struct PK_SURF_make_cus_isocline_o_s
    {
    int            o_t_version;   --- version number of option structure
    PK_LOGICAL_t   old_iso;       --- whether former isocline curves are
                                  --- to be produced (PK_LOGICAL_false)
    PK_LOGICAL_t   all_points;    --- whether curves using all the control
                                  --- points are to be made (PK_LOGICAL_true)
    };
typedef struct PK_SURF_make_cus_isocline_o_s PK_SURF_make_cus_isocline_o_t;



Contains optional controls on isocline curve generation.



Description of fields:

'old_iso'                If this flag is set to PK_LOGICAL_true, the
                         former isocline curve behaviour is selected
                         and the returned curves are identical to those
                         produced using PK_SURF_make_curves_isocline.
                         When this flag is set to PK_LOGICAL_false, the
                         default value, the more accurate isocline curves
                         are generated.
                         In the case of analytic isocline curves, this
                         flag as no effect.

'all_points'             In the general case, if this flag is set to
                         PK_LOGICAL_true, the default value, all the
                         control points which can be produced by the
                         isocline calculation are used to generate the
                         curves (NURBS vertices). Otherwise, if this
                         flag is set to PK_LOGICAL_false, only half of
                         them are used.
                         These latter curves are obviously less accurate
                         than those using all the control points, but
                         use less memory storage space.
                         In the case of analytic isocline curves, this
                         flag is irrelevant.