lwt_ChangeEdgeGeom()

int lwt_ChangeEdgeGeom	(	LWT_TOPOLOGY *	topo,
		LWT_ELEMID	edge,
		LWLINE *	curve
	)

Changes the shape of an edge without affecting the topology structure.

For ST_ChangeEdgeGeom

Parameters

topo	the topology to operate on
curve	the edge geometry

Returns

0 on success, -1 on error (liblwgeom error handler will be invoked with error message)

Definition at line 3179 of file lwgeom_topo.c.

{
  LWT_ISO_EDGE *oldedge;
  LWT_ISO_EDGE newedge;
  POINT2D p1, p2, pt;
  int i;
  int isclosed = 0;
 
  /* curve must be simple */
  if ( ! lwgeom_is_simple(lwline_as_lwgeom(geom)) )
  {
    lwerror("SQL/MM Spatial exception - curve not simple");
    return -1;
  }
 
  i = 1;
  oldedge = lwt_be_getEdgeById(topo, &edge_id, &i, LWT_COL_EDGE_ALL);
  if ( ! oldedge )
  {
    LWDEBUGF(1, "lwt_ChangeEdgeGeom: "
                "lwt_be_getEdgeById returned NULL and set i=%d", i);
    if ( i == -1 )
    {
      lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
      return -1;
    }
    else if ( i == 0 )
    {
      lwerror("SQL/MM Spatial exception - non-existent edge %"
              LWTFMT_ELEMID, edge_id);
      return -1;
    }
    else
    {
      lwerror("Backend coding error: getEdgeById callback returned NULL "
              "but numelements output parameter has value %d "
              "(expected 0 or 1)", i);
      return -1;
    }
  }
 
  LWDEBUGF(1, "lwt_ChangeEdgeGeom: "
              "old edge has %d points, new edge has %d points",
              oldedge->geom->points->npoints, geom->points->npoints);
 
  /*
   * e) Check StartPoint consistency
   */
  getPoint2d_p(oldedge->geom->points, 0, &p1);
  getPoint2d_p(geom->points, 0, &pt);
  if ( ! p2d_same(&p1, &pt) )
  {
    _lwt_release_edges(oldedge, 1);
    lwerror("SQL/MM Spatial exception - "
            "start node not geometry start point.");
    return -1;
  }
 
  /*
   * f) Check EndPoint consistency
   */
  if ( oldedge->geom->points->npoints < 2 )
  {
    _lwt_release_edges(oldedge, 1);
    lwerror("Corrupted topology: edge %" LWTFMT_ELEMID
            " has less than 2 vertices", oldedge->edge_id);
    return -1;
  }
  getPoint2d_p(oldedge->geom->points, oldedge->geom->points->npoints-1, &p2);
  if ( geom->points->npoints < 2 )
  {
    _lwt_release_edges(oldedge, 1);
    lwerror("Invalid edge: less than 2 vertices");
    return -1;
  }
  getPoint2d_p(geom->points, geom->points->npoints-1, &pt);
  if ( ! p2d_same(&pt, &p2) )
  {
    _lwt_release_edges(oldedge, 1);
    lwerror("SQL/MM Spatial exception - "
            "end node not geometry end point.");
    return -1;
  }
 
  /* Not in the specs:
   * if the edge is closed, check we didn't change winding !
   *       (should be part of isomorphism checking)
   */
  if ( oldedge->start_node == oldedge->end_node )
  {
    isclosed = 1;
#if 1 /* TODO: this is actually bogus as a test */
    /* check for valid edge (distinct vertices must exist) */
    if ( ! _lwt_GetInteriorEdgePoint(geom, &pt) )
    {
      _lwt_release_edges(oldedge, 1);
      lwerror("Invalid edge (no two distinct vertices exist)");
      return -1;
    }
#endif
 
    if ( ptarray_isccw(oldedge->geom->points) !=
         ptarray_isccw(geom->points) )
    {
      _lwt_release_edges(oldedge, 1);
      lwerror("Edge twist at node POINT(%g %g)", p1.x, p1.y);
      return -1;
    }
  }
 
  if ( _lwt_CheckEdgeCrossing(topo, oldedge->start_node,
                                    oldedge->end_node, geom, edge_id ) )
  {
    /* would have called lwerror already, leaking :( */
    _lwt_release_edges(oldedge, 1);
    return -1;
  }
 
