Unroll

Is there a component in Grasshopper that can be used to unroll cylinders without having to bake the cylinders and unroll them in Rhino?

Replies to This Discussion

Permalink Reply by Tuan N. Tran on September 30, 2011 at 12:00pm

A cylinder is a rolled up rectangular surface. The height of the cylinder is one edge and the circumference of the caps is the other. Once you have these dimensions with a little math, making a flat rectangular surface would be easy.

Permalink Reply by David Stasiuk on September 30, 2011 at 12:10pm

Tuan's right...doing cylinders by math is probably the easiest. But if you have less regular surfaces, you can use a VB script. Just specify "x" in your input as a surface.

Private Sub RunScript(ByVal x As Surface, ByVal y As Object, ByRef A As Object)

Dim unroll_srf As New Rhino.Geometry.Unroller(x)

Dim crv As Curve() = Nothing

Dim pt As Point3d() = Nothing

Dim txt As TextDot() = Nothing

A = unroll_srf.PerformUnroll(crv, pt, txt)

End Sub

Permalink Reply by Gabrielle Sacknoff on September 30, 2011 at 12:53pm

Yeah... the thing is, I have a lot of pipes each with quite a bit of geometry on the cylinders (cut outs) and varying edge conditions. I'm trying to find a way to unroll all of them, while preserving the cut outs in them without having to unroll each individually.

Permalink Reply by Gabrielle Sacknoff on September 30, 2011 at 12:54pm

Oh, I didn't see that script before, I'll give it a try.

Permalink Reply by Gabrielle Sacknoff on September 30, 2011 at 12:58pm

David,

I have created the VB component, but where does it output the unrolled geometry?

Permalink Reply by David Stasiuk on September 30, 2011 at 2:54pm

This is my first time playing with this feature. Looking at it again, it seems that running the unroller with your pipes input as breps works better. It takes each element you put into it and then unrolls it to the world xy plane. It's pretty straightforward to reorient the unrolled surfaces to new planes. I've attached a couple files that do the trick.

One thing...I did this in Rhino 5.0...just now checked to see if it works in 4.0 and it doesn't appear that the Rhino.Geometry.Unroller is available there. The 5.0 beta is worth getting, anyway!

Attachments:

unroll.jpg, 132 KB
unroll.gh, 5 KB
unroll.3dm, 19 KB

Permalink Reply by Gabrielle Sacknoff on September 30, 2011 at 6:58pm

I went about Pieter's method and have them laying flat now, but I am curious to look at your script. You're saying the Grasshopper definition won't work unless I download the Rhino 5 Beta?

Permalink Reply by David Stasiuk on October 1, 2011 at 12:24pm

It seems so. The Rhino.Geometry.Unroller looks like it's only available to the newest Rhinocommon in Rhino 5.0.

Permalink Reply by Gabrielle Sacknoff on October 3, 2011 at 10:09am

I'm going to see bale downloading 5 today.

Another thing I was trying to work out was a way to "select curves on surface to unroll" like the Rhino command allows you to do.

Permalink Reply by Pieter Segeren on September 30, 2011 at 1:17pm

Hi Gabrielle, is this what you want? :

Permalink Reply by Gabrielle Sacknoff on September 30, 2011 at 1:33pm

Pieter,

Thank you very much, it unrolls my pipes, however, something goes wrong. The pipes are 1" diameter which would produce a circumference of 3.14" but the unrolled surface is 4"... Any ideas on what might be happening?

Thanks again for your reply.

Permalink Reply by Pieter Segeren on September 30, 2011 at 1:47pm

I should have determined the actual lengths of the cylinder instead of using the u and v domains ...