*
**********************************************************************/
-/*
+
+/**********************************************************************
** Spherical radius.
** Moritz, H. (1980). Geodetic Reference System 1980, by resolution of the XVII General Assembly of the IUGG in Canberra.
** http://en.wikipedia.org/wiki/Earth_radius
*/
#define WGS84_RADIUS 6371009.0
+/* For reference, the old value used in distance_sphere was 6370986.884258304 */
+
+
+/**********************************************************************
+** Useful functions for all GEOGRAPHY handlers.
+*/
+
+/* Convert lwgeom to newly allocated gserialized */
+GSERIALIZED* geography_serialize(LWGEOM *lwgeom);
+/* Check that the typmod matches the flags on the lwgeom */
+void geography_valid_typmod(LWGEOM *lwgeom, int32 typmod);
+/* Check that the type is legal in geography (no curves please!) */
+void geography_valid_type(uchar type);
+
+
/**********************************************************************
** GIDX structure.
*/
#define GIDX_MAX_SIZE 36
+/*********************************************************************************
+** GIDX support functions.
+**
+** We put the GIDX support here rather than libgeom because it is a specialized
+** type only used for indexing purposes. It also makes use of some PgSQL
+** infrastructure like the VARSIZE() macros.
+*/
-/* Useful functions for all GEOGRAPHY handlers. */
-GSERIALIZED* geography_serialize(LWGEOM *lwgeom);
-void geography_valid_typmod(LWGEOM *lwgeom, int32 typmod);
-void geography_valid_type(uchar type);
-int geography_datum_gidx(Datum geography_datum, GIDX *gidx);
+/* Returns number of dimensions for this GIDX */
+#define GIDX_NDIMS(gidx) ((VARSIZE((gidx)) - VARHDRSZ) / (2 * sizeof(float)))
+/* Minimum accessor. */
+#define GIDX_GET_MIN(gidx, dimension) ((gidx)->c[2*(dimension)])
+/* Maximum accessor. */
+#define GIDX_GET_MAX(gidx, dimension) ((gidx)->c[2*(dimension)+1])
+/* Minimum setter. */
+#define GIDX_SET_MIN(gidx, dimension, value) ((gidx)->c[2*(dimension)] = (value))
+/* Maximum setter. */
+#define GIDX_SET_MAX(gidx, dimension, value) ((gidx)->c[2*(dimension)+1] = (value))
+/* Returns the size required to store a GIDX of requested dimension */
+#define GIDX_SIZE(dimensions) (sizeof(int32) + 2*(dimensions)*sizeof(float))
+/* Allocate a new gidx */
GIDX* gidx_new(int ndims);
+/* Pull out the gidx bounding box with a absolute minimum system overhead */
+int geography_datum_gidx(Datum geography_datum, GIDX *gidx);
+/* Convert a gidx to a gbox */
void gbox_from_gidx(GIDX *gidx, GBOX *gbox);
+/* Convert a gbox to a new gidx */
+GIDX* gidx_from_gbox(GBOX box);
+/* Copy a new bounding box into an existing gserialized */
+GSERIALIZED* gidx_insert_into_gserialized(GSERIALIZED *g, GIDX *gidx);
+
+
+
+
-- Availability: 1.5.0
-- ---------- ---------- ---------- ---------- ---------- ---------- ----------
--- Stop calculation and return once distance is less than tolerance
+-- Stop calculation and return immediately once distance is less than tolerance
+-- Availability: 1.5.0
CREATE OR REPLACE FUNCTION _ST_Distance(geography, geography, float8)
RETURNS float8
AS 'MODULE_PATHNAME','geography_distance_sphere'
LANGUAGE 'C' IMMUTABLE STRICT;
+-- Availability: 1.5.0
CREATE OR REPLACE FUNCTION ST_Distance(geography, geography)
RETURNS float8
AS 'SELECT _ST_Distance($1, $2, 0.0)'
LANGUAGE 'SQL' IMMUTABLE STRICT;
+-- Only expands the bounding box, the actual geometry will remain unchanged, use with care.
