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Preserve UV Seams when applying a bevel modifier with an even number of segments.
When applying a bevel modifier with an even segment count the original seam edge remains. This edge should be considered the new seam but instead we get a seam that is completely wrong. In addition when applying the bevel modifier it will break the existing UV unwrap. For example, this set of UVs: [![](https://image.prntscr.com/image/DDOfD1mNSUu7gAkTYFLDzQ.png)](https://image.prntscr.com/image/DDOfD1mNSUu7gAkTYFLDzQ.png) When a bevel modifier is applied to give support loops will result in these UVs: [![](https://image.prntscr.com/image/IR5Hh2xbRZiBE88U0GyaUw.png)](https://image.prntscr.com/image/IR5Hh2xbRZiBE88U0GyaUw.png) Which may seem fine at first glance but zoom in and you will start to find little tears and breaks in the island: [![](https://image.prntscr.com/image/kzTAd37ARj2nWsJva5LTYA.png)](https://image.prntscr.com/image/kzTAd37ARj2nWsJva5LTYA.png) Alternatively we could perform a seams from islands to really see our new UV seams. Here is an illustration that shows some of the issues we get. [![](https://i.imgur.com/OkHxXLG.jpg)](https://i.imgur.com/OkHxXLG.jpg) This may seem like small problems and an easy fix but when creating meshes ten or hundreds of times more complex than this the time required to fix these issues multiplies too.
Preserve UV Seams when applying a bevel modifier with an even number of segments.
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Comments(6)

Fweeb · a month ago
So would this replace the existing behavior or be a toggle-able option?
0 points reply
jacrossiter.art [OP] · a month ago
Replace. As it doesn't really serve any useful function as far as I can see. The worst of it is that the UV's break too, splitting in weird places. I just spent the best part of the day fixing the issues cause by applying a bevel modifier to my asset. (it's rather complex of a piece)
1 point reply
jacrossiter.art [OP] · a month ago
I have updated the post with a few more examples and illustrations.
0 points reply
Fweeb · a month ago
Fixed to show the images in-line. What's the solution when there's an odd number of segments?
0 points reply
jacrossiter.art [OP] · a month ago
Thanks! for an odd number of segments it could just use the original method where it damages the UVs as the original edge isn't really being preserved. Either that or to select one of the new edge loops and set that as the seam. But if the user specifically sets the bevel modifier to have an even number of segments as a way to preserve the original edge and it's seam location then blender should do its best to respect that. As the current result isn't useful for anything really.
1 point reply
jacrossiter.art [OP] · a month ago
I'm in contact with a dev trying to work out a solution https://developer.blender.org/T48583
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