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Mirror Modifier: UV-mirror offset option
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Benefits: Artists can use the mirror modifiers mirror UV's option while sharing UV textures between models.

Description: The current mirror modifier would have a float option added, which defaults to zero (image center). which can be moved where -1.0 is the left side of the image and 1.0 is the right hand side.



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Campbell Barton (campbellbarton) updated the task description. (Show Details)
Campbell Barton (campbellbarton) raised the priority of this task from to Normal.
Campbell Barton (campbellbarton) renamed this task from Mirror Modifier: UV offset option to Mirror Modifier: UV-mirror offset option.

Thanks for adding this, Campbell!

I'm the one who requested this, so I'll provide another usecase for it:

Some game engines and texture-baking software need overlapping uv-islands (as are often used in game art) to be offset by the width (or height) of the texture. This is what that'd look like:
The process is described in more detail here:

Would this offset be only for the U axis, or would there also be a corresponding offset for the V axis?

I think both would be best, and if possible: a toggle for Normalised coordinates (from the tooltip: 'Display UV Coordinates from 0.0 to 0.1 rather than in pixels) as in the UV editor would be great.

This way you could just enter 1 for the use I mention in my previous post, but you'd have an option to finetune it for things like other uses like unique texturing for each side of the mirror.

edit: Actually, moving it in pixels brings up what I think is an issue: where do we get the texture-size from? In the UV editor this is related to the texture that's mapped to the currently active component I believe, but given that the Uv editor might not be open, this could be confusing.

I've added fields for U and V offsets, which both work within normalized coordinates (as that is what the modifier sees), I think that pixel offsets for mirrored UVs should be their own issue.


I submitted a patch for this a few days ago, mind having a look?

It's my understanding that I'd need to build Blender for this, right?
If so, I've never done that, and I'm not set up to do so. Any chance of a (Windows) Build to test?
If not, I'd gladly just screenshare or something if it's feedback on the implementation you're after moreso than testing stability.

Robert Fornof (amdbcg) claimed this task.EditedMar 5 2017, 5:18 AM
  1. I'll work on this for as long as I can, and try to hand it back if I can't complete the work.
  2. I'm a total noob at this, I'll just assume I ask questions on the dev mailing list , ask in #blendercoders , or bug someone via maniphest.
  3. I may comment extensively here.
  4. I may bug someone about getting stuck , and it may happen soon with something really simple...

I've checked the patch, and it looks like it mostly works.

@michael knubben (michaelknubben): Do you still need a windows build to test on/make sure its working?

1.5 minute walkthrough of this patch :
Is there anything that needs modification?

This looks great!
This may be outside of the scope of this project, but would a vertex group/material mask be feasable?
The intended effect would be for only the masked area to be mirrored (with a possible invert function, as a few other modifiers have)