+-- Availability: 1.5.0
+CREATE OR REPLACE FUNCTION _ST_Expand(geography, float8)
+ RETURNS geography
+ AS 'MODULE_PATHNAME','geography_expand'
+ LANGUAGE 'C' IMMUTABLE STRICT;
+-- Availability: 1.5.0
+CREATE OR REPLACE FUNCTION ST_DWithin(geography, geography, float8)
+ RETURNS boolean
+ AS 'SELECT $1 && _ST_Expand($2,$3) AND $2 && _ST_Expand($1,$3) AND _ST_Distance($1, $2, $3) < $3'
+ LANGUAGE 'SQL' IMMUTABLE;
+
-- ---------- ---------- ---------- ---------- ---------- ---------- ----------
COMMIT;
#include "geography.h" /* For utility functions. */
Datum geography_distance_sphere(PG_FUNCTION_ARGS);
+Datum geography_expand(PG_FUNCTION_ARGS);
/*
-** geography_in(cstring) returns *GSERIALIZED
+** geography_distance_sphere(GSERIALIZED *g1, GSERIALIZED *g2, double tolerance)
+** returns double distance in meters
*/
PG_FUNCTION_INFO_V1(geography_distance_sphere);
Datum geography_distance_sphere(PG_FUNCTION_ARGS)
PG_RETURN_NULL();
}
+ /* Currently normalizing with a fixed WGS84 radius, in future this
+ should be the average radius of the SRID in play */
distance = distance * WGS84_RADIUS;
/* Clean up, but not all the way to the point arrays */
}
+
+/*
+** geography_expand(GSERIALIZED *g) returns *GSERIALIZED
+**
+** warning, this tricky little function does not expand the
+** geometry at all, just re-writes bounding box value to be
+** a bit bigger. only useful when passing the result along to
+** an index operator (&&)
+*/
+PG_FUNCTION_INFO_V1(geography_expand);
+Datum geography_expand(PG_FUNCTION_ARGS)
+{
+ GIDX *gidx = gidx_new(3);
+ GSERIALIZED *g = NULL;
+ GSERIALIZED *g_out = NULL;
+ double distance;
+ float fdistance;
+ int i;
+
+ /* Get our bounding box out of the geography */
+ geography_datum_gidx(PG_GETARG_DATUM(0), gidx);
+
+ /* Get a pointer to the geography */
+ g = (GSERIALIZED*)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+
+ /* Read our distance value and normalize to unit-sphere. */
+ distance = PG_GETARG_FLOAT8(1) / WGS84_RADIUS;
+ fdistance = (float)distance;
+
+ for( i = 0; i < 3; i++ )
+ {
+ GIDX_SET_MIN(gidx, i, GIDX_GET_MIN(gidx, i) - fdistance);
+ GIDX_SET_MAX(gidx, i, GIDX_GET_MAX(gidx, i) + fdistance);
+ }
+
+ g_out = gidx_insert_into_gserialized(g, gidx);
+ pfree(gidx);
+
+ if( g_out == NULL )
+ PG_RETURN_NULL();
+
+ PG_RETURN_POINTER(g_out);
+
+}
+
return G_SUCCESS;
}
-static GIDX* gidx_from_gbox(GBOX box)
+GIDX* gidx_from_gbox(GBOX box)
{
int ndims;
GIDX *a;
gbox->zmax = (double)GIDX_GET_MAX(a,2);
}
+/*
+** Make a copy of a GSERIALIZED, with a new bounding box value embedded.
+*/
+GSERIALIZED* gidx_insert_into_gserialized(GSERIALIZED *g, GIDX *gidx)
+{
+ int g_ndims = (FLAGS_GET_GEODETIC(g->flags) ? 3 : FLAGS_NDIMS(g->flags));
+ int box_ndims = GIDX_NDIMS(gidx);
+ GSERIALIZED *g_out = NULL;
+ size_t box_size = 2 * g_ndims * sizeof(float);
+
+ /* The dimensionality of the inputs has to match or we are SOL. */
+ if( g_ndims != box_ndims )
+ {
+ return NULL;
+ }
+
+ /* Serialized already has room for a box. We just need to copy it and
+ write the new values into place. */
+ if ( FLAGS_GET_BBOX(g->flags) )
+ {
+ g_out = palloc(VARSIZE(g));
+ memcpy(g_out, g, VARSIZE(g));
+ }
+ /* Serialized has no box. We need to allocate enough space for the old
+ data plus the box, and leave a gap in the memory segment to write
+ the new values into.
+ */
+ else
+ {
+ size_t varsize_new = VARSIZE(g) + box_size;
+ uchar *ptr;
+ g_out = palloc(varsize_new);
+ /* Copy the head of g into place */
+ memcpy(g_out, g, 8);
+ /* Copy the body of g into place after leaving space for the box */
+ ptr = g_out->data;
+ ptr += box_size;
+ memcpy(ptr, g->data, VARSIZE(g) - 8);
+ g_out->flags = FLAGS_SET_BBOX(g_out->flags, 1);
+ SET_VARSIZE(g_out, varsize_new);
+ }
+
+ /* Now write the gidx values into the memory segement */
+ memcpy(g_out->data, gidx->c, box_size);
+
+ return g_out;
+}
+
/*
** Overlapping GIDX box test.
}
/*
-** geography_as_text(*GSERIALIZED) returns cstring
+** geography_as_text(*GSERIALIZED) returns text
*/
PG_FUNCTION_INFO_V1(geography_as_text);
Datum geography_as_text(PG_FUNCTION_ARGS)
/*
-** geography_as_gml(*GSERIALIZED) returns cstring
+** geography_as_gml(*GSERIALIZED) returns text
*/
PG_FUNCTION_INFO_V1(geography_as_gml);
Datum geography_as_gml(PG_FUNCTION_ARGS)
/*
-** geography_as_kml(*GSERIALIZED) returns cstring
+** geography_as_kml(*GSERIALIZED) returns text
*/
PG_FUNCTION_INFO_V1(geography_as_kml);
Datum geography_as_kml(PG_FUNCTION_ARGS)
/*
-** geography_as_svg(*GSERIALIZED) returns cstring
+** geography_as_svg(*GSERIALIZED) returns text
*/
PG_FUNCTION_INFO_V1(geography_as_svg);
Datum geography_as_svg(PG_FUNCTION_ARGS)
/*
-** geography_as_geojson(*GSERIALIZED) returns cstring
+** geography_as_geojson(*GSERIALIZED) returns text
*/
PG_FUNCTION_INFO_V1(geography_as_geojson);
Datum geography_as_geojson(PG_FUNCTION_ARGS)
}
/*
-** geography_as_binary(*GSERIALIZED) returns *char
+** geography_as_binary(*GSERIALIZED) returns bytea
*/
PG_FUNCTION_INFO_V1(geography_as_binary);
Datum geography_as_binary(PG_FUNCTION_ARGS)
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