Skeletal mesh

In response to this discussion:

http://www.grasshopper3d.com/photo/mesh

I am posting my definition for generating an open foam mesh.

(I didn't post back at the time because there were some troubles with weaverbird back then and I was having to use some ugly workarounds, but now that is all fixed)

To sum up the approach -

take a random cloud of points

generate the 3d voronoi

scale the edges of the cells towards their centres, and also towards the centres of the faces.

connect these 2 sets of scaled edges with mesh quads and join

cull some of the outer faces

subdivide and smooth with weaverbird

(In the video there were some other variations on the smoothing/relaxation, both of the initial point positions and the final mesh, using hoopsnake and/or kangaroo)

Attachments:

skeletal_mesh.gh, 10 KB

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Replies to This Discussion

Permalink Reply by RWNB on March 17, 2012 at 10:24am

Thank you!

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Permalink Reply by Giulio Piacentino on March 17, 2012 at 3:52pm

Very nice discussion! Thanks.

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Permalink Reply by Mateusz Zwierzycki on March 17, 2012 at 4:33pm

I have one favour for you - could weaverbird catmull clark component output vertices and faces in datatree, where each branch represents primary face, (which was smoothened/triangulated) ?

This maybe (I am not 100% sure) will convert our meshes (Daniel's and mine) to geometry based on surfaces.

Here is a little proof of concept :

Mesh on the left was was obtained by meshing a surface.

Next it is rebuilded with surface from grid points component, which results with almost same surface as one used to make mesh (surface on right is made from mesh)

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Permalink Reply by Giulio Piacentino on March 18, 2012 at 4:09pm

Hi Mateusz,

this is interesting: I've spent now a couple of hours of this Sunday evening to see what this would look like. In general, I think the subdivision component is more helpful when it returns a mesh. To put the two things together, here is a script that takes the mesh and separates it into several sub-meshes, each one being the descendant of an original face. This script works in general for this component.

Attachments:

separate.gh, 13 KB

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Permalink Reply by Mateusz Zwierzycki on March 18, 2012 at 5:01pm

My turn ! (only untrimmed surfaces !!!!!!)

Attachments:

separate.gh, 16 KB

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Permalink Reply by Mateusz Zwierzycki on March 18, 2012 at 5:21pm

closed breps :

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Permalink Reply by taz on March 20, 2012 at 2:09pm

On a completely unrelated note, I'm enjoying the HSL "Hue" channel for random coloration. That's the color pallet that shows up in academic papers (I think).

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Permalink Reply by Mateusz Zwierzycki on March 20, 2012 at 6:10pm

http://www.geometrie.tuwien.ac.at/pottmann/2006/hfghp_fracture_06/h...

Close enough !

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Permalink Reply by Giulio Piacentino on March 21, 2012 at 3:46am

This is fun!

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Permalink Reply by Daniel Piker on March 18, 2012 at 8:09am

And here's a way to go from any mesh to a thickened dual

I created a component for the dual operation (trying out the new GHA wizard). It takes a mesh as input, and outputs polylines for the dual (because rhino doesn't support arbitrary polygon meshes).

There is a choice of how the dual vertices are created - either using centres of the circumcircles of the original mesh faces (which gives the Voronoi diagram if the input is a flat Delaunay mesh), or using the barycenters (which seems to work better on curved or very irregular meshes).

Attachments:

Thickened_dual_mesh.gh, 58 KB
MeshDual.gha, 10 KB

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Permalink Reply by Mateusz Zwierzycki on March 18, 2012 at 8:44am

Great, astonishing !

it is getting really serious. I actually have idea how to override connections and points for my ghx, but this need some time with scripting (getting topology from bunch of lines). I hope I will find for it some time soon, cause now I have to do my master degree final.