ST_MinimumBoundingCircle()

Datum ST_MinimumBoundingCircle

(

PG_FUNCTION_ARGS

)

Definition at line 1177 of file lwgeom_functions_analytic.c.

{
        GSERIALIZED* geom;
        LWGEOM* input;
        LWBOUNDINGCIRCLE* mbc = NULL;
        LWGEOM* lwcircle;
        GSERIALIZED* center;
        int segs_per_quarter;
 
        if (PG_ARGISNULL(0))
                PG_RETURN_NULL();
 
        geom = PG_GETARG_GSERIALIZED_P(0);
        segs_per_quarter = PG_GETARG_INT32(1);
 
        /* Empty geometry? Return POINT EMPTY */
        if (gserialized_is_empty(geom))
        {
                lwcircle = (LWGEOM*) lwpoint_construct_empty(gserialized_get_srid(geom), LW_FALSE, LW_FALSE);
        }
        else
        {
                input = lwgeom_from_gserialized(geom);
                mbc = lwgeom_calculate_mbc(input);
 
                if (!(mbc && mbc->center))
                {
                        lwpgerror("Error calculating minimum bounding circle.");
                        lwgeom_free(input);
                        PG_RETURN_NULL();
                }
 
                /* Zero radius? Return a point. */
                if (mbc->radius == 0)
                        lwcircle = lwpoint_as_lwgeom(lwpoint_make2d(input->srid, mbc->center->x, mbc->center->y));
                else
                        lwcircle = lwpoly_as_lwgeom(lwpoly_construct_circle(input->srid, mbc->center->x, mbc->center->y, mbc->radius, segs_per_quarter, LW_TRUE));
 
                lwboundingcircle_destroy(mbc);
                lwgeom_free(input);
        }
 
        center = geometry_serialize(lwcircle);
        lwgeom_free(lwcircle);
 
        PG_RETURN_POINTER(center);
}

References LWBOUNDINGCIRCLE::center, gserialized_get_srid(), gserialized_is_empty(), LW_FALSE, LW_TRUE, lwboundingcircle_destroy(), lwgeom_calculate_mbc(), lwgeom_free(), lwgeom_from_gserialized(), lwpoint_as_lwgeom(), lwpoint_construct_empty(), lwpoint_make2d(), lwpoly_as_lwgeom(), lwpoly_construct_circle(), LWBOUNDINGCIRCLE::radius, LWGEOM::srid, POINT2D::x, and POINT2D::y.

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