[GRASS5] Changes between 5.0.0 release and current release branch

[Radim Blazek]

On Thursday 28 November 2002 03:29 am, Eric G. Miller wrote:
> *  Fixes interior boundary winding (shapefiles have exteriors clockwise,
>    interiors counterclockwise) for areas with holes.  AFAIK,
>    Vect_get_area_points and Vect_get_isle_points always return clockwise
>    polygons. So isle point orders are reversed. Isles will come up
>    twice, once as interior and once as exterior. (If my understanding of
>    these API's is incorrect, someone please let me know.)

I thought that direction for areas/isles is the same in grass as in shapefile
and Vect_get_isle_points returns counterclockwise vertices:

struct P_isle {
  plus_t  *lines;  /* Boundary Lines (Negative means N2 to N1
                      counter-clockwise) */
}

int Vect_get_isle_points () {
      if (Isle->lines[i] < 0) {
          start = Points.n_points - 1; inc = -1 ; end = 1;
      } else {
          end = Points.n_points - 2; inc = 1 ; start = 0;
      }
}

It is strange if shapefiles with reverted order of isles are correct.
Did you check it in ArcExplorer or other ESRI SW (AE runs on Linux)?

Radim