PK_ERROR_code_t         PK_FACE_sweep
(
--- received arguments ---
int                     n_faces,       --- number of faces
const PK_FACE_t         faces[],       --- faces
PK_VECTOR_t             path,          --- translation vector
PK_LOGICAL_t            local_check,   --- whether local checking will be done

--- returned arguments ---
int              *const n_laterals,    --- number of laterals
PK_FACE_t       **const laterals,      --- new faces (may be NULL)
PK_EDGE_t       **const bases,         --- edges swept into laterals
                                       --- (may be NULL)
PK_local_check_t *const check_result   --- result of local check
)


This function sweeps one or more faces of a solid body.


Specific Errors:
    PK_ERROR_unsuitable_entity     Face(s) unsuitable for sweep
    PK_ERROR_wrong_entity          Bad arguments
    PK_ERROR_non_manifold          Can't sweep face with non-manifold boundary
    PK_ERROR_impossible_sweep      Can't determine swept geometry
    PK_ERROR_su_self_intersect     Sweep would produce a self intersecting surf


The entities to be swept are moved along the path vector leaving lateral
entities in their wake. Entities which may be swept, the laterals they produce
and the type of the resulting body are identified in the following table.

    Swept Entities        |    Laterals Returned     |      Result
===========================================================================
                          |                          |
One or more faces of a    |   One or more faces      |     Solid body
solid body                |                          |
===========================================================================

For every entry in laterals, there is a corresponding entry in bases. This
array contains the topological entities extruded to create the lateral
entities.
For every lateral face there is a swept edge from the original body and for
every lateral edge there is a swept vertex.

 Suitable Sweep Entities:

   . Any group of manifold faces of a solid body. Entire shells must
     not be contained within the list.

Attempting to sweep an entity which is not one of the above will give rise
to the error PK_ERROR_unsuitable_entity.

A face which has an edge whose attached curve is of the class PK_CLASS_icurve,
(ie intersection curve), PK_CLASS_fcurve (ie foreign geometry),
PK_CLASS_spcurve (ie sp-curve) or class PK_CLASS_cpcurve (ie constant parameter
curve) cannot be swept.

After a sweep any coincident topology will not be fused or united.

In general this procedure may give rise to self-intersecting body
boundaries, which could cause unpredictable errors later.

Any new surfaces created are analytic surfaces if possible. If it is
not possible to use an analytic surface then the class of the new
surface will be PK_CLASS_swept or PK_CLASS_bsurf depending upon the most
recent call to PK_SESSION_set_swept_spun_surfs

If local checking is switched on (local_check = PK_LOGICAL_true), consistency
checks will be made on newly created topological and geometrical
entities, and the result of the check returned.
A result of PK_local_check_ok_c indicates the body is valid. A result
of PK_local_check_negated_c indicates that the result body was originally
"inside out" but has been negated, and is now "positive" (has positive volume)
and valid. A result of PK_local_check_failed_c indicates the body
is self-intersecting and further modelling operations on it may fail.

If local_check is PK_LOGICAL_false, local checking will be switched off and
the result returned will be PK_local_check_no_c.

A self-intersecting body can be returned.