possible bug in mesh unwrapping #34216

New Issue

CJ L · 2013-02-12T19:35:43+01:00

CJ L commented

2013-02-12 19:35:43 +01:00

%%%--- Blender version with error, and version that worked ---
all 2.5+ versions up to the current 2.66 RC

- Short description of error ---

It's about unwrapping 2 faces connected to 2 other already unvrapped faces that have pinned UVs.
The 2 faces to be unwrapped come in UV window in the wrong direction. Flipping normals of all faces
and unwrapping again gives UVs unwrapped in the right direction. After a small discussion with
deeper explainations and pictures to see things on the blenderartists forum it came that this could be a bug.
It's the reason why i post this bug report.
The forum discussion can be found at:
http://blenderartists.org/forum/showthread.php?281403-UV-mapping-bug-or-(-boring-)-feature

- Steps for others to reproduce the error (preferably based on attached .blend file) ---

Grab and unzip the blend file.
go in edit mode
select all faces
hit U-KEY and choose unwrap

thanks a lot !
regards.

%%%

%%%--- Blender version with error, and version that worked --- all 2.5+ versions up to the current 2.66 RC - Short description of error --- It's about unwrapping 2 faces connected to 2 other already unvrapped faces that have pinned UVs. The 2 faces to be unwrapped come in UV window in the wrong direction. Flipping normals of all faces and unwrapping again gives UVs unwrapped in the right direction. After a small discussion with deeper explainations and pictures to see things on the blenderartists forum it came that this could be a bug. It's the reason why i post this bug report. The forum discussion can be found at: http://blenderartists.org/forum/showthread.php?281403-UV-mapping-bug-or-(-boring-)-feature - Steps for others to reproduce the error (preferably based on attached .blend file) --- Grab and unzip the blend file. go in edit mode select all faces hit U-KEY and choose unwrap thanks a lot ! regards. %%%

CJ L commented

2013-02-12 19:35:43 +01:00

Changed status to: 'Open'

Brecht Van Lommel commented

2013-02-13 11:11:06 +01:00

%%%What's happening is that the Unwrap tool will unwrap faces with their normals pointing up. In this case you have pinned some faces with their normals pointing down. Probably the tool could be smarter here by detecting this and then unwrapping all the other faces with the normal pointing down.

If this is a face that you will see from two sides there is no preferred direction, but note that if not, any image texture applied to this face will render flipped because of this.%%%

%%%What's happening is that the Unwrap tool will unwrap faces with their normals pointing up. In this case you have pinned some faces with their normals pointing down. Probably the tool could be smarter here by detecting this and then unwrapping all the other faces with the normal pointing down. If this is a face that you will see from two sides there is no preferred direction, but note that if not, any image texture applied to this face will render flipped because of this.%%%

Brecht Van Lommel commented

2013-02-13 11:37:38 +01:00

%%%Fix committed now, which will make this case work at least. In general this can still be a bit fuzzy and not so easy for the unwrapper to figure out the up/down pin direction, but it should be improved now.%%%

Brecht Van Lommel commented

2013-02-13 11:37:38 +01:00

Changed status from 'Open' to: 'Resolved'

Brecht Van Lommel closed this issue

2013-02-13 11:37:38 +01:00

CJ L commented

2013-02-13 11:46:37 +01:00

%%%Hi brecht.
Thanks a lot for your answer and explanation.

Then what i understand is that it's not a bug ( i was not sure though ) but a correct behaviour that is for my particular case very unconvenient to me.

Would be neat the unwrap tool were this smarter ;) however i can imagine this could be some headache to make the code decide what is the solution the user expects...
Therefore what do you think about setting up an option in the Tools dock that you could call 'consider flipped normals for unwrap' that would when ticked, temporarily flip the normals of the selected faces for the unwrap process ?

This should avoid complicated estimations in the code to guess what the user wants, and will let the user decide for himself.

What do you think about this ?

regards.%%%

%%%Hi brecht. Thanks a lot for your answer and explanation. Then what i understand is that it's not a bug ( i was not sure though ) but a correct behaviour that is for my particular case very unconvenient to me. Would be neat the unwrap tool were this smarter ;) however i can imagine this could be some headache to make the code decide what is the solution the user expects... Therefore what do you think about setting up an option in the Tools dock that you could call 'consider flipped normals for unwrap' that would when ticked, temporarily flip the normals of the selected faces for the unwrap process ? This should avoid complicated estimations in the code to guess what the user wants, and will let the user decide for himself. What do you think about this ? regards.%%%

CJ L commented

2013-02-13 11:51:31 +01:00

%%%Sorry, you posted before me ;)
Yes i believe this is not an easy fix. And this is the reason why i talked about a simple & efficient solution: the checkbox called 'unwrap with flipped normals'.

Mebe codes have more important things to do than improving this, and i guess that time to spend on this will be shorter if a button to let user decide is implemented
( imho it's a perfect solution to the problem ) instead of a guessing algorythm that might not be able to handle all the possible cases ;-)
regards.%%%

%%%Sorry, you posted before me ;) Yes i believe this is not an easy fix. And this is the reason why i talked about a simple & efficient solution: the checkbox called 'unwrap with flipped normals'. Mebe codes have more important things to do than improving this, and i guess that time to spend on this will be shorter if a button to let user decide is implemented ( imho it's a perfect solution to the problem ) instead of a guessing algorythm that might not be able to handle all the possible cases ;-) regards.%%%

CJ L commented

2013-02-15 16:54:25 +01:00

%%%Hi Brecht.

Sorry to ask stoopid questions but...
When you say: fix commited now, what does it mean ? ( am sorry i'm not used on collaborative dev methods )

Is there a blender version ( mebe the current 2.66RC ? ) that would contain a fix for the problem ?

Thanks for your answer :)

regards.%%%

%%%Hi Brecht. Sorry to ask stoopid questions but... When you say: fix commited now, what does it mean ? ( am sorry i'm not used on collaborative dev methods ) Is there a blender version ( mebe the current 2.66RC ? ) that would contain a fix for the problem ? Thanks for your answer :) regards.%%%

Brecht Van Lommel commented

2013-02-15 17:30:19 +01:00

%%%Nightly builds should always have the fix the next day:
http://builder.blender.org/download/

The 2.66 RC has it as well since it was made a few hours after I did this fix.%%%

%%%Nightly builds should always have the fix the next day: http://builder.blender.org/download/ The 2.66 RC has it as well since it was made a few hours after I did this fix.%%%

CJ L commented

2013-02-17 10:15:39 +01:00

%%%Thanks a lot ! i gonna give it a try ;)
%%%

%%%Thanks a lot ! i gonna give it a try ;) %%%

CJ L commented

2013-02-17 20:18:08 +01:00

%%%well well :)

what you did ( i confess i'm stunned ! you were that damn fast to fix this ! ) looks pretty good.
It works as expected in the blend i submitted, and gives the same result on whatever normals are ( in or out ).
I gonna dig a bit though and still have some few hundreds of faces to unwrap this way on my model.
I'll poste there if i find some issues :)

thanks again Brecht !

have nice blends and nice codings !
regards.%%%

%%%well well :) what you did ( i confess i'm stunned ! you were that damn fast to fix this ! ) looks pretty good. It works as expected in the blend i submitted, and gives the same result on whatever normals are ( in or out ). I gonna dig a bit though and still have some few hundreds of faces to unwrap this way on my model. I'll poste there if i find some issues :) thanks again Brecht ! have nice blends and nice codings ! regards.%%%

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

possible bug in mesh unwrapping #34216