union_intersecting_pairs()

int union_intersecting_pairs	(	GEOSGeometry **	geoms,
		uint32_t	num_geoms,
		UNIONFIND *	uf
	)

Definition at line 158 of file lwgeom_geos_cluster.c.

{
        uint32_t p, i;
        struct STRTree tree;
        struct QueryContext cxt =
        {
                .items_found = NULL,
                .num_items_found = 0,
                .items_found_size = 0
        };
        int success = LW_SUCCESS;
 
        if (num_geoms <= 1)
                return LW_SUCCESS;
 
        tree = make_strtree((void**) geoms, num_geoms, LW_FALSE);
        if (tree.tree == NULL)
        {
                destroy_strtree(&tree);
                return LW_FAILURE;
        }
 
        for (p = 0; p < num_geoms; p++)
        {
                const GEOSPreparedGeometry* prep = NULL;
 
                if (!geoms[p] || GEOSisEmpty(geoms[p]))
                        continue;
 
                cxt.num_items_found = 0;
                GEOSSTRtree_query(tree.tree, geoms[p], &query_accumulate, &cxt);
 
                for (i = 0; i < cxt.num_items_found; i++)
                {
                        uint32_t q = *((uint32_t*) cxt.items_found[i]);
 
                        if (p != q && UF_find(uf, p) != UF_find(uf, q))
                        {
                                int geos_type = GEOSGeomTypeId(geoms[p]);
                                int geos_result;
 
                                /* Don't build prepared a geometry around a Point or MultiPoint -
                                 * there are some problems in the implementation, and it's not clear
                                 * there would be a performance benefit in any case.  (See #3433)
                                 */
                                if (geos_type != GEOS_POINT && geos_type != GEOS_MULTIPOINT)
                                {
                                        /* Lazy initialize prepared geometry */
                                        if (prep == NULL)
                                        {
                                                prep = GEOSPrepare(geoms[p]);
                                        }
                                        geos_result = GEOSPreparedIntersects(prep, geoms[q]);
                                }
                                else
                                {
                                        geos_result = GEOSIntersects(geoms[p], geoms[q]);
                                }
                                if (geos_result > 1)
                                {
                                        success = LW_FAILURE;
                                        break;
                                }
                                else if (geos_result)
                                {
                                        UF_union(uf, p, q);
                                }
                        }
                }
 
                if (prep)
                        GEOSPreparedGeom_destroy(prep);
 
                if (!success)
                        break;
        }
 
        if (cxt.items_found)
                lwfree(cxt.items_found);
 
        destroy_strtree(&tree);
        return success;
}

References destroy_strtree(), QueryContext::items_found, LW_FAILURE, LW_FALSE, LW_SUCCESS, lwfree(), make_strtree(), QueryContext::num_items_found, query_accumulate(), STRTree::tree, UF_find(), and UF_union().

Referenced by cluster_intersecting(), and ST_ClusterIntersectingWin().

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