struct PK_blend_shape_s
    {
    PK_blend_xs_plane_t   xsection;   --- cross section plane
                                      --- (PK_blend_xs_rolling_ball_c)
    double                radius;     --- constant radius
                                      --- (0.0)
    PK_CURVE_t            parameter;  --- 3D parameter curve
                                      --- (PK_ENTITY_null)
    PK_LAW_sf_t           range1;     --- 1D law function;
                                      --- ranges off left
    PK_LAW_sf_t           range2;     --- 1D law function;
                                      --- ranges off right
    PK_LAW_sf_t           rho;        --- 1D law function;
                                      --- rhos for general conics
    PK_BCURVE_t           depth;      --- 2D law curve; curvature cts blends
                                      --- (PK_ENTITY_null)
    double                width;      --- width of blend for Constant Width
                                      --- blends (0.0)
    double                ratio;      --- ratio of blend ranges for Constant
                                      --- Width blends (1.0)
    PK_blend_xs_shape_t   xs_shape;   --- cross section shape
                                      --- (PK_blend_xs_shape_unset_c)
    };
typedef struct PK_blend_shape_s PK_blend_shape_t;



This structure defines the shape of a blend.


                        Blend Shape Options:

 xsection   Cross section plane, may be one of:
              PK_blend_xs_rolling_ball_c (default) or
              PK_blend_xs_disc_c or
              PK_blend_xs_isoparameter_c

 radius     Radius of blend for defining a constant radius blend
              (default 0.0). A value of 0.0 will be taken to mean
              that this field is unset.

 parameter  3D parameter curve.

 range1     1D law function; ranges off left.  If this is supplied
              a parameter curve must be provided in parameter.

 range2     1D law function; ranges off right.  If this is supplied
              a parameter curve must be provided in parameter.

 rho        1D law function; rhos for general conics.  If this is supplied
              a parameter curve must be provided in parameter.

 depth      2D law curve for curvature continuous blends.  If this is
              supplied a parameter curve must be provided in parameter.

 width      Width of blend for defining constant width blends (default 0.0).
              A value of 0.0 will be taken to mean that this field is unset.

 ratio      Ratio of blend ranges for constant width blends.  The ratio is
              defined as "ranges off left" / "ranges off right".  The default
              is 1.0 i.e. equal ranges.  This field will be ignored unless the
              width field is set.

 xs_shape   Cross section shape, may be one of:
              PK_blend_xs_shape_unset_c (default)
              PK_blend_xs_shape_conic_c
              PK_blend_xs_shape_g2_c
              PK_blend_xs_shape_chamfer_c

If no radius, width or range functions are defined then the blend will be
assumed to be determined by its constraints, for example tangent-holdline
blends.

If the width field is set to a non-zero value, then xsection must
be set to PK_blend_xs_rolling_ball_c.

When more than one of range1, range2 and rho are set, they must
have equal degree, periodicity, closure and knot set.  The depth
option is incompatible with the rho option.

For further details on the use of these options please refer to the Face-Face
Blending Chapter of the Parasolid Functional Description.