Add Page on Non-Manifold Geometry #42900

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Greg Zaal · 2014-12-14T18:23:02+01:00

Greg Zaal commented

2014-12-14 18:23:02 +01:00

Non-manifold geometry is referred to in various places in the documentation, and even explained in more than one place. It would make sense if this was covered in the glossary, explaining everything that makes a mesh manifold/watertight and then simply link to that from other pages using:

:term:`manifold`

To get a list of docs referring to 'water tight' or 'manifold', just do grep -r -i -l 'manifold\|water*tight' manual/*

Non-manifold geometry is referred to in various places in the documentation, and even explained in more than one place. It would make sense if this was covered in the glossary, explaining everything that makes a mesh manifold/watertight and then simply link to that from other pages using: ``` :term:`manifold` ``` To get a list of docs referring to 'water tight' or 'manifold', just do `grep -r -i -l 'manifold\|water*tight' manual/*`

Greg Zaal commented

2014-12-14 18:23:02 +01:00

Changed status to: 'Open'

Greg Zaal commented

2014-12-14 18:23:02 +01:00

Added subscriber: @GregZaal

Campbell Barton commented

2014-12-15 15:16:29 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2014-12-15 15:16:29 +01:00

Should this section be in the glossary? (perhaps we should collect general terms & info there)

manual/glossary/index.rst

This means anywhere we want to reference it we can do for eg:

      Some tool needs :term:`Non Manifold` geometry.

Which will be a link to the glossary.

Should this section be in the glossary? (perhaps we should collect general terms & info there) `manual/glossary/index.rst` This means anywhere we want to reference it we can do for eg: ``` Some tool needs :term:`Non Manifold` geometry. ``` Which will be a link to the glossary.

Greg Zaal commented

2014-12-15 15:37:19 +01:00

%%%Yes the glossary is the perfect place I think. And :term:blah would be really handy.

%%%Yes the glossary is the perfect place I think. And :term:`blah` would be really handy.

Campbell Barton commented

2014-12-15 15:42:40 +01:00

We can already add glossary links (even if the content is missing).

See: https://developer.blender.org/diffusion/BM/browse/master/manual/glossary/index.rst (See lattice)

Note, content can be taken from here:
http://blender.stackexchange.com/questions/7910/what-is-non-manifold-geometry

@GregZaal, maybe worth updating original task

We can already add glossary links (even if the content is missing). See: https://developer.blender.org/diffusion/BM/browse/master/manual/glossary/index.rst (See lattice) Note, content can be taken from here: http://blender.stackexchange.com/questions/7910/what-is-non-manifold-geometry @GregZaal, maybe worth updating original task

Greg Zaal commented

2014-12-17 12:04:45 +01:00

Seems I cannot edit this task: http://i.imgur.com/uIoJuzd.png

Greg Zaal self-assigned this 2014-12-21 17:40:26 +01:00

Greg Zaal removed their assignment 2014-12-21 17:45:06 +01:00

Greg Zaal commented

2014-12-21 17:45:06 +01:00

Assigned to self temporarily to edit the task (Phab is weird)

Pep commented

2014-12-22 23:50:01 +01:00

Added subscriber: @pepribal

Pep commented

2014-12-22 23:50:01 +01:00

I can go for it. I think I'm getting the hang of it. If you agree, I can add definitions of "Manifold", "Non Manifold" and "Watertight" (or "Water tight"?). I'll try to update all references to these terms too throughout the manual. I don't know it I should/could assign the task to myself?

Pep was assigned by Greg Zaal

2014-12-23 10:51:15 +01:00

Greg Zaal commented

2014-12-23 10:51:15 +01:00

That'd be great, thanks!

Just add one new definition (Manifold) and mention in that section that 'non-manifold' is the reverse. "Water tight" is just a way to explain what manifold means.

As Campbell mentioned earlier, there's a pretty good explanation over on StackExchange: http://blender.stackexchange.com/questions/7910/what-is-non-manifold-geometry - you could summarize this, and perhaps even provide a link to that for more details.

I've assigned this task to you now. In future, you just need to change the 'action' above the comment area from "Comment" to "Reassign / Claim".

That'd be great, thanks! Just add one new definition (Manifold) and mention in that section that 'non-manifold' is the reverse. "Water tight" is just a way to explain what manifold means. As Campbell mentioned earlier, there's a pretty good explanation over on StackExchange: http://blender.stackexchange.com/questions/7910/what-is-non-manifold-geometry - you could summarize this, and perhaps even provide a link to that for more details. I've assigned this task to you now. In future, you just need to change the 'action' above the comment area from "Comment" to "Reassign / Claim".

