algorithmic modeling for Rhino

The darling of the Grasshopper community mentioned a GH & Coffee challenge so I have decided to do exactly that:

Original post if you're interested:

Here's the challenge:

I've based it on my recent attempts to learn GH by repeating problems posted on the forum. I find most of the solutions aren't really parametric and only work under one set of conditions which really defeats the purpose and this forms part of the challenge. Solve this post:

Summary of problem:

1. A set of lines with a constrained length in static positions around a variable radii circular base

2. The top circle constrains the end point of the lines and can rotate and also change its radii, thus 'pulling' the line end points in its direction(s)

3. The top will therefore 'sink' as the rotation occurs or either radii change due to the mechanics of the constraints




1. Must work parametrically, i.e. not break when inputs change

2. 1 Hour to solve it

3. Use as few components as possible (clustering is cheating!)

4. Scripting not allowed

5. Must solve as efficiently as possible

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Replies to This Discussion

Attached is my solution.

Criteria assessment:

1. Check

2. 46 min

3. Check

4. Check

5. Check (compared to the other offering in the original post of this problem, which incidentally doesnt really work!)


While not perfect, it most certainly works! Contenders, please enter the ring...

File if you missed it.


Wasn't it you who missed it? :)  

Have patience.

I've never been called the darling of the GH community before. Thanks!

I think it was about time....

I'm going to go and have a sandwich now in accordance with professor internet's level 1 rule in life. :)

I think you deserve a celebratory sarnie, but dont forget about the challenge...

5 min. with simple grasshopper components



Criteria assessment:

1. Check

2. 5 min

3. Check

4. Check

5. Fail (spheres slows the solver down as the count increases)

15 min...



Criteria assessment:

1. Check

2. 15 min

3. Check

4. Check

5. Check

Here's another approach defining initial height of the structure instead of bar length

15 min to solve + 10 to clean up the solution






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