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I am modelling some detail with a hexagonal cutout and try to get the correct topology. What should the right topology for SubD of a hexagonal cutout look like?

The question concerns specifically modeling for subdivision surface, not only how to make a hexagon in a quad polygon. And it’s about simplification the topology.

I’ve have made some example for the topology, I have now. I think it is a little strange. What mistakes have I made? enter image description here

Ivan Sokolov
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    Your question is opinion based, "correct" is subjective, so is "strange". The latter means you intuitively feel there's something wrong with it, and indeed I could criticize a few things, but ultimately you have to ask yourself a question what this mesh will be used for. You probably don't need to optimize the mesh to save a few vertices by doing those loops: https://i.imgur.com/zKiKb7T.png - instead just make the loops go through the entire mesh, preserving a more natural flow: https://i.imgur.com/8ER5xD2.png – Markus von Broady May 08 '23 at 21:26
  • It doesn't matter much on the flat surface, so you might as well dissolve some edges, as long as the resulting n-gon will be completely flat and will be surrounded by co-planar quads (faces with 4 vertices and the same normal as the ngon): https://i.imgur.com/t1JTyuT.png - such ngon will not produce issues when subdivision surface is added to the object, because the interpolations of the shape will happen on the quads surrounding it - still, avoid such ngons because if you have them, adding new loops is harder. Also for subdiv + smooth shading it's actually good to have a buffer of 2 quads... – Markus von Broady May 08 '23 at 21:31
  • Regardless if you listen to the above advice, try to straighten the loops, so they don't go in a zig-zag pattern. https://i.imgur.com/uNN6Lur.png I know what you were going for with those turns, you want the distribution of the net to be even, but you can still select the vertices on the turns of the loops, press [G] key twice and slide a vertex to straighten a loop. Also, try to make loops next to surface angle changes to be at equal distance to those changes, because those are holding loops and they control the shape: https://i.imgur.com/ZqezqRn.png – Markus von Broady May 08 '23 at 21:36
  • Thank you for your helpful and useful comments.

    You are true, I’ve tried to get the uniform distribution of the mesh, so some edges look like a zigzag.

    Is is an interesting idea, to keep n-gons. But I want to get quads always. It is good for SubD and animation purposes.

    I’ve tried to reduce 4-polygon net to 2-polygon to simplify the grid, since it is only part of the final geometry.

     – Ivan Sokolov May 08 '23 at 22:44
  • I don’t understand your last picture. What should the grid look like so that loops to be at equal distance to those changes? – Ivan Sokolov May 08 '23 at 22:52
  • What you show is a pentagon, for an hexagon, this seems to work fine: https://zupimages.net/up/23/19/8q92.jpg – moonboots May 09 '23 at 06:37
  • Pentagon has 5 angles. What I show has 6 angles. It is hexagon =) Your topology is good and understandable, but it works good for simple details. But it creates many edges and I can’t use it in a complex detail. – Ivan Sokolov May 09 '23 at 07:04
  • @IvanSokolov Hey. You flagged as not duplicate, but both questions seem to me to address the same fundamental issue. Connect a quad based topology to an hexagonal hole with subdivision modelling. How is yours different, or could you tell why my answer there doesn't fulfil your goal? – Duarte Farrajota Ramos May 09 '23 at 08:49
  • "I don’t understand your last picture. What should the grid look like so that loops to be at equal distance to those changes?" - If you want the profile of the bevel to be equal, you need the holding loop to be at the same distance, so those arrows should have equal length: https://i.imgur.com/XtTJbyy.png Here's a gif that exaggerates the inequality https://i.imgur.com/L3EY0qU.gif – Markus von Broady May 09 '23 at 08:55
  • @Duarte Farrajota Ramos If I apply SubD modifier to your geometry, it will became a circle form, not hexagonal. Try it yourself. But I need to keep straight angles. – Ivan Sokolov May 09 '23 at 09:52
  • @Markus von Broady Thank you. I've understand it. It is only an example. My goal topology is more complex: https://imgur.com/a/NUhpuN4 – Ivan Sokolov May 09 '23 at 09:57
  • https://blender.stackexchange.com/questions/6425/keep-sharp-edges-when-using-subdivision-surface https://blender.stackexchange.com/questions/150566/sharp-edge-support-loops-for-cylinder – Duarte Farrajota Ramos May 09 '23 at 10:31

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