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How can I Bevel the top half of an object or just the top half of a selection.

I have a well plate object created in Geometry nodes.

img1

img2

When I use the Bevel modifier it of course does the entire object.

im3

I would like to bevel just the top half of the hole and/or the top outside edges using Geometry nodes. (see red arrows)

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Rick T
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2 Answers2

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This one goes for topology that will subdivide well.

It makes use of a 'Birail' group, which sweeps a profile curve between 2 bounding 'rail' curves. It works by using Curve To Mesh twice on the profile, once for each rail, with the origin of the profile at opposite ends.. 'down' from one rail, and 'up' from the other. It then mixes the two resultant meshes, factored by distance along the profile:

enter image description here

.. for this kind of surface:

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The group could certainly do with some refinement.

The steps to the top-bevelled object:

enter image description here

Grid.. normalised center cells.. faces deleted.. duplicated.. rings extracted and turned to curves:

enter image description here

below..

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(With those curves for rails,) a profile curve is made from an acyclic curve-quad, with one wide fillet and one narrow one. Swept with the Birail group, and joined back to the original geometry:

enter image description here

After tiling, the exterior edges are extracted, as for the inner bevels, and another filleted acyclic quad is Birailed to make an exterior bevelled trim.

Once joined, the resulting topology behaves well when subdivided:

enter image description here

Maybe a bit OTT for this one (again). But I think when the Birail is tuned up, it could be useful for other bevels, curved creased panels, etc.

enter image description here

Blender 3.2b

Robin Betts
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  • Incredible, you keep surprising me with your great ideas and extensive knowledge of math, mesh topology and Geometry Nodes ...wonderful! – quellenform Jul 25 '22 at 23:49
  • ...we leave the rounded edges at the corners just so, also looks good :D – quellenform Jul 25 '22 at 23:51
  • @quellenform Thank you! That's very flattering, coming from you! If you mean the curved concaves on the exterior .. haven't figured those, yet . .( – Robin Betts Jul 25 '22 at 23:57
  • You two are intense the creativity in this group warms my heart, makes me think anything is possible. – Rick T Jul 26 '22 at 04:03
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I'm afraid this won't be possible, because you can't create vertex groups with Geometry Nodes.

But maybe the following approach will help you, if you can live with the bevel at the corners:

enter image description here

I took the liberty of completely rebuilding the whole thing because I just thought it was funny.

Here I simply subdivide a quadrilateral curve with Resample Curve, convert the curve into a mesh and extrude the edges.

I then shape the inner edges into a circle.

I simply instantiate this surface at the points of a grid, merge the vertices and extrude the resulting mesh upward a bit.

However, I don't create a bottom face at this step, so I get a mesh that is not closed.

Then I apply the bevel modifier (!).

Unfortunately, I can't selectively round edges here because, as I said, there are no vertex groups available.

However, I end up adding another Geometry Nodes modifier, and create the bottom face and create a closed mesh:

enter image description here

Unfortunately, this is the only possibility I could find in a hurry.

Calculating a bevel in Geometry Nodes alone would be too complex...

quellenform
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