I have a Grasshopper definition that generates vertical lamellas positioned at a 90‑degree angle to an existing surface. I’d like to control each lamella’s angle with a curve, so that the angle deviates from 90 degrees as I edit the curve—for example, the lamella angle would follow the curve’s Y‑value.
Lamellas.gh (13.5 KB)
You didn’t internalize two curves.
You are right, hope it’s the curves are there now.
Lamellas 2.gh (13.8 KB)
I can see now how your code works (and many ways I would do it differently) but I don’t understand your objective? What do you mean by “the lamella angle would follow the curve’s Y‑value”?
This is one possible interpretation of your goal.
Lamellas_2025May4a.gh (17.9 KB)
The purple group should be replaced with a ‘Height’ slider. Is 15500.0 = 15.5 meters? 
I know better than to start work when the description is not clear.
Thank you Joseph for your aswer. The idea was that Lamellas would rotate according to curve function according to Y-value and X-axis the lenght of the curve.
. Below simple drawing.
Apparently we have a language problem because that still makes no sense to me?
Refactor of “plain vanilla” version:
Lamellas_2025May5a.gh (9.2 KB)
Wild stab in the dark at interpreting your objective as depicted in your “simple drawing”:
Lamellas_2025May5b.gh (19.1 KB)
I’m sure it’s wrong. @inno, your mind reading skills might help here?
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OP might want to use a separate curve drawn in Rhino to define the angle of the lamellas (I guess using remaps on its bounding box y domain)
Lamellas_2025May5a_clairvoyance1.gh (20.8 KB)
maybe the function to be used to define rotation is too complex/irregular to be represented by a graph mapper?
or maybe a graph mapper wasn’t taken in consideration at all but it would be the answer 
Lamellas_2025May5a_clairvoyance2.gh (20.2 KB)
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So three possibilities? Thanks. I had imagined a few more… 
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That’s actually similar to what I did above (version ‘May5b’, purple group) except I used the same curve and oriented the bounding box using a line between end points. I reparameterized the “Flat Box” surface so Y coordinates are in the 0 to 1 domain. Maybe it’s correct 
By the way, your “separate curve drawn in Rhino” is not internalized.
Another method would use a “curve function” that generated the rail curve, but none was posted.
P.S. It is interesting to use the X coordinate instead of Y:
And to increase the range of the ‘Angle’ slider from 90 to 180.
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Thank you Joseph and Inno for your great help and contribution. Plenty of ways doing lamellas for a rookie.
Yes, there are many ways to do this. Unfortunately, I’m not confident that we ever understood what you actually wanted and tried to describe with your “simple drawing” and “curve function according to Y-value and X-axis”. That’s a problem.
Also, it would be difficult to build when angles always change, as in the code we posted. I imagine it would require a list of 200 angles relative to the curve tangent at each point.
Hello Joseph and Inno. I apologize for not explaining the matter more clearly. Idea was creating lamellas between 2 separate curves that can be easily edited and there changing the angle of lamellas. Here is a rhino file to show the idea.
Lamellas between 2 curves.3dm (13.3 MB)
Lamellas_2025May8a.gh (16.3 KB)
Geometry (two curves) internalized, no need for Rhino file - so works in R7.
Great! Can’t find function that would alter the lemmella angle.
There aren’t many components to choose from in today’s code. I can’t find anything in any of your posts that explain how you want the lamella angles to be altered.
I matched the Rhino file you posted.