PK_ERROR_code_t PK_BCURVE_add_knot
(
--- received arguments ---
PK_BCURVE_t     bcurve,      --- bcurve
double          t            --- split parameter
)


This function modifies the given bcurve by inserting a knot at the given
split parameter.


Specific Errors:
    PK_ERROR_is_attached            bcurve is attached to geometry
    PK_ERROR_bad_parameter          parameter out of range
    PK_ERROR_bad_knots              maximum multiplicity of knots


This function modifies a B-curve by inserting a knot, resulting in
the addition of a (possibly null) segment.
The shape of the B-curve is not changed.

The parameter t at which the new knot is to be inserted must be within the
range as given by PK_CURVE_ask_param.

The new knot must not increase the multiplicity of any existing knot to more
than the order for an end knot, or order-1 for an internal knot.

If t lies within a segment then a new segment will be added to the curve.

If 't' lies on a segment boundary then the segment, added will be null.
Adding a null segment to a curve only
affects the B-spline representation (it duplicates a knot).


A B-curve cannot be modified if it is attached to an edge or face.