# Modify an object using a control curve

**URL:** <https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096>\
**Category:** Rhino\
**Tags:** windows\
**Created:** [December 1, 2025, 10:03pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096 "2025-12-01T22:03:46Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![davidgolber](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidgolber/32/632251_2.png) [@davidgolber](https://discourse.mcneel.com/u/davidgolber)\
**Post date:** [December 1, 2025, 10:03pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096/1 "2025-12-01T22:03:46Z")

</div>

[example.3dm](https://discourse.mcneel.com/uploads/short-url/2zfvAaMrJ4G7TltFATyHyDfqMPJ.3dm) (155.5 KB)

I have a complicated object. I want to pull one end of it a certain distance in a certain direction, and have the changes drop off to zero at the other end, in such a way that tangents don’t change at the other end. The example shows what I am trying to do. The original object is the black rectangle. The red rectangle is what I want to produce. (Part of it is hidden by the black rectangle.)

The red line is what I am thinking of as a “control curve”. The deviation of that control curve from the black line below controls the distortion of the object (the rectangle).

Can I do this with “Flow along a curve”?

PS: I am using Rhino 4.0. Do I get a prize for “most ancient”? 🫠

---

<div class="post-metadata">

**Author:** ![davidgolber](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidgolber/32/632251_2.png) [@davidgolber](https://discourse.mcneel.com/u/davidgolber)\
**Post date:** [December 1, 2025, 10:16pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096/2 "2025-12-01T22:16:08Z")

</div>

“Flow along curve” does something similar to what I want, but not exactly. (I tried all the options.)

What needs to be done: Get all the control points of all the parts of the object. Move them as described by the control curve. (x and z don’t change; y changes …)

---

<div class="post-metadata">

**Author:** ![Tom\_P](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/tom_p/32/766520_2.png) [@Tom\_P](https://discourse.mcneel.com/u/Tom_P)\
**Post date:** [December 1, 2025, 10:32pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096/3 "2025-12-01T22:32:54Z")

</div>

> [@davidgolber](#):
>
> a complicated object.

you have to be more specific about this.  
what s the “complicated object” ?  
will it be completely inside the rectangle ?

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/7/d/f/7df504527c0fe9a913c83744bd25e75bddaf4b99.png)

and yes it s possible.  
for sure with CageEdit  
maybe with flowAlongSrf

i do not know - if with rhino 4

like this ?  
done with flowAlongSrf

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/e/b/b/ebb438750a01d67d7b547d057d5bcaf7ee392024.jpeg)

[flowAlongSrf\_HelloWorld\_tp\_rh4.3dm](https://discourse.mcneel.com/uploads/short-url/kMkLaUagMWqguP6Vx67mPO4bCq1.3dm) (1.2 MB)  
[flowAlongSrf\_HelloWorld\_tp.3dm](https://discourse.mcneel.com/uploads/short-url/iIsKYGSD5RmKTPkfpw103HxBl9f.3dm) (3.9 MB)

kind regards - tom

---

<div class="post-metadata">

**Author:** ![davidgolber](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidgolber/32/632251_2.png) [@davidgolber](https://discourse.mcneel.com/u/davidgolber)\
**Post date:** [December 2, 2025, 4:12pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096/4 "2025-12-02T16:12:07Z")

</div>

Yes, Flow Along Surface does what I want. Thank you very much.

---

<div class="post-metadata">

**Author:** ![Tom\_P](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/tom_p/32/766520_2.png) [@Tom\_P](https://discourse.mcneel.com/u/Tom_P)\
**Post date:** [December 2, 2025, 6:22pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096/5 "2025-12-02T18:22:38Z")

</div>

solved ? please mark my post above as solution - so others don t need to dig into the topic.  
kind regards - tom

---

<div class="post-metadata">

**Author:** ![davidgolber](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidgolber/32/632251_2.png) [@davidgolber](https://discourse.mcneel.com/u/davidgolber)\
**Post date:** [January 13, 2026, 10:18pm UTC](https://discourse.mcneel.com/t/modify-an-object-using-a-control-curve/213096/6 "2026-01-13T22:18:57Z")

</div>

I will add one more comment, from recent experience: You need to be careful how you make those “surfaces”. If you make ‘em wrong, it looks like the surface you want, but it’s actually a trimmed surface, and the UV parameters don’t run all the way from 0 to 1 in both directions. You can check by looking at UV coordinates of points near the four corners of each surface.