_lwt_FindNextRingEdge()

static int _lwt_FindNextRingEdge ( const POINTARRAY *  ring, int  from, const LWT_ISO_EDGE *  edges, int  numedges  )

static

Definition at line 2918 of file lwgeom_topo.c.

{
  int i;
  POINT2D p1;
 
  /* Get starting ring point */
  getPoint2d_p(ring, from, &p1);
 
  LWDEBUGF(1, "Ring's 'from' point (%d) is %g,%g", from, p1.x, p1.y);
 
  /* find the edges defining the next portion of ring starting from
   * vertex "from" */
  for ( i=0; i<numedges; ++i )
  {
    const LWT_ISO_EDGE *isoe = &(edges[i]);
    LWLINE *edge = isoe->geom;
    POINTARRAY *epa = edge->points;
    POINT2D p2, pt;
    int match = 0;
    uint32_t j;
 
    /* Skip if the edge is a dangling one */
    if ( isoe->face_left == isoe->face_right )
    {
      LWDEBUGF(3, "_lwt_FindNextRingEdge: edge %" LWTFMT_ELEMID
                  " has same face (%" LWTFMT_ELEMID
                  ") on both sides, skipping",
                  isoe->edge_id, isoe->face_left);
      continue;
    }
 
    if (epa->npoints < 2)
    {
      LWDEBUGF(3, "_lwt_FindNextRingEdge: edge %" LWTFMT_ELEMID
                  " has only %"PRIu32" points",
                  isoe->edge_id, epa->npoints);
      continue;
    }
 
#if 0
    size_t sz;
    LWDEBUGF(1, "Edge %" LWTFMT_ELEMID " is %s",
                isoe->edge_id,
                lwgeom_to_wkt(lwline_as_lwgeom(edge), WKT_EXTENDED, 2, &sz));
#endif
 
    /* ptarray_remove_repeated_points ? */
 
    getPoint2d_p(epa, 0, &p2);
    LWDEBUGF(1, "Edge %" LWTFMT_ELEMID " 'first' point is %g,%g",
                isoe->edge_id, p2.x, p2.y);
    LWDEBUGF(1, "Rings's 'from' point is still %g,%g", p1.x, p1.y);
    if ( p2d_same(&p1, &p2) )
    {
      LWDEBUG(1, "p2d_same(p1,p2) returned true");
      LWDEBUGF(1, "First point of edge %" LWTFMT_ELEMID
                  " matches ring vertex %d", isoe->edge_id, from);
      /* first point matches, let's check next non-equal one */
      for ( j=1; j<epa->npoints; ++j )
      {
        getPoint2d_p(epa, j, &p2);
        LWDEBUGF(1, "Edge %" LWTFMT_ELEMID " 'next' point %d is %g,%g",
                    isoe->edge_id, j, p2.x, p2.y);
        /* we won't check duplicated edge points */
        if ( p2d_same(&p1, &p2) ) continue;
        /* we assume there are no duplicated points in ring */
        getPoint2d_p(ring, from+1, &pt);
        LWDEBUGF(1, "Ring's point %d is %g,%g",
                    from+1, pt.x, pt.y);
        match = p2d_same(&pt, &p2);
        break; /* we want to check a single non-equal next vertex */
      }
#if POSTGIS_DEBUG_LEVEL > 0
      if ( match ) {
        LWDEBUGF(1, "Prev point of edge %" LWTFMT_ELEMID
                    " matches ring vertex %d", isoe->edge_id, from+1);
      } else {
        LWDEBUGF(1, "Prev point of edge %" LWTFMT_ELEMID
                    " does not match ring vertex %d", isoe->edge_id, from+1);
      }
#endif
    }
 
    if ( ! match )
    {
      LWDEBUGF(1, "Edge %" LWTFMT_ELEMID " did not match as forward",
                 isoe->edge_id);
      getPoint2d_p(epa, epa->npoints-1, &p2);
      LWDEBUGF(1, "Edge %" LWTFMT_ELEMID " 'last' point is %g,%g",
                  isoe->edge_id, p2.x, p2.y);
      if ( p2d_same(&p1, &p2) )
      {
        LWDEBUGF(1, "Last point of edge %" LWTFMT_ELEMID
                    " matches ring vertex %d", isoe->edge_id, from);
        /* last point matches, let's check next non-equal one */
        for ( j=2; j<=epa->npoints; j++ )
        {
          getPoint2d_p(epa, epa->npoints - j, &p2);
          LWDEBUGF(1, "Edge %" LWTFMT_ELEMID " 'prev' point %d is %g,%g",
                      isoe->edge_id, epa->npoints - j, p2.x, p2.y);
          /* we won't check duplicated edge points */
          if ( p2d_same(&p1, &p2) ) continue;
          /* we assume there are no duplicated points in ring */
          getPoint2d_p(ring, from+1, &pt);
          LWDEBUGF(1, "Ring's point %d is %g,%g",
                      from+1, pt.x, pt.y);
          match = p2d_same(&pt, &p2);
          break; /* we want to check a single non-equal next vertex */
        }
      }
#if POSTGIS_DEBUG_LEVEL > 0
      if ( match ) {
        LWDEBUGF(1, "Prev point of edge %" LWTFMT_ELEMID
                    " matches ring vertex %d", isoe->edge_id, from+1);
      } else {
        LWDEBUGF(1, "Prev point of edge %" LWTFMT_ELEMID
                    " does not match ring vertex %d", isoe->edge_id, from+1);
      }
#endif
    }
 
    if ( match ) return i;
 
  }
 
  return -1;
}

References LWT_ISO_EDGE::edge_id, LWT_ISO_EDGE::face_left, LWT_ISO_EDGE::face_right, LWT_ISO_EDGE::geom, getPoint2d_p(), LWDEBUG, LWDEBUGF, lwgeom_to_wkt(), lwline_as_lwgeom(), LWTFMT_ELEMID, POINTARRAY::npoints, p2d_same(), LWLINE::points, WKT_EXTENDED, POINT2D::x, and POINT2D::y.

Referenced by lwt_GetFaceEdges().

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