Why do I have to manually split normals on this model?

[bvz2000]

Hey there,

I have a model that I want to shade smooth, but the display looks terrible. As far as I can tell, what I should do is set the normals to auto-smooth and adjust the angle until only those faces below a certain threshold are smoothed.

But nothing seems to work. It still shades weird. When I look at the vertex normals I can see that they are unified and at an angle. My reference cube shades correctly with the same settings, so there is something somewhere that I have set (or not set) that is causing this to happen. But I can’t seem to figure out what it might be.

Edit: If I set the normals of the reference cube to face, then it also behaves badly and I can’t figure out how to get back to the “default” behavior.

I can manually split all the edges that I need sharp and that works.

Any thoughts?

All the help I get here is amazing and I really appreciate you all taking time to help me!

broken_normals_v001.blend (957.4 KB)

[Okidoki]

You might just shade the flat surfaces… flat like so ?? :

Because Smooth shading over a 90 degree angle always look weird…

ohh… or simply use the edeg split modifier…

[bvz2000]

Thanks!

I found another solution. Apparently this model has a custom split normal and that is messing with the normal display.

If you remove the custom split normals it works as intended.

[Okidoki]

Ohh yes indeed… if imported from some exchange file format this sometimes is needed… but mostly not for blender