overlay.c

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/*!
   \file lib/vector/Vlib/overlay.c
 
   \brief Vector library - overlays
 
   Higher level functions for reading/writing/manipulating vectors.
 
   This is file is just example and starting point for writing overlay
   functions!!!
 
   SPDX-FileCopyrightText: 2001-2009 GRASS Development Team
   SPDX-License-Identifier: GPL-2.0-or-later
 
   \author Radim Blazek
 */
 
#include <string.h>
#include <grass/vector.h>
#include <grass/glocale.h>
 
int Vect_overlay_and(struct Map_info *, int, struct ilist *, struct ilist *,
                     struct Map_info *, int, struct ilist *, struct ilist *,
                     struct Map_info *);
 
/*!
   \brief Get operator code from string
 
   \param str operator code string
 
   \return operator code
   \return -1 on error
 */
int Vect_overlay_str_to_operator(const char *str)
{
 
    if (strcmp(str, GV_ON_AND) == 0)
        return GV_O_AND;
    else if (strcmp(str, GV_ON_OVERLAP) == 0)
        return GV_O_OVERLAP;
 
    return -1;
}
 
/*!
   \brief Overlay 2 vector maps and create new one
 
   \param AMap vector map A
   \param atype feature type for A
   \param AList unused ?
   \param AAList unused ?
   \param BMap vector map B
   \param btype feature type for B
   \param BList unused ?
   \param BAList unused ?
   \param operator operator code
   \param[out] OMap output vector map
 
   \return 0 on success
 */
int Vect_overlay(struct Map_info *AMap, int atype, struct ilist *AList,
                 struct ilist *AAList, /* map A */
                 struct Map_info *BMap, int btype, struct ilist *BList,
                 struct ilist *BAList, /* map B */
                 int operator, struct Map_info *OMap)
{ /* output map */
    switch (operator) {
    case GV_O_AND:
        Vect_overlay_and(AMap, atype, AList, AAList, BMap, btype, BList, BAList,
                         OMap);
        break;
    default:
        G_fatal_error("Vect_overlay(): %s", _("unknown operator"));
    }
 
    return 0;
}
 
/*!
   \brief Overlay 2 vector maps with AND.
 
   AND supports:point line area
   point  +     -    +
   line   -     -    -
   area   +     -    -
 
   \param AMap vector map A
   \param atype feature type for A
   \param AList unused ?
   \param AAList unused ?
   \param BMap vector map B
   \param btype feature type for B
   \param BList unused ?
   \param BAList unused ?
   \param OMap output vector map
 
   \return 1 on success
   \return 0 on error
 */
int Vect_overlay_and(struct Map_info *AMap, int atype,
                     struct ilist *AList G_UNUSED,
                     struct ilist *AAList G_UNUSED, struct Map_info *BMap,
                     int btype, struct ilist *BList G_UNUSED,
                     struct ilist *BAList G_UNUSED, struct Map_info *OMap)
{
    int i, j, k, line, altype, bltype, oltype, area, centr;
    struct line_pnts *Points;
    struct line_cats *ACats, *BCats, *OCats;
    struct ilist *AOList, *BOList;
    struct boxlist *boxlist;
    struct bound_box box;
 
    /* TODO: support Lists */
 
    Points = Vect_new_line_struct();
    ACats = Vect_new_cats_struct();
    BCats = Vect_new_cats_struct();
    OCats = Vect_new_cats_struct();
    AOList = Vect_new_list();
    BOList = Vect_new_list();
    boxlist = Vect_new_boxlist(0);
 
    /* TODO: support all types; at present only point x point, area x point and
     * point x area supported  */
    if ((atype & GV_LINES) || (btype & GV_LINES))
        G_warning(
            _("Overlay: line/boundary types not supported by AND operator"));
 
    if ((atype & GV_AREA) && (btype & GV_AREA))
        G_warning(
            _("Overlay: area x area types not supported by AND operator"));
 
    /* TODO: more points in one node in one map */
 
    /* point x point: select all points with identical coordinates in both maps
     */
    if ((atype & GV_POINTS) &&
        (btype & GV_POINTS)) { /* both points and centroids */
        G_debug(3, "overlay: AND: point x point");
        for (i = 1; i <= Vect_get_num_lines(AMap); i++) {
            altype = Vect_read_line(AMap, Points, ACats, i);
            if (!(altype & GV_POINTS))
                continue;
 
            box.E = box.W = Points->x[0];
            box.N = box.S = Points->y[0];
            box.T = box.B = Points->z[0];
            Vect_select_lines_by_box(BMap, &box, GV_POINTS, boxlist);
 
