I have this model of a rook (chess piece) and I want to subdivide the top edge loop, but as soon I try to do that it forms a weird curvy edge loop. I have attached the model along with the pictures below... before subdividing

enter image description here

Blend file: https://drive.google.com/open?id=1am0JbAVkdK4IXxjiKeEJKan30a5MnJTq


Why it happens:

When you subdivided the top loop, two things happened:

  1. You created n-gons, which behave differently with Subdivision.
  2. You made the loop to look more like an octagon.
    It's a real pain to repair these issues, not worth your time :).

Smart solution :

Use the Screw modifier instead:

  1. Keep only one side edge of your object.
  2. Add the Screw modifier. That way, you can adjust the number of edges to your needs. You can also change the number anytime you want, until you Apply the modifier.
    And make sure to check Calc Order

Add the Subdivision modifier after the Screw modifier, if you need it.

enter image description here

3D view so you can see better what's going on.

enter image description here

Dumb solution:

You can make any shape into a circle using the To sphere tool.
It's a very useful tool, but in this case it won't help much, because of the ngons.

enter image description here

Further reading: Screw modifier in Blender Manual.

  • $\begingroup$ Speculate that the idea of subdividing the top loop is a step towards creating the battlements (top of castle wall) for the rook. $\endgroup$
    – batFINGER
    Dec 17 '19 at 13:18
  • $\begingroup$ Sure :). But in any case, subdividing only the top loop creates n-gons, which mess up the topology, right? The screw modifier can of course be applied, before adding the battlements. $\endgroup$ Dec 17 '19 at 13:26
  • $\begingroup$ Thanx a lot! I did try the "to sphere" option before but it did not yield the result I wanted, I ended up with the same curvy mess. But the screw modifier seems to be a really clever solution. that being said, does it mess with the subdiv mod? Also what does "Calc Order" ensure? $\endgroup$ Dec 17 '19 at 14:56
  • $\begingroup$ Hi :). Screw modifier works very well with Subdivision, I use it all the time. The Calc order calculates order of edges to avoid problems with normals and shading. $\endgroup$ Dec 17 '19 at 15:58
  • $\begingroup$ You can now mark the answer as accepted , for others in a similar situation. $\endgroup$ Dec 17 '19 at 18:05

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