  LWDEBUG(1, "lwt_ChangeEdgeGeom: "
             "edge crossing check passed ");
 
  /*
   * Not in the specs:
   * Check topological isomorphism
   */
 
  /* Check that the "motion range" doesn't include any node */
  // 1. compute combined bbox of old and new edge
  GBOX mbox; /* motion box */
  lwgeom_add_bbox((LWGEOM*)oldedge->geom); /* just in case */
  lwgeom_add_bbox((LWGEOM*)geom); /* just in case */
  gbox_union(oldedge->geom->bbox, geom->bbox, &mbox);
  // 2. fetch all nodes in the combined box
  LWT_ISO_NODE *nodes;
  int numnodes;
  nodes = lwt_be_getNodeWithinBox2D(topo, &mbox, &numnodes,
                                          LWT_COL_NODE_ALL, 0);
  LWDEBUGF(1, "lwt_be_getNodeWithinBox2D returned %d nodes", numnodes);
  if ( numnodes == -1 ) {
    _lwt_release_edges(oldedge, 1);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  // 3. if any node beside endnodes are found:
  if ( numnodes > ( 1 + isclosed ? 0 : 1 ) )
  {{
    //   3.2. bail out if any node is in one and not the other
    for (i=0; i<numnodes; ++i)
    {
      LWT_ISO_NODE *n = &(nodes[i]);
      if ( n->node_id == oldedge->start_node ) continue;
      if ( n->node_id == oldedge->end_node ) continue;
      const POINT2D *pt = getPoint2d_cp(n->geom->point, 0);
      int ocont = ptarray_contains_point_partial(oldedge->geom->points, pt, isclosed, NULL) == LW_INSIDE;
      int ncont = ptarray_contains_point_partial(geom->points, pt, isclosed, NULL) == LW_INSIDE;
      if (ocont != ncont)
      {
        size_t sz;
        char *wkt = lwgeom_to_wkt(lwpoint_as_lwgeom(n->geom), WKT_ISO, 15, &sz);
        _lwt_release_nodes(nodes, numnodes);
        lwerror("Edge motion collision at %s", wkt);
        lwfree(wkt); /* would not necessarely reach this point */
        return -1;
      }
    }
  }}
  if ( numnodes ) _lwt_release_nodes(nodes, numnodes);
 
  LWDEBUG(1, "nodes containment check passed");
 
  /*
   * Check edge adjacency before
   * TODO: can be optimized to gather azimuths of all edge ends once
   */
 
  edgeend span_pre, epan_pre;
  /* initialize span_pre.myaz and epan_pre.myaz with existing edge */
  i = _lwt_InitEdgeEndByLine(&span_pre, &epan_pre,
                             oldedge->geom, &p1, &p2);
  if ( i ) return -1; /* lwerror should have been raised */
  _lwt_FindAdjacentEdges( topo, oldedge->start_node, &span_pre,
                                  isclosed ? &epan_pre : NULL, edge_id );
  _lwt_FindAdjacentEdges( topo, oldedge->end_node, &epan_pre,
                                  isclosed ? &span_pre : NULL, edge_id );
 
  LWDEBUGF(1, "edges adjacent to old edge are %" LWTFMT_ELEMID
              " and %" LWTFMT_ELEMID " (first point), %" LWTFMT_ELEMID
              " and %" LWTFMT_ELEMID " (last point)",
              span_pre.nextCW, span_pre.nextCCW,
              epan_pre.nextCW, epan_pre.nextCCW);
 
  /* update edge geometry */
  newedge.edge_id = edge_id;
  newedge.geom = geom;
  i = lwt_be_updateEdgesById(topo, &newedge, 1, LWT_COL_EDGE_GEOM);
  if ( i == -1 )
  {
    _lwt_release_edges(oldedge, 1);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  if ( ! i )
  {
    _lwt_release_edges(oldedge, 1);
    lwerror("Unexpected error: %d edges updated when expecting 1", i);
    return -1;
  }
 
