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I am UV unwrapping a mesh that is roughly a square, but the loops of the mesh aren't evenly spaced. I want to maintain this uneven spacing in the UV map. It starts out looking like this with a default unwrap:

enter image description here

There are various tools that let me turn this into an even grid, such as Rectify from the TexTools addon or To Square Grid from the UVSquares addon, and also various commands from MagicUV (which comes with blender). These give an even distribution, which is not what I need. Snap with Equal Distance from UV squares lets you get an even distribution on only the selected loop.

enter image description here

To Grid By Shape from UV Squares does give spacing that matches the original topology distribution. This is the correct thing. However, this only works for square shapes, and it does not easily let me restore the topology spacing for just a section of the UV map.

enter image description here

What I am looking for is a command or other method to get this sort of spacing, but only on one selected loop at a time. I have found mention of this existing in some old UV unwrapping addons from like Blender 2.6 days, but it does not seem to exist in any of the current UV addons, or as a base feature. Maybe I've just missed it somewhere?

Does anyone know if there is a way to do this, or an addon that can do it?

UPDATE: Here is the Snap to Axis and Snap with Equal Distance commands from UV squares. This is the sort of thing I'm after, but I want an option to snap with the same relative lengths between vertices as on the actual mesh.

enter image description here

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    $\begingroup$ UV unwrapping tries to match the mesh spacing exactly. The problem is, usually it can't, because the mesh isn't flat. Flattening the mesh usually requires either cutting it (seams), or stretching some polygons. $\endgroup$ Dec 9, 2021 at 21:38

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It sounds like you're looking for a "follow active quads" unwrap on "length" mode, rather than the default "length average" mode.

With a follow active quads unwrap, I'll generally start by resetting the UV on one face (the most square in 3D) and then using that reset face as the "active quad" for the unwrap. Here, I'll then select a cross of faces from that active quad and then use a "follow active quads" unwrap (from the 'u' unwrap menu) but change the edge length mode to "length":

enter image description here

From here, we can select subsequent edge loops and follow active quads from the unwrapped quad, again, on "length" mode:

enter image description here

After unwrapping all loops individually like this, we can see how our 3D maps onto our UV:

enter image description here

We can follow this up with a "pack islands" operation in the UV editor to fit it into the 0,1 UV space if we want.

"This only works for square shapes"

Follow active quads only works on quads. However, those quads do not have to be in a square shape. It will work on 3-poles. But how it works on 3-poles is unlikely to be what you want: it will create UV overlap. And working on triangles or ngons is right out. The characteristic of this kind of unwrap is that all edges lay entirely horizontally or vertically on the UV map, and that's just not something that would be possible with triangles or ngons. If you're having trouble figuring out some kind of shape involving poles or non-quads and can show us your desired output, we can probably figure out the system you need to explore to get that output.

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  • $\begingroup$ Ah, I did not realize Follow Active Quads could be used this way. It seems to be the root of some of the tools that turn things into grids of sorts. Good summary of how to use it! However, it isn't quite what I'm looking for with this question. It can operate on Face Loops, but not a single Edge Loop which is what I'm after. Doing so gives more options for getting around the various Triangle and Ngon issues. $\endgroup$
    – Ascalon
    Dec 13, 2021 at 4:04
  • $\begingroup$ @Ascalon Single edge loops don't really have UV-- UV is a property only of face-corners, it doesn't exist without respect to faces. If you can give an image of what exactly it is you're looking for, we might be able to provide a procedure to get that. $\endgroup$
    – Nathan
    Dec 13, 2021 at 5:01
  • $\begingroup$ I understand that it works that way under the hood, but in the actual UV editor you are able to work on edge loops. I've updated the question with a GIF showing some current tools that do this. $\endgroup$
    – Ascalon
    Dec 14, 2021 at 5:03

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