PostGIS  2.3.8dev-r@@SVN_REVISION@@

◆ lwt_GetEdgeByPoint()

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

Find the edge-id of an edge that intersects a given point.

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

Definition at line 4824 of file lwgeom_topo.c.

References _lwt_release_edges(), LWT_TOPOLOGY_T::be_iface, LWT_ISO_EDGE::edge_id, LWT_ISO_EDGE::geom, lwerror(), lwgeom_is_empty(), lwgeom_mindistance2d_tolerance(), lwline_as_lwgeom(), lwnotice(), lwpoint_as_lwgeom(), lwt_be_getEdgeWithinDistance2D(), lwt_be_lastErrorMessage(), LWT_COL_EDGE_EDGE_ID, LWT_COL_EDGE_GEOM, and LWTFMT_ELEMID.

4825 {
4826  LWT_ISO_EDGE *elem;
4827  int num, i;
4828  int flds = LWT_COL_EDGE_EDGE_ID|LWT_COL_EDGE_GEOM; /* GEOM is not needed */
4829  LWT_ELEMID id = 0;
4830  LWGEOM *qp = lwpoint_as_lwgeom(pt); /* query point */
4831 
4832  if ( lwgeom_is_empty(qp) )
4833  {
4834  lwerror("Empty query point");
4835  return -1;
4836  }
4837  elem = lwt_be_getEdgeWithinDistance2D(topo, pt, tol, &num, flds, 0);
4838  if ( num == -1 )
4839  {
4840  lwerror("Backend error: %s", lwt_be_lastErrorMessage(topo->be_iface));
4841  return -1;
4842  }
4843  for (i=0; i<num;++i)
4844  {
4845  LWT_ISO_EDGE *e = &(elem[i]);
4846 #if 0
4847  LWGEOM* geom;
4848  double dist;
4849 
4850  if ( ! e->geom )
4851  {
4852  _lwt_release_edges(elem, num);
4853  lwnotice("Corrupted topology: edge %" LWTFMT_ELEMID
4854  " has null geometry", e->edge_id);
4855  continue;
4856  }
4857 
4858  /* Should we check for intersection not being on an endpoint
4859  * as documented ? */
4860  geom = lwline_as_lwgeom(e->geom);
4861  dist = lwgeom_mindistance2d_tolerance(geom, qp, tol);
4862  if ( dist > tol ) continue;
4863 #endif
4864 
4865  if ( id )
4866  {
4867  _lwt_release_edges(elem, num);
4868  lwerror("Two or more edges found");
4869  return -1;
4870  }
4871  else id = e->edge_id;
4872  }
4873 
4874  if ( num ) _lwt_release_edges(elem, num);
4875 
4876  return id;
4877 }
void lwnotice(const char *fmt,...)
Write a notice out to the notice handler.
Definition: lwutil.c:89
double lwgeom_mindistance2d_tolerance(const LWGEOM *lw1, const LWGEOM *lw2, double tolerance)
Function handling min distance calculations and dwithin calculations.
Definition: measures.c:213
LWLINE * geom
LWGEOM * lwline_as_lwgeom(const LWLINE *obj)
Definition: lwgeom.c:262
const LWT_BE_IFACE * be_iface
LWT_ELEMID edge_id
#define LWT_COL_EDGE_EDGE_ID
Edge fields.
static void _lwt_release_edges(LWT_ISO_EDGE *edges, int num_edges)
Definition: lwgeom_topo.c:467
LWT_ISO_EDGE * lwt_be_getEdgeWithinDistance2D(LWT_TOPOLOGY *topo, LWPOINT *pt, double dist, int *numelems, int fields, int limit)
Definition: lwgeom_topo.c:260
LWGEOM * lwpoint_as_lwgeom(const LWPOINT *obj)
Definition: lwgeom.c:267
LWT_INT64 LWT_ELEMID
Identifier of topology element.
#define LWT_COL_EDGE_GEOM
int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members) ...
Definition: lwgeom.c:1310
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:102
#define LWTFMT_ELEMID
Definition: lwgeom_topo.c:44
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