  /*
   * Check edge adjacency after
   */
  edgeend span_post, epan_post;
  i = _lwt_InitEdgeEndByLine(&span_post, &epan_post, geom, &p1, &p2);
  if ( i ) return -1; /* lwerror should have been raised */
  /* initialize epan_post.myaz and epan_post.myaz */
  i = _lwt_InitEdgeEndByLine(&span_post, &epan_post,
                             geom, &p1, &p2);
  if ( i ) return -1; /* lwerror should have been raised */
  _lwt_FindAdjacentEdges( topo, oldedge->start_node, &span_post,
                          isclosed ? &epan_post : NULL, edge_id );
  _lwt_FindAdjacentEdges( topo, oldedge->end_node, &epan_post,
                          isclosed ? &span_post : NULL, edge_id );
 
  LWDEBUGF(1, "edges adjacent to new edge are %" LWTFMT_ELEMID
              " and %" LWTFMT_ELEMID " (first point), %" LWTFMT_ELEMID
              " and %" LWTFMT_ELEMID " (last point)",
              span_pre.nextCW, span_pre.nextCCW,
              epan_pre.nextCW, epan_pre.nextCCW);
 
 
  /* Bail out if next CW or CCW edge on start node changed */
  if ( span_pre.nextCW != span_post.nextCW ||
       span_pre.nextCCW != span_post.nextCCW )
  {{
    LWT_ELEMID nid = oldedge->start_node;
    _lwt_release_edges(oldedge, 1);
    lwerror("Edge changed disposition around start node %"
            LWTFMT_ELEMID, nid);
    return -1;
  }}
 
  /* Bail out if next CW or CCW edge on end node changed */
  if ( epan_pre.nextCW != epan_post.nextCW ||
       epan_pre.nextCCW != epan_post.nextCCW )
  {{
    LWT_ELEMID nid = oldedge->end_node;
    _lwt_release_edges(oldedge, 1);
    lwerror("Edge changed disposition around end node %"
            LWTFMT_ELEMID, nid);
    return -1;
  }}
 
