_lwt_toposnap()

static LWGEOM* _lwt_toposnap ( LWGEOM *  src, LWGEOM *  tgt, double  tol  )

static

Definition at line 420 of file lwgeom_topo.c.

References LWDEBUGF, lwgeom_count_vertices(), lwgeom_free(), lwgeom_remove_repeated_points(), and lwgeom_snap().

Referenced by lwt_AddLine(), and lwt_AddPoint().

{
  LWGEOM *tmp = src;
  LWGEOM *tmp2;
  int changed;
  int iterations = 0;

  int maxiterations = lwgeom_count_vertices(tgt);

  /* GEOS snapping can be unstable */
  /* See https://trac.osgeo.org/geos/ticket/760 */
  do {
    LWGEOM *tmp3;
    tmp2 = lwgeom_snap(tmp, tgt, tol);
    ++iterations;
    changed = ( lwgeom_count_vertices(tmp2) != lwgeom_count_vertices(tmp) );
#if GEOS_NUMERIC_VERSION < 30309
    /* Up to GEOS-3.3.8, snapping could duplicate points */
    if ( changed ) {
      tmp3 = lwgeom_remove_repeated_points( tmp2, 0 );
      lwgeom_free(tmp2);
      tmp2 = tmp3;
      changed = ( lwgeom_count_vertices(tmp2) != lwgeom_count_vertices(tmp) );
    }
#endif /* GEOS_NUMERIC_VERSION < 30309 */
    LWDEBUGF(2, "After iteration %d, geometry changed ? %d (%d vs %d vertices)", iterations, changed, lwgeom_count_vertices(tmp2), lwgeom_count_vertices(tmp));
    if ( tmp != src ) lwgeom_free(tmp);
    tmp = tmp2;
  } while ( changed && iterations <= maxiterations );

  LWDEBUGF(1, "It took %d/%d iterations to properly snap",
              iterations, maxiterations);

  return tmp;
}

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