#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Box.H>
#include <FL/fl_draw.H>

#define COMPLEX 1	// must be 0 or 1
#define USE_FL_GAP 1	// must be 0 or 1 (irrelevant if COMPLEX == 0)
			// 0 => okay, 1 => bad

#if (COMPLEX)
  
#define BEGIN_POLYGON	fl_begin_complex_polygon();
#define END_POLYGON	fl_end_complex_polygon();

#if (USE_FL_GAP)
#define GAP		fl_gap(); // don't use fl_gap() !
#else
#define GAP		END_POLYGON fl_color(FL_BLACK); BEGIN_POLYGON // this is correct
#endif

#else // COMPLEX

#define BEGIN_POLYGON	fl_begin_polygon();
#define END_POLYGON	fl_end_polygon();
#define GAP		END_POLYGON BEGIN_POLYGON

#endif

class MyBox : public Fl_Box {

public:

  MyBox(int X, int Y, int W, int H) : Fl_Box(X,Y,W,H) {};

  void draw() {

    Fl_Box::draw();

    fl_color(FL_BLUE);

    fl_push_matrix();
    fl_translate(100,0);

    BEGIN_POLYGON

      fl_vertex(40, 140);
      fl_vertex(20, 100);
      fl_vertex( 0, 140);
      fl_vertex(20, 180);
      fl_vertex(40, 140);

    GAP

      fl_color(FL_GREEN);

      fl_vertex(60, 140);
      fl_vertex(80, 100);
      fl_vertex(100, 140);
      fl_vertex(80,  180);
      fl_vertex(60,  140);

    GAP

      fl_color(FL_RED);

      fl_vertex(70,  240);
      fl_vertex(90,  280);
      fl_vertex(110, 240);
      fl_vertex(90,  200);
      fl_vertex(70,  240);

    END_POLYGON

    fl_pop_matrix();

    fl_color(FL_BLACK);
  }

};

int main(int argc, char **argv) {
  Fl_Window *window = new Fl_Window(640,440);
  MyBox *box = new MyBox(20,20,600,400);
  box->box(FL_UP_BOX);
  box->color(FL_YELLOW);

  window->end();
  window->show(argc, argv);
  return Fl::run();
}