ptarray_locate_along()

static POINTARRAY* ptarray_locate_along ( const POINTARRAY *  pa, double  m, double  offset  )

static

Definition at line 79 of file lwlinearreferencing.c.

References getPoint4d_p(), LW_FALSE, POINTARRAY::npoints, ptarray_append_point(), ptarray_construct_empty(), ptarray_has_m(), ptarray_has_z(), and segment_locate_along().

Referenced by lwline_locate_along().

{
        int i;
        POINT4D p1, p2, pn;
        POINTARRAY *dpa = NULL;

        /* Can't do anything with degenerate point arrays */
        if ( ! pa || pa->npoints < 2 ) return NULL;

        /* Walk through each segment in the point array */
        for ( i = 1; i < pa->npoints; i++ )
        {
                getPoint4d_p(pa, i-1, &p1);
                getPoint4d_p(pa, i, &p2);

                /* No derived point? Move to next segment. */
                if ( segment_locate_along(&p1, &p2, m, offset, &pn) == LW_FALSE )
                        continue;

                /* No pointarray, make a fresh one */
                if ( dpa == NULL )
                        dpa = ptarray_construct_empty(ptarray_has_z(pa), ptarray_has_m(pa), 8);

                /* Add our new point to the array */
                ptarray_append_point(dpa, &pn, 0);
        }

        return dpa;
}

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