lwgeom_extract_geometry_n()

static LWGEOM * lwgeom_extract_geometry_n ( LWGEOM *  lwgeom, int32  idx, bool  patches_as_geometries  )

static

Definition at line 320 of file lwgeom_ogc.c.

{
        LWCOLLECTION *coll = NULL;
        LWGEOM *subgeom = NULL;
 
        /* Empty returns NULL */
        if (lwgeom_is_empty(lwgeom))
                return NULL;
 
        /* Unitary geometries */
        if (lwgeom_is_unitary(lwgeom))
        {
                /* If it's a TIN or PolyhedralSurface and we want to access patches */
                if (lwgeom_has_patches(lwgeom) && patches_as_geometries)
                {
                        coll = lwgeom_as_lwcollection(lwgeom);
                        if (!coll)
                        {
                                /* Single patch case */
                                if (idx == 1)
                                        return lwgeom;
                                else
                                        return NULL;
                        }
                }
                else
                {
                        /* Standard unitary geometry handling */
                        if (idx == 1)
                                return lwgeom;
                        else
                                return NULL;
                }
        }
        else
        {
                coll = lwgeom_as_lwcollection(lwgeom);
        }
 
        if (!coll)
                return NULL;
 
        /* Handle out-of-range index value */
        idx -= 1;
        if (idx < 0 || idx >= (int32) coll->ngeoms)
                return NULL;
 
        subgeom = coll->geoms[idx];
        return subgeom;
}

References LWCOLLECTION::geoms, lwgeom_as_lwcollection(), lwgeom_has_patches(), lwgeom_is_empty(), lwgeom_is_unitary(), and LWCOLLECTION::ngeoms.

Referenced by LWGEOM_geometryn_collection(), and LWGEOM_patchn().

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