I build the hull and use a subdivision surface modifier. I know that if I want to sharpen an angle on the outside, to use Shift + E.

But how can I sharpen that angle so that is inward? As you can see in the picture, there is a curve. I have tried but can't find a solution.

I would like to remove the curve in the picture and turn it into an angle. I am grateful if anyone can tell me how to do it!

enter image description here

  • $\begingroup$ You have a concave face, + an N-Gon, both are not so great when using subdivision surface modifier. Is it better if you add a creased edge there ? i.sstatic.net/UPeSu.png (Use J to join the 2 vertices, not F) $\endgroup$
    – Gorgious
    Commented Jan 6, 2021 at 14:30
  • $\begingroup$ Indeed. I got the desired result using F. Thanks! :) $\endgroup$
    – Marten
    Commented Jan 6, 2021 at 14:40

2 Answers 2


This face is an N-Gon which notoriously doesn't bode well with subdivision surface, and it is concave, meaning there is an interior angle > 180°, which also can create artifacts.

By joining the 2 vertices with J or Vertex > Connect Vertex Path and increasing the crease on the new edge, you will be able to make the subdivided mesh adhere more to the base mesh.


Although you now have a triangle to get rid of, but this is another topic :)


To keep your topology clean, you can model the shape as if there were no cutout and use a vertex group with a mask modifier to remove the section.

For this example, I added the two selected vertices to a new vertex group by pressing ShftG and then selected that group in the mask modifier. At first, the mask modifier will hide the part of the model that isn't in the group, but by clicking the button on the modifier, it will invert the group weights, hiding the correct vertices.

Keep in mind that any vertices that neighbor unhidden ones will still affect you final geometry's curvature.


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