PostGIS  3.1.6dev-r@@SVN_REVISION@@

◆ lwgeom_delaunay_triangulation()

LWGEOM* lwgeom_delaunay_triangulation ( const LWGEOM geom,
double  tolerance,
int32_t  edgeOnly 
)

Take vertices of a geometry and build a delaunay triangulation on them.

Parameters
geomthe input geometry
tolerancean optional snapping tolerance for improved robustness
edgeOnlyif non-zero the result will be a MULTILINESTRING, otherwise it'll be a COLLECTION of polygons.

Definition at line 1933 of file liblwgeom/lwgeom_geos.c.

1934 {
1935  LWGEOM* result;
1936  int32_t srid = RESULT_SRID(geom);
1937  uint8_t is3d = FLAGS_GET_Z(geom->flags);
1938  GEOSGeometry *g1, *g3;
1939 
1940  if (output < 0 || output > 2)
1941  {
1942  lwerror("%s: invalid output type specified %d", __func__, output);
1943  return NULL;
1944  }
1945 
1946  if (srid == SRID_INVALID) return NULL;
1947 
1948  initGEOS(lwnotice, lwgeom_geos_error);
1949 
1950  if (!(g1 = LWGEOM2GEOS(geom, AUTOFIX))) GEOS_FAIL();
1951 
1952  /* if output != 1 we want polys */
1953  g3 = GEOSDelaunayTriangulation(g1, tolerance, output == 1);
1954 
1955  if (!g3) GEOS_FREE_AND_FAIL(g1);
1956  GEOSSetSRID(g3, srid);
1957 
1958  if (output == 2)
1959  {
1960  result = (LWGEOM*)lwtin_from_geos(g3, is3d);
1961  if (!result)
1962  {
1963  GEOS_FREE(g1, g3);
1964  lwerror("%s: cannot convert output geometry", __func__);
1965  return NULL;
1966  }
1967  lwgeom_set_srid(result, srid);
1968  }
1969  else if (!(result = GEOS2LWGEOM(g3, is3d)))
1970  GEOS_FREE_AND_FAIL(g1, g3);
1971 
1972  GEOS_FREE(g1, g3);
1973  return result;
1974 }
char result[OUT_DOUBLE_BUFFER_SIZE]
Definition: cu_print.c:267
#define GEOS_FREE(...)
#define AUTOFIX
#define RESULT_SRID(...)
#define GEOS_FAIL()
#define GEOS_FREE_AND_FAIL(...)
GEOSGeometry * LWGEOM2GEOS(const LWGEOM *lwgeom, uint8_t autofix)
LWGEOM * GEOS2LWGEOM(const GEOSGeometry *geom, uint8_t want3d)
void lwgeom_geos_error(const char *fmt,...)
LWTIN * lwtin_from_geos(const GEOSGeometry *geom, uint8_t want3d)
#define SRID_INVALID
Definition: liblwgeom.h:233
void lwgeom_set_srid(LWGEOM *geom, int32_t srid)
Set the SRID on an LWGEOM For collections, only the parent gets an SRID, all the children get SRID_UN...
Definition: lwgeom.c:1530
#define FLAGS_GET_Z(flags)
Definition: liblwgeom.h:179
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
void lwnotice(const char *fmt,...)
Write a notice out to the notice handler.
Definition: lwutil.c:177
lwflags_t flags
Definition: liblwgeom.h:475

References AUTOFIX, LWGEOM::flags, FLAGS_GET_Z, GEOS2LWGEOM(), GEOS_FAIL, GEOS_FREE, GEOS_FREE_AND_FAIL, lwerror(), LWGEOM2GEOS(), lwgeom_geos_error(), lwgeom_set_srid(), lwnotice(), lwtin_from_geos(), result, RESULT_SRID, and SRID_INVALID.

Referenced by ST_DelaunayTriangles(), and test_lwgeom_delaunay_triangulation().

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