Grasshopper

algorithmic modeling for Rhino

paper strip model with kangeroo?

I want to make a model of a twisted cylinder.

Saw this video on vimeo and thought maybe Kangeroo would give me a possibility to make it digitally

http://www.curvedfolding.com/video/virtual-paper-test

Can anyone give me a hint how to start?

Its simply a cylinder where you grab two opposite sides and rotate one of the sides to the desired angle.
In the image this is approximately 270 degrees

Views: 6237

Attachments:

Replies to This Discussion

I'm not completely sure what you are going for but I think it might be similar to something that I saw from Lorenz Lachauer. There's an example of a paper strip model on an ellipsoid at http://thegeometryofbending.blogspot.com/. Scroll down about half way on this page to the post from 5/18/2008 to see what I'm referring to.

If I'm on the mark about what you're trying to do then also check out the David Rutten's plugin, ToyCar. http://thegeometryofbending.blogspot.com/2009/03/toycar-plug-in-for...
Lorenz Lachauer also developed two Grasshopper definitions that do roughly the same thing: Surface Turtle and Curvature Turtle. You can get the GH definitions from his blog at http://eat-a-bug.blogspot.com/ You might fight his blog very interesting also. He's doing some really interesting work.
I know all the blogs that you reffer to but none of them seem to solve the "simple" problem i have :-)
As you can see in the pictures its just a simple cylinder that i twist in a physical model but dont know how to set up the relationship digitally to create the surface.
It's also worth checking out this post
http://eat-a-bug.blogspot.com/2010/08/parametric-paperstrip.html from Lorenz Lachauer's blog. The Toy Car is a great tool (that I hope David Rutten will include in GH), however, it requires a base surface. In this case it's not (yet) clear what that base surface should look like.
Also, the Toy Car will produce a curve, and it's not always obvious how to construct the correct (developable) surface from this curve.
I think the Kangaroo could be useful here, but Daniel Piker is really the person to answer that, did you try emailing him?
Hi Mårten, Thank you for the comment
However as i also replied to Jerrod the solutions proposed at the blog you reffer to do not solve the problem. And yes I already tried to mail Daniel Piker but no answer yet.
Its not like i want to fint plank lines or geodesic curves on a freeform surface.
What I have is just a plain cylinder that i twist by hand in a physical model, but wants to do it digitally.
Yeah, if only things were as simple in the digital world as they are in the physical! :-)
(Take for example real-time daylight rendering, it just happens in the real world...)
My belief is that somewhere there is probably a simple answer to your question, but you may have to try some detours to find it...
Anyway, it's an interesting problem and I would very much like to know the answer too...
Yes i didnt mean to offend anyone but for me the problem seems simpler than finding geodesics, at least in theory :-)
But yes finding solutions you always need to make detours to arrive at a solution in the end :-) But thanks for the comment

Actually I already started on it about 1 hour ago, so just before you sent the last reply.
A coincidece that we thought of using the same technique
However i tried with triangles in this first step but i will try with quads as well.
Thank you
Actually i tried to make a lofted surface from the centerline of each triangle and i turns out to be almost a straight strip when i unroll it in rhino so thats a step forward
then i just need to adjust the angles to make up the desired strip than closes up on itself

Careful when picking what lines to loft! The straight lines in the surface on the right are not aligned correctly with the ruling lines of your single-curved surface. Which means: it will be slightly double-curved.
It will still unroll to a straight strip, but it may not be quite the surface you are looking for.
See yellow line in image below for correct loft line example:

but how is this different from the the lines of the quads you suggested?
When i try to make the ruling from the lines of your guads i get the same deviation
Is it not just a matter of how close the lines are to each other?
Yes okay i get that the rulings should not be perpendicular to the edge, but i still dont get how you will do it from the quad example
Can you maybe make it in rhino and post it as before?
And for the example with the elipses how did you then find the fulings in the correct example?

if I just loft the lines in each fold you still dont get a perfectly straight strip as you can see in the image below.

by Evan

by Evan

by Evan