PostGIS  2.5.7dev-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 4647 of file lwgeom_topo.c.

4648 {
4649  LWT_ISO_NODE *elem;
4650  int num;
4651  int flds = LWT_COL_NODE_NODE_ID|LWT_COL_NODE_GEOM; /* geom not needed */
4652  LWT_ELEMID id = 0;
4653  POINT2D qp; /* query point */
4654 
4655  if ( ! getPoint2d_p(pt->point, 0, &qp) )
4656  {
4657  lwerror("Empty query point");
4658  return -1;
4659  }
4660  elem = lwt_be_getNodeWithinDistance2D(topo, pt, tol, &num, flds, 0);
4661  if ( num == -1 )
4662  {
4663  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
4664  return -1;
4665  }
4666  else if ( num )
4667  {
4668  if ( num > 1 )
4669  {
4670  _lwt_release_nodes(elem, num);
4671  lwerror("Two or more nodes found");
4672  return -1;
4673  }
4674  id = elem[0].node_id;
4675  _lwt_release_nodes(elem, num);
4676  }
4677 
4678  return id;
4679 }
int getPoint2d_p(const POINTARRAY *pa, uint32_t n, POINT2D *point)
Definition: lwgeom_api.c:348
LWT_INT64 LWT_ELEMID
Identifier of topology element.
#define LWT_COL_NODE_GEOM
#define LWT_COL_NODE_NODE_ID
Node fields.
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
const char * lwt_be_lastErrorMessage(const LWT_BE_IFACE *be)
Definition: lwgeom_topo.c:120
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:414
LWT_ELEMID node_id
const LWT_BE_IFACE * be_iface

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.

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