PostGIS  2.5.0dev-r@@SVN_REVISION@@

◆ lwt_GetNodeByPoint()

LWT_ELEMID lwt_GetNodeByPoint ( LWT_TOPOLOGY topo,
LWPOINT pt,
double  tol 
)

Retrieve the id of a node at a point location.

Parameters
topothe topology to operate on
pointthe point to use for query
tolmax distance around the given point to look for a node
Returns
a node identifier if one is found, 0 if none is found, -1 on error (multiple nodes within distance). The liblwgeom error handler will be invoked in case of error.

Definition at line 4833 of file lwgeom_topo.c.

References _lwt_release_nodes(), LWT_TOPOLOGY_T::be_iface, getPoint2d_p(), lwerror(), lwt_be_getNodeWithinDistance2D(), lwt_be_lastErrorMessage(), LWT_COL_NODE_GEOM, LWT_COL_NODE_NODE_ID, LWT_ISO_NODE::node_id, and LWPOINT::point.

4834 {
4835  LWT_ISO_NODE *elem;
4836  int num;
4837  int flds = LWT_COL_NODE_NODE_ID|LWT_COL_NODE_GEOM; /* geom not needed */
4838  LWT_ELEMID id = 0;
4839  POINT2D qp; /* query point */
4840 
4841  if ( ! getPoint2d_p(pt->point, 0, &qp) )
4842  {
4843  lwerror("Empty query point");
4844  return -1;
4845  }
4846  elem = lwt_be_getNodeWithinDistance2D(topo, pt, tol, &num, flds, 0);
4847  if ( num == -1 )
4848  {
4849  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
4850  return -1;
4851  }
4852  else if ( num )
4853  {
4854  if ( num > 1 )
4855  {
4856  _lwt_release_nodes(elem, num);
4857  lwerror("Two or more nodes found");
4858  return -1;
4859  }
4860  id = elem[0].node_id;
4861  _lwt_release_nodes(elem, num);
4862  }
4863 
4864  return id;
4865 }
static void _lwt_release_nodes(LWT_ISO_NODE *nodes, int num_nodes)
Definition: lwgeom_topo.c:467
LWT_ISO_NODE * lwt_be_getNodeWithinDistance2D(LWT_TOPOLOGY *topo, LWPOINT *pt, double dist, int *numelems, int fields, int limit)
Definition: lwgeom_topo.c:163
POINTARRAY * point
Definition: liblwgeom.h:413
const LWT_BE_IFACE * be_iface
LWT_ELEMID node_id
#define LWT_COL_NODE_NODE_ID
Node fields.
int getPoint2d_p(const POINTARRAY *pa, uint32_t n, POINT2D *point)
Definition: lwgeom_api.c:338
#define LWT_COL_NODE_GEOM
LWT_INT64 LWT_ELEMID
Identifier of topology element.
const char * lwt_be_lastErrorMessage(const LWT_BE_IFACE *be)
Definition: lwgeom_topo.c:120
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
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