PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ geography_azimuth()

Datum geography_azimuth ( PG_FUNCTION_ARGS  )

Definition at line 997 of file geography_measurement.c.

References geography_segmentize(), gserialized_get_srid(), gserialized_get_type(), lwgeom_as_lwpoint(), lwgeom_azumith_spheroid(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_is_empty(), PG_FUNCTION_INFO_V1(), POINTTYPE, and s.

Referenced by geography_project().

998 {
999  LWGEOM *lwgeom1 = NULL;
1000  LWGEOM *lwgeom2 = NULL;
1001  GSERIALIZED *g1 = NULL;
1002  GSERIALIZED *g2 = NULL;
1003  double azimuth;
1004  SPHEROID s;
1005  uint32_t type1, type2;
1006 
1007  /* Get our geometry object loaded into memory. */
1008  g1 = PG_GETARG_GSERIALIZED_P(0);
1009  g2 = PG_GETARG_GSERIALIZED_P(1);
1010 
1011  /* Only return for points. */
1012  type1 = gserialized_get_type(g1);
1013  type2 = gserialized_get_type(g2);
1014  if ( type1 != POINTTYPE || type2 != POINTTYPE )
1015  {
1016  elog(ERROR, "ST_Azimuth(geography, geography) is only valid for point inputs");
1017  PG_RETURN_NULL();
1018  }
1019 
1020  lwgeom1 = lwgeom_from_gserialized(g1);
1021  lwgeom2 = lwgeom_from_gserialized(g2);
1022 
1023  /* EMPTY things cannot be used */
1024  if ( lwgeom_is_empty(lwgeom1) || lwgeom_is_empty(lwgeom2) )
1025  {
1026  lwgeom_free(lwgeom1);
1027  lwgeom_free(lwgeom2);
1028  elog(ERROR, "ST_Azimuth(geography, geography) cannot work with empty points");
1029  PG_RETURN_NULL();
1030  }
1031 
1032  /* Initialize spheroid */
1033  spheroid_init_from_srid(fcinfo, gserialized_get_srid(g1), &s);
1034 
1035  /* Calculate the direction */
1036  azimuth = lwgeom_azumith_spheroid(lwgeom_as_lwpoint(lwgeom1), lwgeom_as_lwpoint(lwgeom2), &s);
1037 
1038  /* Clean up */
1039  lwgeom_free(lwgeom1);
1040  lwgeom_free(lwgeom2);
1041 
1042  PG_FREE_IF_COPY(g1, 0);
1043  PG_FREE_IF_COPY(g2, 1);
1044 
1045  /* Return NULL for unknown (same point) azimuth */
1046  if( isnan(azimuth) )
1047  {
1048  PG_RETURN_NULL();
1049  }
1050 
1051  PG_RETURN_FLOAT8(azimuth);
1052 }
uint32_t gserialized_get_type(const GSERIALIZED *s)
Extract the geometry type from the serialized form (it hides in the anonymous data area...
Definition: g_serialized.c:55
double lwgeom_azumith_spheroid(const LWPOINT *r, const LWPOINT *s, const SPHEROID *spheroid)
Calculate the bearing between two points on a spheroid.
Definition: lwgeodetic.c:2050
LWGEOM * lwgeom_from_gserialized(const GSERIALIZED *g)
Allocate a new LWGEOM from a GSERIALIZED.
void lwgeom_free(LWGEOM *geom)
Definition: lwgeom.c:1050
LWPOINT * lwgeom_as_lwpoint(const LWGEOM *lwgeom)
Definition: lwgeom.c:80
char * s
Definition: cu_in_wkt.c:23
#define POINTTYPE
LWTYPE numbers, used internally by PostGIS.
Definition: liblwgeom.h:70
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:1297
int32_t gserialized_get_srid(const GSERIALIZED *s)
Extract the SRID from the serialized form (it is packed into three bytes so this is a handy function)...
Definition: g_serialized.c:69
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