BOX3D_to_LWGEOM()

Datum BOX3D_to_LWGEOM

(

PG_FUNCTION_ARGS

)

Alter BOX3D cast so that a valid geometry is always returned depending upon the size of the BOX3D. The code makes the following assumptions:

• If the BOX3D is a single point then return a POINT geometry
• If the BOX3D represents a line in any of X, Y or Z dimension, return a LINESTRING geometry
• If the BOX3D represents a plane in the X, Y, or Z dimension, return a POLYGON geometry
• Otherwise return a POLYHEDRALSURFACE geometry

Definition at line 191 of file lwgeom_box3d.c.

{
        BOX3D *box = (BOX3D *)PG_GETARG_POINTER(0);
        POINTARRAY *pa;
        GSERIALIZED *result;
        POINT4D pt;
 
        pa = ptarray_construct_empty(LW_TRUE, LW_FALSE, 5);
 
        /* BOX3D is a point */
        if ((box->xmin == box->xmax) && (box->ymin == box->ymax) && (box->zmin == box->zmax))
        {
                LWPOINT *lwpt = lwpoint_construct(SRID_UNKNOWN, NULL, pa);
 
                pt.x = box->xmin;
                pt.y = box->ymin;
                pt.z = box->zmin;
                ptarray_append_point(pa, &pt, LW_TRUE);
 
                result = geometry_serialize(lwpoint_as_lwgeom(lwpt));
                lwpoint_free(lwpt);
        }
        /* BOX3D is a line */
        else if (((box->xmin == box->xmax || box->ymin == box->ymax) && box->zmin == box->zmax) ||
                 ((box->xmin == box->xmax || box->zmin == box->zmax) && box->ymin == box->ymax) ||
                 ((box->ymin == box->ymax || box->zmin == box->zmax) && box->xmin == box->xmax))
        {
                LWLINE *lwline = lwline_construct(SRID_UNKNOWN, NULL, pa);
 
                pt.x = box->xmin;
                pt.y = box->ymin;
                pt.z = box->zmin;
                ptarray_append_point(pa, &pt, LW_TRUE);
                pt.x = box->xmax;
                pt.y = box->ymax;
                pt.z = box->zmax;
                ptarray_append_point(pa, &pt, LW_TRUE);
 
                result = geometry_serialize(lwline_as_lwgeom(lwline));
                lwline_free(lwline);
        }
        /* BOX3D is a polygon in the X plane */
        else if (box->xmin == box->xmax)
        {
                POINT4D points[4];
                LWPOLY *lwpoly;
 
                /* Initialize the 4 vertices of the polygon */
                points[0] = (POINT4D){box->xmin, box->ymin, box->zmin, 0.0};
                points[1] = (POINT4D){box->xmin, box->ymax, box->zmin, 0.0};
                points[2] = (POINT4D){box->xmin, box->ymax, box->zmax, 0.0};
                points[3] = (POINT4D){box->xmin, box->ymin, box->zmax, 0.0};
 
                lwpoly = lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[0], &points[1], &points[2], &points[3]);
                result = geometry_serialize(lwpoly_as_lwgeom(lwpoly));
                lwpoly_free(lwpoly);
        }
        /* BOX3D is a polygon in the Y plane */
        else if (box->ymin == box->ymax)
        {
                POINT4D points[4];
                LWPOLY *lwpoly;
 
                /* Initialize the 4 vertices of the polygon */
                points[0] = (POINT4D){box->xmin, box->ymin, box->zmin, 0.0};
                points[1] = (POINT4D){box->xmax, box->ymin, box->zmin, 0.0};
                points[2] = (POINT4D){box->xmax, box->ymin, box->zmax, 0.0};
                points[3] = (POINT4D){box->xmin, box->ymin, box->zmax, 0.0};
 
                lwpoly = lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[0], &points[1], &points[2], &points[3]);
                result = geometry_serialize(lwpoly_as_lwgeom(lwpoly));
                lwpoly_free(lwpoly);
        }
        /* BOX3D is a polygon in the Z plane */
        else if (box->zmin == box->zmax)
        {
                POINT4D points[4];
                LWPOLY *lwpoly;
 
