About mesh unfolding


#1

Hello all,
I apologize for my bad English writing, but I hope it is enough to let you understand my needs.
I wonder if the Grasshopper and its TT Toolbox plugin can do what I need, and before spending a lot of time learning both Grasshopper and TT Toolbox, could you please tell me if this tool will be able to do this for me :
I need to transform a rounded surface in triangle meshes, then chose the lines to cut some joined meshes, then to align these ones on a plan.
For instance, imagine a portion (a quarter) of a sphere. I need to plan pieces of this form for laser cutting fabric, in the goal of sewing the fabric to reproduce the quarter of the sphere in real life.
So in abstract : doing “surface to mesh”, then chose and align these meshes on a plan to finally make a DXF file with this for laser cutting.
I know “ExactFlat” Rhino plugin, but alas it can stretch the fabric and so it is not what I need.
So : will GrassHopper + TT Toolbox be the right, fastest and easiest tool for doing this ?
(BTW if you have an idea of “how to do” this, it will be welcome too !)
Thank you very much for your time and your tries helping me.
Cordially,
Guy


#2

It is geometrically impossible to flatten/unroll portions of a sphere as it has double curvature. You will need to decompose your overall form into developable surfaces in order to unroll them.

In Rhino/Grasshopper, this may be done in several ways:

If your overall form is a mesh, you could use the Ivy grasshopper plugin (for unstructured triangle meshes) or the mesh stripper/unroll components from Kangaroo1 (if the mesh is structured, such as a standard pole-to-pole sphere mesh would be). I assume that the TT Toolbox unroll component likely implements the RhinoCommon Unroller Class. This may be used in cases where you overall form is composed of a Brep or a collection of Surfaces.

So, quite a few options and I’m sure there are many more.


#3

Hi Anders,
So reading you I guess what I need to do is possible. (and of course as you probably already understood “meshing” in triangles is a way to be able to develop a surface having double curvature at start)
I have to say I don’t quite understand all what you describe, so if you can send me on a user (ie : not developer oriented) tutorial showing how to do what you are talking about, it could be absolutely helping for me !
Best regards,
Guy


#4

I would suggest downloading Kangaroo (below version 1.0) and Ivy and see if you can find some examples of using those plugins to develop mesh strips into the plane (i.e. unroll). The Grasshopper forum should have plenty of examples. While I coded these myself, these two videos should demonstrate the two overall principles I’m talking about:

1) Unrolling a structured quad mesh (could be done with stripper + unroll components in Kangaroo):

2) Unrolling an unstructured triangle mesh (could be done with Ivy or other graph based approaches)


#5

Wow !
You just convinced me to spend my time learning more Rhino, Grasshopper, Kangaroo, Ivy and so on !

(BTW why Kangaroo under version 1.0 and not the last one, the v2.3.2, who seems to be just released ?)


#6

The components I am referring to are part of the Kangaroo mesh utilities. These are not part of the Kangaroo Physics solver components as such, and have therefore not yet been ported to Kangaroo2+ (at least last time I checked :wink:)


#7

Thank you very much, Anders :smiley: