lwt_ModEdgeSplit()

LWT_ELEMID lwt_ModEdgeSplit	(	LWT_TOPOLOGY *	topo,
		LWT_ELEMID	edge,
		LWPOINT *	pt,
		int	skipChecks
	)

Split an edge by a node, modifying the original edge and adding a new one.

For ST_ModEdgeSplit

Parameters

topo	the topology to operate on
edge	identifier of the edge to be split
pt	geometry of the new node
skipChecks	if non-zero skips consistency checks (coincident node, point not on edge...)

Returns

the id of newly created node, or -1 on error (liblwgeom error handler will be invoked with error message)

Definition at line 1019 of file lwgeom_topo.c.

{
  LWT_ISO_NODE node;
  LWT_ISO_EDGE* oldedge = NULL;
  LWCOLLECTION *split_col;
  const LWGEOM *oldedge_geom;
  const LWGEOM *newedge_geom;
  LWT_ISO_EDGE newedge1;
  LWT_ISO_EDGE seledge, updedge, excedge;
  int ret;
 
  split_col = _lwt_EdgeSplit( topo, edge, pt, skipISOChecks, &oldedge );
  if ( ! split_col ) return -1; /* should have raised an exception */
  oldedge_geom = split_col->geoms[0];
  newedge_geom = split_col->geoms[1];
  /* Make sure the SRID is set on the subgeom */
  ((LWGEOM*)oldedge_geom)->srid = split_col->srid;
  ((LWGEOM*)newedge_geom)->srid = split_col->srid;
 
  /* Add new node, getting new id back */
  node.node_id = -1;
  node.containing_face = -1; /* means not-isolated */
  node.geom = pt;
  if ( ! lwt_be_insertNodes(topo, &node, 1) )
  {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  if (node.node_id == -1) {
    /* should have been set by backend */
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend coding error: "
            "insertNodes callback did not return node_id");
    return -1;
  }
 
  /* Insert the new edge */
  newedge1.edge_id = lwt_be_getNextEdgeId(topo);
  if ( newedge1.edge_id == -1 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
  newedge1.start_node = node.node_id;
  newedge1.end_node = oldedge->end_node;
  newedge1.face_left = oldedge->face_left;
  newedge1.face_right = oldedge->face_right;
  newedge1.next_left = oldedge->next_left == -oldedge->edge_id ?
      -newedge1.edge_id : oldedge->next_left;
  newedge1.next_right = -oldedge->edge_id;
  newedge1.geom = lwgeom_as_lwline(newedge_geom);
  /* lwgeom_split of a line should only return lines ... */
  if ( ! newedge1.geom ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("first geometry in lwgeom_split output is not a line");
    return -1;
  }
  ret = lwt_be_insertEdges(topo, &newedge1, 1);
  if ( ret == -1 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  } else if ( ret == 0 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Insertion of split edge failed (no reason)");
    return -1;
  }
 
  /* Update the old edge */
  updedge.geom = lwgeom_as_lwline(oldedge_geom);
  /* lwgeom_split of a line should only return lines ... */
  if ( ! updedge.geom ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("second geometry in lwgeom_split output is not a line");
    return -1;
  }
  updedge.next_left = newedge1.edge_id;
  updedge.end_node = node.node_id;
  ret = lwt_be_updateEdges(topo,
      oldedge, LWT_COL_EDGE_EDGE_ID,
      &updedge, LWT_COL_EDGE_GEOM|LWT_COL_EDGE_NEXT_LEFT|LWT_COL_EDGE_END_NODE,
      NULL, 0);
  if ( ret == -1 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  } else if ( ret == 0 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Edge being split (%d) disappeared during operations?", oldedge->edge_id);
    return -1;
  } else if ( ret > 1 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("More than a single edge found with id %d !", oldedge->edge_id);
    return -1;
  }
 
  /* Update all next edge references to match new layout (ST_ModEdgeSplit) */
 
  updedge.next_right = -newedge1.edge_id;
  excedge.edge_id = newedge1.edge_id;
  seledge.next_right = -oldedge->edge_id;
  seledge.start_node = oldedge->end_node;
  ret = lwt_be_updateEdges(topo,
      &seledge, LWT_COL_EDGE_NEXT_RIGHT|LWT_COL_EDGE_START_NODE,
      &updedge, LWT_COL_EDGE_NEXT_RIGHT,
      &excedge, LWT_COL_EDGE_EDGE_ID);
  if ( ret == -1 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
 
  updedge.next_left = -newedge1.edge_id;
  excedge.edge_id = newedge1.edge_id;
  seledge.next_left = -oldedge->edge_id;
  seledge.end_node = oldedge->end_node;
  ret = lwt_be_updateEdges(topo,
      &seledge, LWT_COL_EDGE_NEXT_LEFT|LWT_COL_EDGE_END_NODE,
      &updedge, LWT_COL_EDGE_NEXT_LEFT,
      &excedge, LWT_COL_EDGE_EDGE_ID);
  if ( ret == -1 ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
 
  /* Update TopoGeometries composition */
  ret = lwt_be_updateTopoGeomEdgeSplit(topo, oldedge->edge_id, newedge1.edge_id, -1);
  if ( ! ret ) {
    _lwt_release_edges(oldedge, 1);
    lwcollection_free(split_col);
    lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
    return -1;
  }
 
  _lwt_release_edges(oldedge, 1);
  lwcollection_free(split_col);
 
  /* return new node id */
  return node.node_id;
}

References _lwt_EdgeSplit(), _lwt_release_edges(), LWT_TOPOLOGY_T::be_iface, LWT_ISO_NODE::containing_face, LWT_ISO_EDGE::edge_id, LWT_ISO_EDGE::end_node, LWT_ISO_EDGE::face_left, LWT_ISO_EDGE::face_right, LWT_ISO_NODE::geom, LWT_ISO_EDGE::geom, LWCOLLECTION::geoms, lwcollection_free(), lwerror(), lwgeom_as_lwline(), lwt_be_getNextEdgeId(), lwt_be_insertEdges(), lwt_be_insertNodes(), lwt_be_lastErrorMessage(), lwt_be_updateEdges(), lwt_be_updateTopoGeomEdgeSplit(), LWT_COL_EDGE_EDGE_ID, LWT_COL_EDGE_END_NODE, LWT_COL_EDGE_GEOM, LWT_COL_EDGE_NEXT_LEFT, LWT_COL_EDGE_NEXT_RIGHT, LWT_COL_EDGE_START_NODE, LWT_ISO_EDGE::next_left, LWT_ISO_EDGE::next_right, LWT_ISO_NODE::node_id, LWGEOM::srid, LWCOLLECTION::srid, and LWT_ISO_EDGE::start_node.

Referenced by _lwt_AddPoint().

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