);

  bold();

  line(pO, P(4, 0));
  line(pO, P(0, 3));

  displ(pP, dir1, "$P$", "$Q$");
  displ(pO, dir1, "$O$", "$A$");

  displ(pQ, dir2);
  displ(pO, dir2);

  displ(pPp, dir2);

  dashed();
  dash_size(6);
  line(pA, pC);
  line(pB, pC);

  line(pP, pQ2);
  line(pQ2, pQ1);

  label(pB, P(-2,-2), "$B$", bl);
  label(pC, P( 2,-2), "$C$", br);

  label(pQ1, P(2,-2), "$Q_{1}$", br);
  label(pQ2, P(4, 8), "$Q_{2}$", t);

  label(pPp, P(2, 2), "$P'$", tr);
  label(pQp, P(2, 2), "$Q'$", tr);

  tikz_format();
  end();
}