Is there a way to constrain UV unfolding to one axis? (Horizontal or vertical)

Hello blender friends!

I switched to Blender from Maya about a year ago and I’m loving it!

One huge thing that’s missing though is the ability to unwrap along only one axis in UV space. The usual workflow when unwrapping an object, especially if you’re using directional tileables or trim maps (that may or may not have perfectly quad topology) is to planar project the entire strip, say a crown moudling, from the side, add a single seam, and unwrap horizontal. This will constrain the unfold so it can only unwrap left or right, not up and down, which if you’re using trim mapping will keep everything nicely aligned your trimsheet. This works regardless of topology, unlike the myriad of other things I’ve tried in Blender – Rectangularize, UVSquares, Follow active quads, all require your topology to be perfectly quadded out, which may or may not be the case in a lot of scenarios. Let’s say you have a drink bottle that tapers at the top, and like many game models it has some edges kited, so essentially the uv boundary is still a rectangle (it’s a cylindrical object with a single seam down the middle) but the interior has triangles or irregular quads.

Does anyone know of a tool in Blender or a plugin that can constrain unfold to horizontal or vertical axis?
If not was thinking about writing a script that would cache the original vert positions in UV space, do a full unfold, and then restore the vert positions but only in either the U or V dimension. This would keep everything perfectly aligned with your trim map.

Thanks in advance for the help!

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U mean like this? :

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so how did you do? did you use the same topology as the one he shows?

Hi Liam,

MagicUV has an option called Unwrap Constraint. This feature is just available in the 3D viewports panels. You can constrain unwrappings to keep u or v or both from being modified. But its just working with conformal and anglebased mappings.

Beside that this is the result if you use the cylinder projection with an axis aligned aligned view.

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I am not sure if this add-on can do it, but maybe check UV toolkit 2.0:

It is a paid add-on though, so make sure that it can do what you need before you purchase if you plan to. I don’t have it unfortunately so I can’t test it.

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What I did; no addons requied
1.when you done with seams:
2. select desired polygons
3. press U- reset UV
4. Go to front view and make sure that active polygon is recentagle
5. Press U- follow active quads.

Are you sure it works with the topology he’s showing?

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U are right, it won’t. So therefore simply cylinder projection under u menu…


oh yes you’re right, I couldn’t make this option work previously, I don’t know why…

by default cylinder projection use view 3d to define poles of object.
This mean unwrap will be diferent when take from another view. One may change it in last operator to be aligned with object instead view.

no my view was orthogonal to the object, anyway… :wink:

Hey everyone, thanks so much for the thoughtful replies!
@Debuk Awesome! I’ll try it out, thank you!
@MateuszMielnicki & moonboots Thanks for helping, that definitely works out really well for cylindrical objects, I’m going to try out and see if it works out in a generalizable way on an object like this, which is intentionally extremely messed up and non quad topology wise:

So in Maya / Max / headus, you would do this by projecting from front view (the parts that face directly up would be squished in uv view) adding a seam along the inset, manually pulling out the strip that follows the length of the inset, and unfolding vertically for the top parts to get unstretched. This should result in perfectly straight uvs in theory. I’ll try it out! Thanks again

@Debuk Looks like Magic-UV does exactly what I’m talking about! Thanks!

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