mvt_iterate_clip_by_box_geos()

static LWGEOM* mvt_iterate_clip_by_box_geos ( LWGEOM *  lwgeom, GBOX *  clip_gbox, uint8_t  basic_type  )

static

Clips the geometry using GEOSIntersection in a "safe way", cleaning the input if necessary and clipping MULTIPOLYGONs separately to reduce the impact of using invalid input in GEOS Might return NULL.

Definition at line 926 of file mvt.c.

{
        if (basic_type != POLYGONTYPE)
        {
                return mvt_unsafe_clip_by_box(lwgeom, clip_gbox);
        }
 
        if (lwgeom->type != MULTIPOLYGONTYPE || ((LWMPOLY *)lwgeom)->ngeoms == 1)
        {
                return mvt_safe_clip_polygon_by_box(lwgeom, clip_gbox);
        }
        else
        {
                GBOX geom_box;
                uint32_t i;
                LWCOLLECTION *lwmg;
                LWCOLLECTION *res;
 
                gbox_init(&geom_box);
                FLAGS_SET_GEODETIC(geom_box.flags, 0);
                lwgeom_calculate_gbox(lwgeom, &geom_box);
 
                lwmg = ((LWCOLLECTION *)lwgeom);
                res = lwcollection_construct_empty(
                    MULTIPOLYGONTYPE, lwgeom->srid, FLAGS_GET_Z(lwgeom->flags), FLAGS_GET_M(lwgeom->flags));
                for (i = 0; i < lwmg->ngeoms; i++)
                {
                        LWGEOM *clipped = mvt_safe_clip_polygon_by_box(lwcollection_getsubgeom(lwmg, i), clip_gbox);
                        if (clipped)
                        {
                                clipped = lwgeom_to_basic_type(clipped, POLYGONTYPE);
                                if (!lwgeom_is_empty(clipped) &&
                                    (clipped->type == POLYGONTYPE || clipped->type == MULTIPOLYGONTYPE))
                                {
                                        if (!lwgeom_is_collection(clipped))
                                        {
                                                lwcollection_add_lwgeom(res, clipped);
                                        }
                                        else
                                        {
                                                uint32_t j;
                                                for (j = 0; j < ((LWCOLLECTION *)clipped)->ngeoms; j++)
                                                        lwcollection_add_lwgeom(
                                                            res, lwcollection_getsubgeom((LWCOLLECTION *)clipped, j));
                                        }
                                }
                        }
                }
                return lwcollection_as_lwgeom(res);
        }
}

References GBOX::flags, LWGEOM::flags, FLAGS_GET_M, FLAGS_GET_Z, FLAGS_SET_GEODETIC, gbox_init(), lwcollection_add_lwgeom(), lwcollection_as_lwgeom(), lwcollection_construct_empty(), lwcollection_getsubgeom(), lwgeom_calculate_gbox(), lwgeom_is_collection(), lwgeom_is_empty(), lwgeom_to_basic_type(), MULTIPOLYGONTYPE, mvt_safe_clip_polygon_by_box(), mvt_unsafe_clip_by_box(), LWCOLLECTION::ngeoms, POLYGONTYPE, window::res, LWGEOM::srid, and LWGEOM::type.

Referenced by mvt_clip_and_validate_geos().

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