"List" and "InsertKnot" in Grasshopper

I am starting a project an would like to know if there are any commands in grasshopper that are similar to the Rhino 5 commands of "list" and "InsertKnot". I need to read the knots for a curve and then insert more knots. I have searched through the forms and Google and have not found anything, hence why I am posting. Any direction would be greatly appreciated. Thanks!

Replies to This Discussion

Permalink Reply by David Rutten on July 25, 2014 at 11:59am

You can get all the information from a nurbs curve, including the knot vector, but there are no components for inserting knots, or inserting kinks, or inserting control-points. It can be done relatively easily using a scripted component.

The question that remains is how do you want to define where you want these knots inserted?

David Rutten

david@mcneel.com

Permalink Reply by Alexis Moreno on July 25, 2014 at 12:07pm

I would like to insert the knots relative to a different curve.

e.g.

I will have two curves with lengths of A and B. Curve A would have knots on the %25^th and %66^th of the total length. Curve B will have a knot on the %50^th of the total length of the curve. I would then like it for both curves to have knots on the %25^th, %50^th, and %66^th of the total length. I want this for lofting purposes of course.

Permalink Reply by David Rutten on July 25, 2014 at 1:23pm

That can certainly be done. I assume you may in fact have a list of curves, rather than just 2? Are lengths measured in curve parameter space or in world space? Should there be a tolerance rejection? I.e. what if curve A has a knot at 55.6% and curve B has a knot at 55.7%, do you still want to add a knot to each one?

David Rutten

david@mcneel.com

Permalink Reply by Alexis Moreno on July 25, 2014 at 2:25pm

We do have a list of curves that we are trying to work with. The curves we're working with exist in a curve parameter space.

In the example you provided we would add knots to both curves.

Thanks,

Alexis

Permalink Reply by David Rutten on July 26, 2014 at 2:45am

As I understand Rhino already inserts those knots during Loft, but perhaps you're dealing with corner cases where it doesn't...

I attached a GH file with a C# script that makes sure all curves in a list have the same knot topology*.

David Rutten

david@mcneel.com