Provided by: libncarg-dev_6.3.0-6build1_amd64 bug


       gfill_area  - output primitive for filling polygonal areas.


       #include <ncarg/gks.h>

       void gfill_area(const Gpoint_list *point_list);


                   (Gint,  Input)  -  The  number of points in the polygon to be filled.  Must be
                   greater than two.

                   (Gpoint *, Input) - The X and Y world coordinates of the polygon.


       The area to be filled is delimited by the sequence of straight  line  segments  connecting
       the      successive      points     ((point_list.points[0].x,     point_list.points[0].y),
       point_list.points[point_list.num_points-1].y))  The last point in the polygon is connected
       to the first point with a straight line segment in the case that it is not the same as the
       first point.

       Given  a polygon whose edges cross each other, it becomes ambiguous as to what constitutes
       the "inside" of the polygon.  The algorithm used in GKS is as follows: for a given  point,
       draw a ray starting at that point and going to infinity in any direction; if the number of
       intersections between the ray and the polygon is odd, the point  is  within  the  polygon,
       otherwise  it  is  outside.   If  the  straight  line  passes  through  a  polygon  vertex
       tangentially, the intersection count is not affected.  If a point is within  the  polygon,
       it is included in the area to be filled.

       Several  interior styles (hollow, solid, and various hatch patterns) can be selected.  See
       the man pages for gset_fill_int_style and gset_fill_style_ind for these.

       Note well: By default in GKS, the interior fill style is hollow, or no fill. If  you  call
       gfill_area  and  do  not  get a filled interior as you expected, you will probably need to
       call gset_fill_int_style to set the fill style to something other than "hollow".


       To use the GKS C-binding routines, load the ncarg_gks and ncarg_c libraries.


       Online: gset_fill_int_style(3NCARG),  gset_fill_style_ind(3NCARG),  gset_colr_rep(3NCARG),
       gset_fill_colr_ind(3NCARG),    ginq_fill_int_style(3NCARG),   ginq_fill_style_ind(3NCARG),
       gks(3NCARG), ncarg_gks_cbind(3NCARG)

       Hardcopy: User's Guide for NCAR GKS-0A Graphics; NCAR Graphics Fundamentals, UNIX Version


       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.