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My object is like the half ball on this picture but with a closed surface and no holes and I would like to have almost the same result as in the picture but with a closed border, and I would like to be able to have more or less holes in it and to play with its thikness without fill the holes. enter image description here

Notice that my mesh is a bit complex, I already tried to apply some modifiers or to cell fracture my mesh but I didn't have the expected result..

If you have some idea, I would be grateful ! (Maybe voronoi texture node ? I have no idea of how to use it and if it could be a solution)

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  • $\begingroup$ Thx for this answer but it is not really what I want if I understand well your link. Indeed here you begin with a plan object. I begin with a mesh from photogrammetry, so much more complex. Plus, there is no holes at end, isn't it ? $\endgroup$ – art2611 Jul 18 '19 at 14:59
  • $\begingroup$ A Similar process could be adapted to obtain a Voronoi-like pattern. Holes and thickness are easy to add at the end $\endgroup$ – Duarte Farrajota Ramos Jul 18 '19 at 15:36
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That can be done rapidly using Tissue addon (which is included in standard Blender distributions, I think).

  • Add a mesh.
  • Eventually use a decimate modifier to reduce amount of vertices and add some randomness
  • Use the "Dual mesh" button from the 'Tissue Tools' panel
  • Add a wireframe modifier and a subsurface modifier

And voila:

enter image description here

Base setting:

enter image description here

  • 1 Add a mesh
  • 2 Set wireframe display on so that you can preview the result
  • 3 (optional) Add a decimate modifier and tune the ratio
  • 4 Use the "dual mesh" from the "Tissue" addon options

Second step:

enter image description here

  • 1 Add a wireframe modifier, tune the thickness and if needed use the 'relative thickness' option.
  • 2 Add a subdivision surface modifier to round the result.

Refinement:

You can lead the amount of decimated vertices (using 'decimate' modifier) with a vertex group.

So if you define a vertex group, then draw on it, that will allow to choose if Voronoi cells will be larger or thinner.

Here for instance, more decimation for the head and less for the bottom part or ears:

From left to right: vertex paint, decimated result, final mesh.

enter image description here

To do it on part of the model only (should work on quad meshes)

  • Select the wanted faces (you'll need to keep this selection along the steps).
  • Make a base for the tesselation (a square with a hole below that fit to quad faces)

enter image description here

  • Tesselate using Tissue with a limited tesselation on selected faces

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You now have the part prepared for Voronoi.

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Now in the original, in edit mode, as the faces are still selected, delete this faces only (X then 'only faces').

enter image description here

Join the 2 meshes, and in edit mode merge vertices by distance.

enter image description here

Add a solidify modifier (as this mesh is flat and non manifold) and a subdivision surface modifier. You now have something like this:

enter image description here

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  • $\begingroup$ Wow, thx you a lot for your answer !! What an easy way do to it and working so good ! $\endgroup$ – art2611 Jul 23 '19 at 9:03
  • $\begingroup$ Do you know if there is a way to do it locally ? I tried to use a boolean modifier after it but the object is non manifold, so boolean is working really bad.. So if I could do it directly on a part of my mesh, or if you have an other idea ! $\endgroup$ – art2611 Jul 23 '19 at 10:11
  • $\begingroup$ @art2611 no direct idea about that. By locally, you mean Voronoi holes only on a part of the mesh? Is it just for rendering (if so maybe hiding part of the model using nodes). If for 3D printing maybe using a vertex group on the wireframe modifier and superposate original and Voronoied model? $\endgroup$ – lemon Jul 23 '19 at 10:26
  • $\begingroup$ Or separate the mesh in two before Voronoi it (make the Voronoi only on the part you want). $\endgroup$ – lemon Jul 23 '19 at 10:32
  • $\begingroup$ Yes it is for 3D printing ! I already tried nodes yes but as you say it's only rendering so not a solution for what I am trying to do. I also already tried to separate the mesh in two and applied voronoi on a part, and then the problem come when I have to superposate them, because I use Boolean modifier and it apparently doesn't work well.. Maybe there are others way to superpose ? Finally I tried on your advice on vertex group, however, the vertex group option is only available on wireframe thikness factor, so the entire object still in wireframe ! $\endgroup$ – art2611 Jul 23 '19 at 11:09
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Unfortunately there is no way to do this entirely procedurally at the moment, as far as I know. You have to apply most modifiers and preform some Edit Mode operations.

enter image description here

  1. Create a base mesh with whatever starting shape you want.
  2. Ass a Subdivision modifier set to Simple to said object
  3. Adjust the number of subdivisions as desired to obtain a mesh density that suits your needs
  4. Now add a Decimate modifier and turn on the Triangulate option
  5. Adjust the ratio until you obtain a desirable pattern
  6. Add one more Subdivision modifier set to Catmull-Clark with only one subdivision
  7. Once satisfied with the results apply all modifiers
  8. Now in edit mode you will have to preform a repeated sequence of actions to delete all undesirable vertex enter image description here
  9. Select one "central vertex" from the generated "cells" pattern with more than 4 connecting edges, press Shift + G to select similar and choose Amount of connecting edges option. Erase all selected with the option Dissolve Vertex
  10. Repeat this process until you end up with "clean" voronoi cells leaving the vertex with four connecting edges for last

enter image description here

  1. As last step select all "side vertex" that are only connected to two edges and dissolve them as well so you end up with "simple voronoi cells".

enter image description here

  1. Now in face selection mode inset them all using the Individual option, adjust amount as desired. You can at this point optionally add a Wireframe modifier instead of insetting, if you don't care about adding a solid thickness or if different your wires will have a circular section.
  2. Once done exit edit mode and add modifiers like Solidify to add thickness and a Subdivision modifier set to Catmull-Clark for a smooth appearence. Adjust order to achieve desired effect

These last two modifiers can be left "live" so you can control thickess and smoothness procedurally.

enter image description here

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  • $\begingroup$ Thank you a lot for this really precise answer ! That's sad that there is not a way to do it procedurally.. However your proposition is really good and helped me ! $\endgroup$ – art2611 Jul 19 '19 at 14:08

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