vector/diglib/box.c

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/*****************************************************************************
 *
 * MODULE:       Vector library
 *
 * AUTHOR(S):    Radim Blazek
 *
 * PURPOSE:      Lower level functions for reading/writing/manipulating vectors.
 *
 * COPYRIGHT:    (C) 2001 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.
 *
 *****************************************************************************/
 
#include <stdlib.h>
#include <grass/vector.h>
 
/*
 *  dig_line_box ()
 *  set box to points extent
 */
int dig_line_box(const struct line_pnts *Points, struct bound_box *Box)
{
    int i;
 
    if (Points->n_points <= 0) {
        G_zero(Box, sizeof(struct bound_box));
        return 0;
    }
 
    Box->E = Points->x[0];
    Box->W = Points->x[0];
    Box->N = Points->y[0];
    Box->S = Points->y[0];
    Box->T = Points->z[0];
    Box->B = Points->z[0];
 
    for (i = 1; i < Points->n_points; i++) {
        if (Points->x[i] > Box->E)
            Box->E = Points->x[i];
        else if (Points->x[i] < Box->W)
            Box->W = Points->x[i];
 
        if (Points->y[i] > Box->N)
            Box->N = Points->y[i];
        else if (Points->y[i] < Box->S)
            Box->S = Points->y[i];
 
        if (Points->z[i] > Box->T)
            Box->T = Points->z[i];
        else if (Points->z[i] < Box->B)
            Box->B = Points->z[i];
    }
 
    return 1;
}
 
/*
 *  dig_box_copy ()
 *  Copy B to A.
 */
int dig_box_copy(struct bound_box *A, struct bound_box *B)
{
 
    A->N = B->N;
    A->S = B->S;
    A->E = B->E;
    A->W = B->W;
    A->T = B->T;
    A->B = B->B;
 
    return 1;
}
 
/*
 * dig_box_extend ()
 * Extend A by B.
 */
int dig_box_extend(struct bound_box *A, struct bound_box *B)
{
 
    if (B->N > A->N)
        A->N = B->N;
    if (B->S < A->S)
        A->S = B->S;
    if (B->E > A->E)
        A->E = B->E;
    if (B->W < A->W)
        A->W = B->W;
    if (B->T > A->T)
        A->T = B->T;
    if (B->B < A->B)
        A->B = B->B;
 
    return 1;
}