            Vect_reset_cats(OCats);
 
            for (j = 0; j < boxlist->n_values; j++) {
                line = boxlist->id[j];
                bltype = Vect_read_line(BMap, NULL, BCats, line);
                if (!(bltype & GV_POINTS))
                    continue;
 
                /* Identical points found -> write out */
                /* TODO: do something if fields in ACats and BCats are identical
                 */
                for (k = 0; k < ACats->n_cats; k++)
                    Vect_cat_set(OCats, ACats->field[k], ACats->cat[k]);
 
                for (k = 0; k < BCats->n_cats; k++)
                    Vect_cat_set(OCats, BCats->field[k], BCats->cat[k]);
 
                /* TODO: what to do if one type is GV_POINT and second
                 * GV_CENTROID */
                oltype = altype;
                Vect_write_line(OMap, oltype, Points, OCats);
                Vect_list_append(AOList, i); /* add to list of written lines */
                Vect_list_append(BOList, line);
                break;
            }
        }
    }
 
    /* TODO: check only labeled areas */
    /* point x area: select points from A in areas in B */
    if ((atype & GV_POINTS) &&
        (btype & GV_AREA)) { /* both points and centroids */
        G_debug(3, "overlay: AND: point x area");
 
        for (i = 1; i <= Vect_get_num_lines(AMap); i++) {
            altype = Vect_read_line(AMap, Points, ACats, i);
            if (!(altype & GV_POINTS))
                continue;
 
            area = Vect_find_area(BMap, Points->x[0], Points->y[0]);
            if (area == 0)
                continue;
 
            Vect_reset_cats(OCats);
 
            /* TODO: do something if fields in ACats and BCats are identical */
            for (k = 0; k < ACats->n_cats; k++)
                Vect_cat_set(OCats, ACats->field[k], ACats->cat[k]);
 
            centr = Vect_get_area_centroid(BMap, area);
            if (centr > 0) {
                bltype = Vect_read_line(BMap, NULL, BCats, centr);
                for (k = 0; k < BCats->n_cats; k++)
                    Vect_cat_set(OCats, BCats->field[k], BCats->cat[k]);
            }
 
            /* Check if not yet written */
            if (!(Vect_val_in_list(AOList, i))) {
                Vect_write_line(OMap, altype, Points, OCats);
                Vect_list_append(AOList, i);
            }
        }
    }
    /* area x point: select points from B in areas in A */
    if ((btype & GV_POINTS) &&
        (atype & GV_AREA)) { /* both points and centroids */
        G_debug(3, "overlay: AND: area x point");
 
        for (i = 1; i <= Vect_get_num_lines(BMap); i++) {
            bltype = Vect_read_line(BMap, Points, BCats, i);
            if (!(bltype & GV_POINTS))
                continue;
 
            area = Vect_find_area(AMap, Points->x[0], Points->y[0]);
            if (area == 0)
                continue;
 
            Vect_reset_cats(OCats);
 
            /* TODO: do something if fields in ACats and BCats are identical */
            for (k = 0; k < BCats->n_cats; k++)
                Vect_cat_set(OCats, BCats->field[k], BCats->cat[k]);
 
            centr = Vect_get_area_centroid(AMap, area);
            if (centr > 0) {
                altype = Vect_read_line(AMap, NULL, ACats, centr);
                for (k = 0; k < ACats->n_cats; k++)
                    Vect_cat_set(OCats, ACats->field[k], ACats->cat[k]);
            }
 
            /* Check if not yet written */
            if (!(Vect_val_in_list(BOList, i))) {
                Vect_write_line(OMap, bltype, Points, OCats);
                Vect_list_append(BOList, i);
            }
        }
    }
 
    Vect_destroy_line_struct(Points);
    Vect_destroy_cats_struct(ACats);
    Vect_destroy_cats_struct(BCats);
    Vect_destroy_cats_struct(OCats);
    Vect_destroy_list(AOList);
    Vect_destroy_list(BOList);
    Vect_destroy_boxlist(boxlist);
 
    return 0;
}