Pep commented

2014-12-23 16:37:57 +01:00

Here is the finished patch:

Added Manifold and Non-Manifold terms in the glossary.
Updated the '3D View >> Select >> Non Manifold' menu entry (from a couple of places, as it is duplicated).
Added references to the new terms throughout the entire manual. Changed all 'watertight' references to 'manifold', as there is no glossary term for the first one.

I didn't include a link to mentioned article in StackExchange; though it was useful, I don't see it as a reference from the manual. However, it's a simple opinion, so feel free to add it.

Regards,

Pep.

patch.txt

Here is the finished patch: - Added Manifold and Non-Manifold terms in the glossary. - Updated the '3D View >> Select >> Non Manifold' menu entry (from a couple of places, as it is duplicated). - Added references to the new terms throughout the entire manual. Changed all 'watertight' references to 'manifold', as there is no glossary term for the first one. I didn't include a link to mentioned article in StackExchange; though it was useful, I don't see it as a reference from the manual. However, it's a simple opinion, so feel free to add it. Regards, Pep. [patch.txt](https://archive.blender.org/developer/F133276/patch.txt)

Campbell Barton commented

2014-12-24 05:18:18 +01:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2014-12-24 05:18:18 +01:00

Campbell Barton commented

2014-12-24 05:18:18 +01:00

Closed by commit rBM5a337ab5d500.

Campbell Barton commented

2014-12-24 05:22:30 +01:00

Thanks for the patch!

Committed, note: removed the * Adjoining faces with opposite normals. from the list, I don't think non-contiguous face normals (while it can cause problems),
really constitutes non-manifold geometry (if this is the case - do you have a reference?).

Also added some clarification to the examples of what is manifold.

Edit, also removed the key-bineing for select non-manifold.

I think we should have some policy on this,
Having key-bindings in our docs seems a bit error prone (since they change from time to time), if we only include menu references, users can see key bindings in the menus.

Thanks for the patch! Committed, note: removed the `* Adjoining faces with opposite normals.` from the list, I don't think non-contiguous face normals (while it can cause problems), really constitutes non-manifold geometry (if this is the case - do you have a reference?). Also added some clarification to the examples of what is manifold. Edit, also removed the key-bineing for select non-manifold. I think we should have some policy on this, Having key-bindings in our docs seems a bit error prone (since they change from time to time), if we only include menu references, users can see key bindings in the menus.

Pep commented

2014-12-24 06:46:44 +01:00

Ok, about not including key bindings.

Regarding adjoining faces with opposite normals, I strongly think it's a case of non-manifold geometry. If manifold geometry defines a closed volume, that volume has an inside, and an outside. Normals point outside. If normals of adjoining faces point in opposite directions, that doesn't define a volume anymore, so it's definitely non-manifold geometry, IMHO (perhaps not that humble ;).

You can see this link:
http://knowledge.autodesk.com/support/maya-lt/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/MayaLT/files/Polygons-overview-Twomanifold-vs--nonmanifold-polygonal-geometry-htm.html

But, most important, Blender really does treat two adjoining faces with opposite normals as non-manifold. If you select non manifold from the Select menu, you'll notice an option in the redo panel wich reads Non Contiguous, which is specific to this very case.

This I have explained in document /modeling/meshes/selecting/advanced too.

Anyway, if you think it's not a non-manifold case, perhaps it should be removed also from the redo panel.

Regards,

Pep.

Ok, about not including key bindings. Regarding **adjoining faces with opposite normals**, I strongly think it's a case of non-manifold geometry. If manifold geometry defines a closed volume, that volume has an inside, and an outside. Normals point outside. If normals of adjoining faces point in opposite directions, that doesn't define a volume anymore, so it's definitely non-manifold geometry, IMHO (perhaps not that humble ;). You can see this link: http://knowledge.autodesk.com/support/maya-lt/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/MayaLT/files/Polygons-overview-Twomanifold-vs--nonmanifold-polygonal-geometry-htm.html But, most important, **Blender really does treat two adjoining faces with opposite normals as non-manifold**. If you select non manifold from the Select menu, you'll notice an option in the redo panel wich reads `Non Contiguous`, which is specific to this very case. This I have explained in document `/modeling/meshes/selecting/advanced` too. Anyway, if you think it's not a non-manifold case, perhaps it should be removed also from the redo panel. Regards, Pep.

Campbell Barton commented

2014-12-26 03:41:32 +01:00

Added subscriber: @PeppeCirotti

Campbell Barton commented

2014-12-26 03:41:32 +01:00

@PeppeCirotti Ribal, in this case, Blender's select manifold tool should be changed.
(strictly speaking).

We could add an operator to select non-contiguous normals, or just keep the option where it is, but have it off by default.

@PeppeCirotti Ribal, in this case, Blender's select manifold tool should be changed. (strictly speaking). We could add an operator to select non-contiguous normals, or just keep the option where it is, but have it off by default.

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Add Page on Non-Manifold Geometry #42900