status.i4.v = wn_polygon_c(num_vertices.i4.v, xy.r4a.r)

	This routine draws a polygon in a graphical window specified by a
	previous call to wn_active(_c).  wn_view(_c) and wn_world(_c)
	must also be called before calling this routine.  The color of the
	polygon is determined by the most recent call to wn_color(_c).
	Whether or not it is drawn as a filled polygon is determined by the
	most recent call to wn_fill_mode(_c).

	num_vertices		number of vertices
	xy			array of x-y pairs in real world coordinates 

	This function returns ACNET status values as follows:

	OK			success
	CBS_NOSETUP		an active window has not been established
	CBS_MEMFAIL		failed in allocating dynamic memory

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	wn_fill_mode(_c), wn_vector_width(_c), wn_vector_grain(_c),
	wn_color(_c), wn_user_defined_color_c, wn_read_user_defined_color,
	wn_view(_c), wn_world(_c), wn_active(_c), wn_flush,

	C/C++ usage:

	int	status;
	int	num_vertices = NUM_VERTICES;
	static const float	xy[NUM_VERTICES*2] =
	{1.0, 3.0, 9.0, 7.0, 9.0, 3.0};

	status = wn_polygon_c(num_vertices,xy);