Inward Extrusion (Or Hole) On Curved Surface Display Smoothness Problem

[Anonymous]

Hello,

I have what I thought was a simple task but after several hours of experimenting, internet searching, and colleague consultation, I have yet to come up with a solid answer so I'm hoping someone  here can give me advice. Note that I don't want to use Maya smoothing (ie. hitting '3') since I want to export this into a game engine that doesn't handle that.

I am simply wanting to have an inward extrusion of a square or simple shape (or even a hole) on a single face of a cylinder. The problem is, when I do this introduce edges and points with new normals that cause a visual aberration where I want it to look smooth up to the edge of the extrusion. Does anyone have any ideas about how I would achieve this? Any advice would be appreciated.

Below are pictures of the issue.

Geometry:

Geometry

Viewport:

Viewport

Render:Render

[trs_andre]

Hi!

I believe it might have something to do with the normals (you can see them by clicking in Display Menu, Polygons, Vertex Normals, or Face Normals).

When you extrude the face, you are adding edges, but they are in the same "relative position" as the original face (they are all in the same "big face"). Because of that, the edges you added are closer to the center of the cylinder than the original ones, so it doesn't create a clean curve with the other ones.

If you want it to be smoother, I think you should add edge loops in the position you want to extrude, and extrude the face only once (to the inside), because if you extrude scaling, it will create new vertical edges again only in that place, making it not smooth again.

Hope this tip helps!

[Anonymous]

Thank you for taking the time to respond. I tried your idea and indeed working directly off of edge loops seems to be the way to avoid this issue. The only other trick I needed was to have consistently spaced edge loops. If there is an edge loop that is closer to one side than the other, you still get a weird lighting anomaly. You can, however, gradually increase the spacing away from the higher density spot with the extrusion, which you could do to reduce poly count across the entire object where you don't need high poly count. Thanks again for the tip. I included some screenshots of a slightly more advanced version of what I initially asked as demonstration for anyone else who reads this.

[trs_andre]

Happy to help!

I believe it is a matter of searching for the balance between the edge/polygon number, and the returned result 🙂

By the way, in the hole edges, "Edit Mesh" Menu, "Bevel" Tool might be handy! (If you are not using it already) 👍