                /* Initialize the 4 vertices of the polygon */
                points[0] = (POINT4D){box->xmin, box->ymin, box->zmin, 0.0};
                points[1] = (POINT4D){box->xmin, box->ymax, box->zmin, 0.0};
                points[2] = (POINT4D){box->xmax, box->ymax, box->zmin, 0.0};
                points[3] = (POINT4D){box->xmax, box->ymin, box->zmin, 0.0};
 
                lwpoly = lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[0], &points[1], &points[2], &points[3]);
                result = geometry_serialize(lwpoly_as_lwgeom(lwpoly));
                lwpoly_free(lwpoly);
        }
        /* BOX3D is a polyhedron */
        else
        {
                POINT4D points[8];
                static const int ngeoms = 6;
                LWGEOM **geoms = (LWGEOM **)lwalloc(sizeof(LWGEOM *) * ngeoms);
                LWGEOM *geom = NULL;
 
                /* Initialize the 8 vertices of the box */
                points[0] = (POINT4D){box->xmin, box->ymin, box->zmin, 0.0};
                points[1] = (POINT4D){box->xmin, box->ymax, box->zmin, 0.0};
                points[2] = (POINT4D){box->xmax, box->ymax, box->zmin, 0.0};
                points[3] = (POINT4D){box->xmax, box->ymin, box->zmin, 0.0};
                points[4] = (POINT4D){box->xmin, box->ymin, box->zmax, 0.0};
                points[5] = (POINT4D){box->xmin, box->ymax, box->zmax, 0.0};
                points[6] = (POINT4D){box->xmax, box->ymax, box->zmax, 0.0};
                points[7] = (POINT4D){box->xmax, box->ymin, box->zmax, 0.0};
 
                /* add bottom polygon */
                geoms[0] = lwpoly_as_lwgeom(
                    lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[0], &points[1], &points[2], &points[3]));
                /* add top polygon */
                geoms[1] = lwpoly_as_lwgeom(
                    lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[4], &points[7], &points[6], &points[5]));
                /* add left polygon */
                geoms[2] = lwpoly_as_lwgeom(
                    lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[0], &points[4], &points[5], &points[1]));
                /* add right polygon */
                geoms[3] = lwpoly_as_lwgeom(
                    lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[3], &points[2], &points[6], &points[7]));
                /* add front polygon */
                geoms[4] = lwpoly_as_lwgeom(
                    lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[0], &points[3], &points[7], &points[4]));
                /* add back polygon */
                geoms[5] = lwpoly_as_lwgeom(
                    lwpoly_construct_rectangle(LW_TRUE, LW_FALSE, &points[1], &points[5], &points[6], &points[2]));
 
                geom = (LWGEOM *)lwcollection_construct(POLYHEDRALSURFACETYPE, SRID_UNKNOWN, NULL, ngeoms, geoms);
 
                FLAGS_SET_SOLID(geom->flags, 1);
 
                result = geometry_serialize(geom);
                lwcollection_free((LWCOLLECTION *)geom);
        }
 
        gserialized_set_srid(result, box->srid);
 
        PG_RETURN_POINTER(result);
}

References LWGEOM::flags, FLAGS_SET_SOLID, gserialized_set_srid(), LW_FALSE, LW_TRUE, lwalloc(), lwcollection_construct(), lwcollection_free(), lwline_as_lwgeom(), lwline_construct(), lwline_free(), lwpoint_as_lwgeom(), lwpoint_construct(), lwpoint_free(), lwpoly_as_lwgeom(), lwpoly_construct_rectangle(), lwpoly_free(), POLYHEDRALSURFACETYPE, ptarray_append_point(), ptarray_construct_empty(), result, BOX3D::srid, SRID_UNKNOWN, POINT4D::x, BOX3D::xmax, BOX3D::xmin, POINT4D::y, BOX3D::ymax, BOX3D::ymin, POINT4D::z, BOX3D::zmax, and BOX3D::zmin.

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