Disable auto merge UV vertices
Sometimes in UV editor vertices are automatically merged when they overlapped, it may be several or all vertices on the border of the islands, this behavior is not predictable, after that, these islands cannot be selected separately.
I think this is a bug, but the developers do not think so.
This behavior is not useful, but it creates a lot of problems when working with overlapped islands, UV trims and also when baking and texturing.
Use of third-party UV editing software does not solve this problem, usually you need to send mesh to Blender using a bridge and then into baking or texturing software.
So it would be nice to fix it: disable merging or make switchable.
6 Comments
There is no "merged UV vertices" - each polygon, technically, has own UV vertex for each of mesh vertex belonging to this polygon, each with own UV coordinates.
What you talk about is Sticky Selection, you can select one of three modes:
You think this is a bug, you think this behaviour not useful... this thing exist in Blender for more time than, I guess, you know about Blender existence. You need first to learn Blender a bit more.
as i understand problem - it is in 'loosing' uv shells as separate elements inside uv editor when you overlapping them. so its behave weird with shared location activated (but in 3dview still available as separate uvs) imgur.com/a/t9GmCwz imgur.com/a/rb7pBUi no?
^^ this. UV verts that are cospatial, blender will treat like they are "welded". It's a little strange, coming from other 3d software- where they tag the data with additional information, such as which island a UV vert should belong to, but Blender doesn't even have any concept of an "island" at the data level.
In general, because of this problem, my entire pipeline broke. Unfortunately, in some places the blender brings very unpleasant surprises. In this case, I advise you to use third-party applications for UV unwrapping your model. I solved similar problems with overlapping with rizomuv, this program does not have such problems as blender's UV editor. Perhaps a small donation will stir up the interest of developers in solving this problem? I hope the developers will respond about this solution to the problem
This is a big problem, I must admit! Had happen me several times. With overlaping uv, this is a big dilemma. Please fix it soon. :)
Not sure if the same problem, but when working with VRM files created by VRoid Studio, loading them into blender, adding say some bones to make ears bounce (with no changes made to the mesh), and exporting again results in a slightly different mesh. The number of vertices changes. This means any blendshapes defined for the original mesh break (there are tools around to add standard blendshapes to the model). I think it works if you add all the blendshapes first, but it is annoying - you have to get the workflow in exactly the right order when Blender is a part of the overall process.