What is the best way to wrap these curves around a unrolled polysurface?

Rhino
1

I’m trying to wrap some curves around a simple extrusion, but I’m lost as to what the best method would be.

image
image1519×1630 107 KB

2023.03.10_Rhino_forum01.3dm (70.0 KB)

2

Could you just project them through?

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3

No, because the curves are at a slight angle as they’re meant to create a wrap similar to the wire wrapping in the image below…

4

Ah, that makes sense.

5

So like this?

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6

Hello - I think this, maybe?

2023.03.10_Rhino_forum01Maybe.3dm (172.1 KB)

-Pascal

7

Not quite. The operation should result in a continuous spiral curve up the shape

8

Maybe this?
That is if the goal is just a curve that spirals up the shape.
Helix, Line, Sweep1, Intersect

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ViewCapture20230310_131650
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9

Yeah, but when you intersect a helix with a triangular profile like that, I don’t think the curve would have the same slope all the way up. In other words, if you unrolled that curve, you’d see a subtle wave in it. You can even see a subtle wave in your first image where the curve flattens a but as it enters the curved portion of the triangular profile.

10

Yeah, how did you do it? It looks like you made a new surface (in blue) to use as the reference surface?

11

Earlier, I found a hacky solution where I placed the line segments in the correct vertical positions on the straight portions of the triangular shape, then blended between them, and then pulled that blended segment to the round segment of the shape.

12

Correct - I made a little target surface for FlowAlongSrf

  • BoundingBox on the two flat curves.
  • Maneuver a copy of this up to the target object and project - or just two lines that are the right distance apart.
  • Loft the two projected curves. Use Rebuild on the loft dialog - 32 or more points, I would say. The object is to get a clean, evely parameterized surface that is very close to the target.
  • Make a planar surface from the original bounding box rectangle.
  • FlowAlongSrf from the flat surface to the loft.

-Pascal

13

It would cool if FlowAlongSrf could work with Polysurfaces, but I see how that would be challenging too.

14

Ah thanks. Learn something new every day. :slightly_smiling_face: