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/*!
\file lib/vector/vedit/snap.c
\brief Vedit library - snapping
(C) 2007-2008 by the GRASS Development Team
This program is free software under the GNU General Public License
(>=v2). Read the file COPYING that comes with GRASS for details.
\author Martin Landa <landa.martin gmail.com>
*/
#include <grass/vedit.h>
/*!
\brief Snap given point to the nearest primitive
\param Map pointer to Map_info
\param line line to be excluded (point on line)
\param x,y,z point on line to be snapped
\param thresh snapping threshold (>0)
\param vertex snap also to vertex (non-zero)
\return 1 snapped
\return 0 not snapped
*/
int Vedit_snap_point(struct Map_info *Map, int line, double *x, double *y,
double *z, double thresh, int vertex)
{
struct line_pnts *Points;
int i, snapped;
int line2snap, mindist_idx;
double dist, mindist;
snapped = 0;
mindist_idx = -1;
mindist = thresh;
Points = Vect_new_line_struct();
line2snap = Vect_find_line(Map, *x, *y, *z, -1, thresh, WITHOUT_Z, line);
if (line2snap > 0) {
Vect_read_line(Map, Points, NULL, line2snap);
if (!Vect_line_alive(Map, line2snap)) {
Vect_destroy_line_struct(Points);
return snapped;
}
for (i = 0; i < Points->n_points; i++) {
if (i > 0 && i < Points->n_points - 1)
if (!vertex)
continue;
dist = Vect_points_distance(*x, *y, *z, Points->x[i], Points->y[i],
Points->z[i], WITHOUT_Z);
if (mindist >= dist) {
mindist = dist;
mindist_idx = i;
}
}
if (mindist_idx > -1) {
*x = Points->x[mindist_idx];
*y = Points->y[mindist_idx];
*z = Points->z[mindist_idx];
snapped = 1;
}
}
G_debug(3, "Vedit_snap_point(): map=%s, line2snap=%d, snapped=%d",
Map->name, line2snap, snapped);
Vect_destroy_line_struct(Points);
return snapped;
}
/*!
\brief Snap selected primitive to its nearest primitive
\param Map pointer to Map_info
\param BgMap,nbgmaps list of background maps used for snapping
\param line line id to be snapped (if already written, otherwise -1)
\param Points line geometry
\param layer layer number
\param thresh threshold value used for snapping (>0)
\param to_vertex allow snapping also to vertex
\return 1 line snapped
\return 0 line not snapped
\return -1 line is dead (if 'line' is > 0)
*/
int Vedit_snap_line(struct Map_info *Map, struct Map_info **BgMap, int nbgmaps,
int line, struct line_pnts *Points, double thresh,
int to_vertex)
{
int i, npoints, node, rewrite;
double *x, *y, *z;
struct line_cats *Cats;
Cats = Vect_new_cats_struct();
G_debug(3, "Vedit_snap_line(): thresh=%g, to_vertex=%d", thresh, to_vertex);
if (line > 0 && !Vect_line_alive(Map, line))
return -1;
npoints = Points->n_points;
x = Points->x;
y = Points->y;
z = Points->z;
rewrite = 0;
for (node = 0; node < npoints; node++) {
if ((node > 0 && node < npoints - 1) && !to_vertex)
continue;
if (Vedit_snap_point(Map, line, &x[node], &y[node], &z[node], thresh,
to_vertex)) {
rewrite = 1;
}
else {
/* check also background maps */
for (i = 0; i < nbgmaps; i++) {
if (Vedit_snap_point(BgMap[i], -1, &x[node], &y[node], &z[node],
thresh, to_vertex)) {
rewrite = 1;
break; /* snapped, don't continue */
}
}
}
} /* for each line vertex */
/* close boundaries or lines */
if (!rewrite &&
Vect_points_distance(x[0], y[0], z[0], x[npoints - 1], y[npoints - 1],
z[npoints - 1], WITHOUT_Z) <= thresh) {
x[npoints - 1] = x[0];
y[npoints - 1] = y[0];
z[npoints - 1] = z[0];
rewrite = 1;
}
G_debug(3, "Vedit_snap_line(): line=%d, snapped=%d", line, rewrite);
Vect_destroy_cats_struct(Cats);
return rewrite;
}
/*!
\brief Snap lines/boundaries
\param Map pointer to Map_info
\param BgMap,nbgmaps list of background maps used for snapping
\param List list of lines to be snapped
\param layer layer number
\param thresh threshold value used for snapping (>0)
\param to_vertex allow snapping also to vertex
\return number of snapped lines
\return -1 on error
*/
int Vedit_snap_lines(struct Map_info *Map, struct Map_info **BgMap, int nbgmaps,
struct ilist *List, double thresh, int to_vertex)
{
int i, line, type;
int nlines_modified = 0;
struct line_pnts *Points;
struct line_cats *Cats;
Points = Vect_new_line_struct();
Cats = Vect_new_cats_struct();
for (i = 0; i < List->n_values; i++) {
line = List->value[i];
type = Vect_read_line(Map, Points, Cats, line);
if (!(type & (GV_POINT | GV_LINES))) {
continue;
}
if (Vedit_snap_line(Map, BgMap, nbgmaps, line, Points, thresh,
to_vertex) == 1) {
if (Vect_rewrite_line(Map, line, type, Points, Cats) < 0) {
return -1;
}
nlines_modified++;
}
}
Vect_destroy_line_struct(Points);
Vect_destroy_cats_struct(Cats);
return nlines_modified;
}
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