Smart UV project sometimes doesn't align the islands properly #116355

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opened 2023-12-19 16:58:21 +01:00 by Adam Preisler · 3 comments

Adam Preisler commented

2023-12-19 16:58:21 +01:00

System Information
Operating system: Win11
Graphics card: 4090 RTX

Blender Version

Worked: (3.5)

Related issue
#110724

Short description of error
I've reported problems with the "Smart UV Project" operator's auto-align of the UV islands and they were fixed for the model that I supplied last time but now the issue seems to still be there for another mesh that I share here. Bug_Smart-UV-Project_Still-A-Problem.blend

Exact steps for others to reproduce the error
Open .blend, in the 3D view go to UV > Smart UV Project > OK
Then you can see that some of the islands are aligned horizontally and some are vertically. I am not sure why but they should all be aligned vertically and they used to be in Blender versions before 3.5.

Blender 4.0

Blender 3.3.12

**System Information** Operating system: Win11 Graphics card: 4090 RTX **Blender Version** ![image](/attachments/2260ae26-cc8e-42b0-aa87-8d06eb7d5a4b) Worked: (3.5) **Related issue** https://projects.blender.org/blender/blender/issues/110724 **Short description of error** I've reported problems with the "Smart UV Project" operator's auto-align of the UV islands and they were fixed for the model that I supplied last time but now the issue seems to still be there for another mesh that I share here. [Bug_Smart-UV-Project_Still-A-Problem.blend](/attachments/8463ef55-1015-4365-8e80-24b72ab36c7e) **Exact steps for others to reproduce the error** Open .blend, in the 3D view go to UV > Smart UV Project > OK Then you can see that some of the islands are aligned horizontally and some are vertically. I am not sure why but they should all be aligned vertically and they used to be in Blender versions before 3.5. Blender 4.0 ![Screen Shot 12-19-23 at 04.49 PM.JPG](/attachments/998f4d36-b24b-427c-9ce1-9b33454fbe35) Blender 3.3.12 ![Screen Shot 12-19-23 at 04.52 PM.JPG](/attachments/5bb9d279-25fc-493e-bb7c-3c0b8e91e9ba) ![image](/attachments/2cecb616-808d-49e7-8690-b434e1983b82)

Screen Shot 12-19-23 at 04.49 PM.JPG

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Bug_Smart-UV-Project_Still-A-Problem.blend

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Screen Shot 12-19-23 at 04.52 PM.JPG

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Adam Preisler added the

labels 2023-12-19 16:58:22 +01:00

Pratik Borhade commented

2023-12-20 06:50:33 +01:00

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cc @Chris_Blackbourn @brecht

cc @Chris_Blackbourn @brecht

Pratik Borhade added

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labels 2023-12-20 06:50:50 +01:00

Brecht Van Lommel commented

2024-01-03 17:32:53 +01:00

Owner

That last screenshot looks odd, but the model for that is not attached so I can't investigate that. Can this be attached?

For the other case, it's not obvious that all islands should be oriented along the longest axis. For this model it makes sense. But it's not necessarily the most efficient way of packing, or the direction that a user would consider natural.

I don't think either the new or old packing method was designed to do this, it was mostly a side effect where depending on the model it may or may not work out like that.

The Pack Islands operator in the UV editor is the place where there is more control over the packing strategy. Using a different Rotation Method there seems like it orients the islands along the longest axis, but I think this is also somewhat accidental. Adding a rotation method that does this explicitly would be a good feature to add.

It's not obvious to me that Smart UV Project should be changed to work like that, whatever strategy we use there will be suboptimal for some model.

@ideasman42, do you have an opinion on the packing strategy for Smart UV Project?

That last screenshot looks odd, but the model for that is not attached so I can't investigate that. Can this be attached? For the other case, it's not obvious that all islands should be oriented along the longest axis. For this model it makes sense. But it's not necessarily the most efficient way of packing, or the direction that a user would consider natural. I don't think either the new or old packing method was designed to do this, it was mostly a side effect where depending on the model it may or may not work out like that. The Pack Islands operator in the UV editor is the place where there is more control over the packing strategy. Using a different Rotation Method there seems like it orients the islands along the longest axis, but I think this is also somewhat accidental. Adding a rotation method that does this explicitly would be a good feature to add. It's not obvious to me that Smart UV Project should be changed to work like that, whatever strategy we use there will be suboptimal for some model. @ideasman42, do you have an opinion on the packing strategy for Smart UV Project?

Campbell Barton commented

2024-01-09 13:40:10 +01:00

Owner

Smart UV Project (the original Python version) intentionally aligned islands vertically, for wood-grain for e.g. tended to be aligned more usefully - in general, I'll check on adding support back.

Smart UV Project (the original Python version) intentionally aligned islands vertically, for wood-grain for e.g. tended to be aligned more usefully - in general, I'll check on adding support back.

Campbell Barton referenced this issue from a commit

2024-01-10 02:34:55 +01:00

UV: restore axis alignment support for Smart UV Project

Campbell Barton closed this issue

2024-01-10 02:34:57 +01:00

Blender Bot added

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labels 2024-01-10 02:34:58 +01:00

Hans Goudey added

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labels 2024-01-10 03:25:40 +01:00

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