BSpline/Nurbs Derivatives w.r.t poles

Hi all,

First time on this forum, so please be gentle.

Here's my problem. I load in a STEP model and I want to be able to evaluate derivatives on edges/surfaces of the geometry with respect to the B-spline or NURBS control points/poles. Is this possible?

I've looked through the BSpline class reference, and I know that it can evaluate derivatives at s or uv parameters, but that's not what I'm looking for. I would like the derivative of the xyz location at any given point on the curve/surface with respect to the control point/pole location.

Is there any such feature?

Thank you for your time,


Pawel's picture

Dear John,

I'm not a mathematician and so I'm not sure what you mean by "Nurbs Derivatives w.r.t poles".

Would that be a solution for you to project the control point onto the curve/surface, get the parameter(s) at that point and compute the derivative (w.r.t parameter)?

Hope this helps