/*!
\brief Returns polygon array of points (outer ring) of given area
\param Map pointer to Map_info structure
\param area area id
\param[out] BPoints points array
\return number of points
\return -1 on error
*/
int Vect_get_area_points(const struct Map_info *Map,
int area, struct line_pnts *BPoints)
{
const struct Plus_head *Plus;
struct P_area *Area;
G_debug(3, "Vect_get_area_points(): area = %d", area);
Vect_reset_line(BPoints);
Plus = &(Map->plus);
Area = Plus->Area[area];
if (Area == NULL) { /* dead area */
G_warning(_("Attempt to read points of nonexistent area"));
return -1; /* error, because we should not read dead areas */
}
G_debug(3, " n_lines = %d", Area->n_lines);
return Vect__get_area_points(Map, Area->lines, Area->n_lines, BPoints);
}
/*!
\brief Build area on given side of line (GV_LEFT or GV_RIGHT)
\param Map pointer to Map_info structure
\param iline line id
\param side side (GV_LEFT or GV_RIGHT)
\return > 0 area id
\return < 0 isle id
\return 0 not created (may also already exist)
*/
int Vect_build_line_area(struct Map_info *Map, int iline, int side)
{
int area, isle, n_lines;
struct Plus_head *plus;
struct bound_box box;
static struct line_pnts *APoints = NULL;
plus_t *lines;
double area_size;
plus = &(Map->plus);
G_debug(3, "Vect_build_line_area() line = %d, side = %d", iline, side);
if (!APoints)
APoints = Vect_new_line_struct();
/* get area */
area = dig_line_get_area(plus, iline, side);
if (area != 0) {
/* -> there is already an area on this side of the line, skip */
G_debug(3, " area/isle = %d -> skip", area);
return 0;
}
/* build an area with this line */
n_lines = dig_build_area_with_line(plus, iline, side, &lines);
G_debug(3, " n_lines = %d", n_lines);
if (n_lines < 1) {
return 0;
} /* area was not built */
/* get line points which forms a boundary of an area */
Vect__get_area_points(Map, lines, n_lines, APoints);
dig_line_box(APoints, &box);
Vect_line_prune(APoints);
if (APoints->n_points < 4) {
G_warning(_("Area of size = 0.0 (less than 4 vertices) ignored"));
return 0;
}
/* Area or island ? */
dig_find_area_poly(APoints, &area_size);
/* area_size = dig_find_poly_orientation(APoints); */
/* area_size is not real area size, we are only interested in the sign */
G_debug(3, " area/isle size = %f", area_size);
if (area_size > 0) { /* CW: area */
/* add area structure to plus */
area = dig_add_area(plus, n_lines, lines, &box);
if (area == -1) { /* error */
G_fatal_error(_("Unable to add area (map closed, topo saved)"));
}
G_debug(3, " -> area %d", area);
return area;
}
else if (area_size < 0) { /* CCW: island */
isle = dig_add_isle(plus, n_lines, lines, &box);
if (isle == -1) { /* error */
G_fatal_error(_("Unable to add isle (map closed, topo saved)"));
}
G_debug(3, " -> isle %d", isle);
return -isle;
}
else {
/* TODO: What to do with such areas? Should be areas/isles of size 0 stored,
* so that may be found and cleaned by some utility
* Note: it would be useful for vertical closed polygons, but such would be added twice
* as area */
G_warning(_("Area of size = 0.0 ignored"));
}
return 0;
}
