char *msudf_lineMerge(UDF_INIT *initid,UDF_ARGS *args, char *buf,
unsigned long *length, char *is_null, char *error)
{
char *result;
GEOSGeom geom1,geom2;
DEBUG("msudf_lineMerge");
geom1 = msudf_getGeometry((unsigned char *)args->args[0],args->lengths[0]);
if (geom1 == NULL) {
strcpy(error,"Invalid geometry.");
*is_null = 1;
return NULL;
}
geom2 = GEOSLineMerge(geom1);
if (geom2 != NULL) {
GEOSSetSRID(geom2,GEOSGetSRID(geom1));
result = msudf_returnGeometry(initid,length,geom2);
GEOSGeom_destroy(geom1);
GEOSGeom_destroy(geom2);
return result;
} else {
GEOSGeom_destroy(geom1);
*is_null = 1;
return NULL;
}
}
LWGEOM*
lwgeom_node(const LWGEOM* lwgeom_in)
{
#if POSTGIS_GEOS_VERSION < 33
lwerror("The GEOS version this postgis binary "
"was compiled against (%d) doesn't support "
"'GEOSUnaryUnion' function (3.3.0+ required)",
POSTGIS_GEOS_VERSION);
return NULL;
#else /* POSTGIS_GEOS_VERSION >= 33 */
GEOSGeometry *g1, *gu, *gm;
LWGEOM *ep, *lines;
LWCOLLECTION *col, *tc;
int pn, ln, np, nl;
if ( lwgeom_dimension(lwgeom_in) != 1 ) {
lwerror("Noding geometries of dimension != 1 is unsupported");
return NULL;
}
initGEOS(lwgeom_geos_error, lwgeom_geos_error);
g1 = LWGEOM2GEOS(lwgeom_in);
if ( ! g1 ) {
lwerror("LWGEOM2GEOS: %s", lwgeom_geos_errmsg);
return NULL;
}
ep = lwgeom_extract_unique_endpoints(lwgeom_in);
if ( ! ep ) {
GEOSGeom_destroy(g1);
lwerror("Error extracting unique endpoints from input");
return NULL;
}
/* Unary union input to fully node */
gu = GEOSUnaryUnion(g1);
GEOSGeom_destroy(g1);
if ( ! gu ) {
lwgeom_free(ep);
lwerror("GEOSUnaryUnion: %s", lwgeom_geos_errmsg);
return NULL;
}
/* Linemerge (in case of overlaps) */
gm = GEOSLineMerge(gu);
GEOSGeom_destroy(gu);
if ( ! gm ) {
lwgeom_free(ep);
lwerror("GEOSLineMerge: %s", lwgeom_geos_errmsg);
return NULL;
}
lines = GEOS2LWGEOM(gm, FLAGS_GET_Z(lwgeom_in->flags));
GEOSGeom_destroy(gm);
if ( ! lines ) {
lwgeom_free(ep);
lwerror("Error during GEOS2LWGEOM");
return NULL;
}
/*
* Reintroduce endpoints from input, using split-line-by-point.
* Note that by now we can be sure that each point splits at
* most _one_ segment as any point shared by multiple segments
* would already be a node. Also we can be sure that any of
* the segments endpoints won't split any other segment.
* We can use the above 2 assertions to early exit the loop.
*/
col = lwcollection_construct_empty(MULTILINETYPE, lwgeom_in->srid,
FLAGS_GET_Z(lwgeom_in->flags),
FLAGS_GET_M(lwgeom_in->flags));
np = lwgeom_ngeoms(ep);
for (pn=0; pn<np; ++pn) { /* for each point */
const LWPOINT* p = (LWPOINT*)lwgeom_subgeom(ep, pn);
nl = lwgeom_ngeoms(lines);
for (ln=0; ln<nl; ++ln) { /* for each line */
const LWLINE* l = (LWLINE*)lwgeom_subgeom(lines, ln);
int s = lwline_split_by_point_to(l, p, (LWMLINE*)col);
if ( ! s ) continue; /* not on this line */
if ( s == 1 ) {
/* found on this line, but not splitting it */
break;
}
/* splits this line */
/* replace this line with the two splits */
if ( lwgeom_is_collection(lines) ) {
tc = (LWCOLLECTION*)lines;
lwcollection_reserve(tc, nl + 1);
while (nl > ln+1) {
tc->geoms[nl] = tc->geoms[nl-1];
--nl;
}
lwgeom_free(tc->geoms[ln]);
tc->geoms[ln] = col->geoms[0];
tc->geoms[ln+1] = col->geoms[1];
tc->ngeoms++;
} else {
lwgeom_free(lines);
/* transfer ownership rather than cloning */
lines = (LWGEOM*)lwcollection_clone_deep(col);
assert(col->ngeoms == 2);
lwgeom_free(col->geoms[0]);
lwgeom_free(col->geoms[1]);
}
/* reset the vector */
assert(col->ngeoms == 2);
col->ngeoms = 0;
break;
}
}
lwgeom_free(ep);
lwcollection_free(col);
lines->srid = lwgeom_in->srid;
return (LWGEOM*)lines;
#endif /* POSTGIS_GEOS_VERSION >= 33 */
}
