Creating NURBs Curve with cull "points"?

Hello All.

A total beginner here, so i ask for some understanding if i ask a very basic question...

I need to draw a 4 degree NURBS curve, using only "points" that were created by Grasshopper. As i understand, they are called culls. I just can find a way how to use my 4 cull points... Please help.

The thumbnail for NURBS curve wants to have a Vertices input as a list!

Do i need to create a list out of my 4 cull points? How do i create such a list?

Thank you in advance!

Replies to This Discussion

Permalink Reply by Kristijan on October 13, 2016 at 8:27am

P.S.

The problem is not so easy as it sounds.

To create a NURBS curve using only cull points, works well if they are created all in one step.

But i have 2 outer cull points, that are created on a curve and 2 inner cull points, that are created on a line, which was created with the help of the two outer points, mentioned at the beginning.

So there are 2 more steps/thumbnails between the creation of the outer 2 points, and the inner 2 points and now, when i want to use these 4 points to make a simple NURBS curve, it just does not generate it...

Permalink Reply by Kristijan on October 14, 2016 at 1:27am

Hello Tom.

Thank you for your prompt answer.

I made a mistake while describing the problem... late hours...

I want to create a nurbs curve with 4 points, which is of course 3rd degree. That is clear.

However, i have attached my setup which shows exactly, what i have done to get my 4 points but i just cant get them to generate the desired NURBS Curve, which is at the end of the tree, called NURBS S2.

The final goal of my setup is to make a sweep 2, using top and bottom rails, and using 3 sections, where the first and last are only lines, but the section S2 is a nurbs curve, which can be moved and manipulated as desired.

If you will open the attached file, you will see that nurbs s2 doesnt work...

Attachments:

GRASSHOPPER-TEST.gh, 9 KB

Permalink Reply by Kristijan on October 14, 2016 at 3:02am

P.S.

I have found the problem and the solution.

In the described case, i have probably created a definiton loop, by using 2 points for creation of new related 2 points, and then trying to use all 4 of them simultaneously to create the nurbs curve.

I have solved this by simply creating 2 lines and using these 2 lines to create 4 new end points, forcing GH to recalculate, and then the NURBS curve used these new but identical points, to make my so much desired curve.

Thank you!

With best regards.

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