  /*
  -- Update faces MBR of left and right faces
  -- TODO: think about ways to optimize this part, like see if
  --       the old edge geometry participated in the definition
  --       of the current MBR (for shrinking) or the new edge MBR
  --       would be larger than the old face MBR...
  --
  */
  const GBOX* oldbox = lwgeom_get_bbox(lwline_as_lwgeom(oldedge->geom));
  const GBOX* newbox = lwgeom_get_bbox(lwline_as_lwgeom(geom));
  if ( ! gbox_same(oldbox, newbox) )
  {{
    int facestoupdate = 0;
    LWT_ISO_FACE faces[2];
    LWGEOM *nface1 = NULL;
    LWGEOM *nface2 = NULL;
    if ( oldedge->face_left > 0 )
    {
      nface1 = lwt_GetFaceGeometry(topo, oldedge->face_left);
      if ( ! nface1 )
      {
        lwerror("lwt_ChangeEdgeGeom could not construct face %"
                   LWTFMT_ELEMID ", on the left of edge %" LWTFMT_ELEMID,
                  oldedge->face_left, edge_id);
        return -1;
      }
  #if 0
      {
      size_t sz;
      char *wkt = lwgeom_to_wkt(nface1, WKT_EXTENDED, 2, &sz);
      LWDEBUGF(1, "new geometry of face left (%d): %s", (int)oldedge->face_left, wkt);
      lwfree(wkt);
      }
  #endif
      lwgeom_add_bbox(nface1);
      if ( ! nface1->bbox )
      {
        lwerror("Corrupted topology: face %d, left of edge %d, has no bbox",
          oldedge->face_left, edge_id);
        return -1;
      }
      faces[facestoupdate].face_id = oldedge->face_left;
      /* ownership left to nface */
      faces[facestoupdate++].mbr = nface1->bbox;
    }
    if ( oldedge->face_right > 0
         /* no need to update twice the same face.. */
         && oldedge->face_right != oldedge->face_left )
    {
      nface2 = lwt_GetFaceGeometry(topo, oldedge->face_right);
      if ( ! nface2 )
      {
        lwerror("lwt_ChangeEdgeGeom could not construct face %"
                   LWTFMT_ELEMID ", on the right of edge %" LWTFMT_ELEMID,
                  oldedge->face_right, edge_id);
        return -1;
      }
  #if 0
      {
      size_t sz;
      char *wkt = lwgeom_to_wkt(nface2, WKT_EXTENDED, 2, &sz);
      LWDEBUGF(1, "new geometry of face right (%d): %s", (int)oldedge->face_right, wkt);
      lwfree(wkt);
      }
  #endif
      lwgeom_add_bbox(nface2);
      if ( ! nface2->bbox )
      {
        lwerror("Corrupted topology: face %d, right of edge %d, has no bbox",
          oldedge->face_right, edge_id);
        return -1;
      }
      faces[facestoupdate].face_id = oldedge->face_right;
      faces[facestoupdate++].mbr = nface2->bbox; /* ownership left to nface */
    }
    LWDEBUGF(1, "%d faces to update", facestoupdate);
    if ( facestoupdate )
    {
      i = lwt_be_updateFacesById( topo, &(faces[0]), facestoupdate );
      if ( i != facestoupdate )
      {
        if ( nface1 ) lwgeom_free(nface1);
        if ( nface2 ) lwgeom_free(nface2);
        _lwt_release_edges(oldedge, 1);
        if ( i == -1 )
          lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
        else
          lwerror("Unexpected error: %d faces found when expecting 1", i);
        return -1;
      }
    }
    if ( nface1 ) lwgeom_free(nface1);
    if ( nface2 ) lwgeom_free(nface2);
  }} else {{
    lwnotice("BBOX of changed edge did not change");
  }}
 
  LWDEBUG(1, "all done, cleaning up edges");
 
  _lwt_release_edges(oldedge, 1);
  return 0; /* success */
}

References _lwt_CheckEdgeCrossing(), _lwt_FindAdjacentEdges(), _lwt_GetInteriorEdgePoint(), _lwt_InitEdgeEndByLine(), _lwt_release_edges(), _lwt_release_nodes(), LWGEOM::bbox, LWLINE::bbox, LWT_TOPOLOGY_T::be_iface, LWT_ISO_EDGE::edge_id, LWT_ISO_EDGE::end_node, LWT_ISO_FACE::face_id, LWT_ISO_EDGE::face_left, LWT_ISO_EDGE::face_right, gbox_same(), gbox_union(), LWT_ISO_NODE::geom, LWT_ISO_EDGE::geom, getPoint2d_cp(), getPoint2d_p(), LW_INSIDE, LWDEBUG, LWDEBUGF, lwerror(), lwfree(), lwgeom_add_bbox(), lwgeom_free(), lwgeom_get_bbox(), lwgeom_is_simple(), lwgeom_to_wkt(), lwline_as_lwgeom(), lwnotice(), lwpoint_as_lwgeom(), lwt_be_getEdgeById(), lwt_be_getNodeWithinBox2D(), lwt_be_lastErrorMessage(), lwt_be_updateEdgesById(), lwt_be_updateFacesById(), LWT_COL_EDGE_ALL, LWT_COL_EDGE_GEOM, LWT_COL_NODE_ALL, lwt_GetFaceGeometry(), LWTFMT_ELEMID, LWT_ISO_FACE::mbr, edgeend_t::nextCCW, edgeend_t::nextCW, LWT_ISO_NODE::node_id, POINTARRAY::npoints, p2d_same(), LWPOINT::point, LWLINE::points, ptarray_contains_point_partial(), ptarray_isccw(), LWT_ISO_EDGE::start_node, WKT_EXTENDED, WKT_ISO, POINT2D::x, and POINT2D::y.

Referenced by _lwt_AddPoint().

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