PostGIS  3.0.6dev-r@@SVN_REVISION@@

◆ geography_segmentize()

Datum geography_segmentize ( PG_FUNCTION_ARGS  )

Definition at line 1118 of file geography_measurement.c.

1119 {
1120  LWGEOM *lwgeom1 = NULL;
1121  LWGEOM *lwgeom2 = NULL;
1122  GSERIALIZED *g1 = NULL;
1123  GSERIALIZED *g2 = NULL;
1124  double max_seg_length;
1125  uint32_t type1;
1126 
1127  /* Get our geometry object loaded into memory. */
1128  g1 = PG_GETARG_GSERIALIZED_P(0);
1129  type1 = gserialized_get_type(g1);
1130 
1131  /* Convert max_seg_length from metric units to radians */
1132  max_seg_length = PG_GETARG_FLOAT8(1) / WGS84_RADIUS;
1133 
1134  /* We can't densify points or points, reflect them back */
1135  if ( type1 == POINTTYPE || type1 == MULTIPOINTTYPE || gserialized_is_empty(g1) )
1136  PG_RETURN_POINTER(g1);
1137 
1138  /* Deserialize */
1139  lwgeom1 = lwgeom_from_gserialized(g1);
1140 
1141  /* Calculate the densified geometry */
1142  lwgeom2 = lwgeom_segmentize_sphere(lwgeom1, max_seg_length);
1143 
1144  /*
1145  ** Set the geodetic flag so subsequent
1146  ** functions do the right thing.
1147  */
1148  lwgeom_set_geodetic(lwgeom2, true);
1149 
1150  /* Recalculate the boxes after re-setting the geodetic bit */
1151  lwgeom_drop_bbox(lwgeom2);
1152 
1153  /* We are trusting geography_serialize will add a box if needed */
1154  g2 = geography_serialize(lwgeom2);
1155 
1156  /* Clean up */
1157  lwgeom_free(lwgeom1);
1158  lwgeom_free(lwgeom2);
1159  PG_FREE_IF_COPY(g1, 0);
1160 
1161  PG_RETURN_POINTER(g2);
1162 }
LWGEOM * lwgeom_from_gserialized(const GSERIALIZED *g)
Allocate a new LWGEOM from a GSERIALIZED.
Definition: gserialized.c:239
int gserialized_is_empty(const GSERIALIZED *g)
Check if a GSERIALIZED is empty without deserializing first.
Definition: gserialized.c:152
uint32_t gserialized_get_type(const GSERIALIZED *g)
Extract the geometry type from the serialized form (it hides in the anonymous data area,...
Definition: gserialized.c:89
void lwgeom_set_geodetic(LWGEOM *geom, int value)
Set the FLAGS geodetic bit on geometry an all sub-geometries and pointlists.
Definition: lwgeom.c:946
LWGEOM * lwgeom_segmentize_sphere(const LWGEOM *lwg_in, double max_seg_length)
Derive a new geometry with vertices added to ensure no vertex is more than max_seg_length (in radians...
Definition: lwgeodetic.c:1743
void lwgeom_free(LWGEOM *geom)
Definition: lwgeom.c:1138
#define WGS84_RADIUS
Definition: liblwgeom.h:162
#define MULTIPOINTTYPE
Definition: liblwgeom.h:119
#define POINTTYPE
LWTYPE numbers, used internally by PostGIS.
Definition: liblwgeom.h:116
void lwgeom_drop_bbox(LWGEOM *lwgeom)
Call this function to drop BBOX and SRID from LWGEOM.
Definition: lwgeom.c:664

References gserialized_get_type(), gserialized_is_empty(), lwgeom_drop_bbox(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_segmentize_sphere(), lwgeom_set_geodetic(), MULTIPOINTTYPE, POINTTYPE, and WGS84_RADIUS.

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