Proportional Editing: 'Connected Only' option can cause distortions depending on topology #78752

New Issue

Diogo Valadares Reis dos Santos · 2020-07-09T03:32:54+02:00

Diogo Valadares Reis dos Santos commented

2020-07-09 03:32:54 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: AMD Radeon RX 5700 XT ATI Technologies Inc. 4.5.13587 Core Profile Context 20.4.2 26.20.15029.27017

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-07-04 15:31, hash: 464aaf2701
Worked: -

Short description of error
when using "connected only" depending of the topology of the mesh you get weird "lines" on the surface

Exact steps for others to reproduce the error

create a plane and subdivide it
in edit mode, grab the middle vertice and pull it up using proportional editing. You will notice that you get different results if "connected only" if active or not.

In the left you can see that its smooth while in the right its has this piramid shape

The same test but with the mesh triangulated

I don't know if this is intended but I think "connected only" was supposed to only make other meshs not get afected with the "proportional editing" and not change how it works in the mesh you want to edit.

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: AMD Radeon RX 5700 XT ATI Technologies Inc. 4.5.13587 Core Profile Context 20.4.2 26.20.15029.27017 **Blender Version** Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-07-04 15:31, hash: `464aaf2701` Worked: - **Short description of error** when using "connected only" depending of the topology of the mesh you get weird "lines" on the surface **Exact steps for others to reproduce the error** - create a plane and subdivide it - in edit mode, grab the middle vertice and pull it up using proportional editing. You will notice that you get different results if "connected only" if active or not. ![image.png](https://archive.blender.org/developer/F8679550/image.png) In the left you can see that its smooth while in the right its has this piramid shape The same test but with the mesh triangulated ![image.png](https://archive.blender.org/developer/F8679554/image.png) I don't know if this is intended but I think "connected only" was supposed to only make other meshs not get afected with the "proportional editing" and not change how it works in the mesh you want to edit.

Diogo Valadares Reis dos Santos commented

2020-07-09 03:32:54 +02:00

Added subscriber: @Diogo_Valadares

Philipp Oeser commented

2020-07-09 13:00:09 +02:00

Added subscribers: @brecht, @lichtwerk

Philipp Oeser commented

2020-07-09 13:00:09 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser commented

2020-07-09 13:00:09 +02:00

This has been reported before, see #43393 (proportional editing issue with "connected" mode), #53602 (Mesh - Proportional Editing (Connected) Bug), #35590 (Connected proportional editing gives unexpected results )

There was even a patch for this, see D2345: Proportional Editing Octangler Distortion, quoting @brecht from there:

In D2345 #54454, @brecht wrote:
But the real problem is that the way this distance is computed is not exact and influenced too much by the particular topology, and that's what should be fixed. In general the correct solution would be to use Geodesic distances (there are [many ]] https:*www.cs.cmu.edu/~kmcrane/Projects/GeodesicsInHeat/ [ http://i.cs.hku.hk/~xghan/Projects/VTP.htm | papers about this that tend to be quite complex), or there may be some simpler heuristics than work well enough to get a smoother distance here.

So while this has been turned down previously as not a bug, I see this as a Known Issue now [it is not really against blenders design - but it is uncertain if a dev will work on this anytime soon]

This has been reported before, see #43393 (proportional editing issue with "connected" mode), #53602 (Mesh - Proportional Editing (Connected) Bug), #35590 (Connected proportional editing gives unexpected results ) There was even a patch for this, see [D2345: Proportional Editing Octangler Distortion](https://archive.blender.org/developer/D2345), quoting @brecht from there: > In [D2345](https://archive.blender.org/developer/D2345)#54454, @brecht wrote: > But the real problem is that the way this distance is computed is not exact and influenced too much by the particular topology, and that's what should be fixed. In general the correct solution would be to use Geodesic distances (there are [many ]] [[ https:*www.cs.cmu.edu/~kmcrane/Projects/GeodesicsInHeat/ | research ]] [[ http://i.cs.hku.hk/~xghan/Projects/VTP.htm | papers ](http:*hhoppe.com/proj/geodesics/) about this that tend to be quite complex), or there may be some simpler heuristics than work well enough to get a smoother distance here. So while this has been turned down previously as not a bug, I see this as a `Known Issue` now [it is not really against blenders design - but it is uncertain if a dev will work on this anytime soon]

Philipp Oeser changed title from ~~Connected only proportional editing bug~~ to Proportional Editing: 'Connected Only' option can cause distortions depending on topology

2020-07-09 13:02:55 +02:00

Pablo Dobarro commented

2020-07-09 18:49:38 +02:00

Added subscriber: @PabloDobarro

Pablo Dobarro commented

2020-07-09 18:49:38 +02:00

This is the same issues this patch D7059 has, and this is why it is still not merged. I investigated this for a while and I'm still not sure if this is something that can be computed in real time for any type of mesh. I guess the algorithm can be improved, but I would not expect this to be artifact free.

This is the same issues this patch [D7059](https://archive.blender.org/developer/D7059) has, and this is why it is still not merged. I investigated this for a while and I'm still not sure if this is something that can be computed in real time for any type of mesh. I guess the algorithm can be improved, but I would not expect this to be artifact free.

blender-admin commented

2020-12-31 07:49:19 +01:00

This issue was referenced by 21b9231d7f

This issue was referenced by 21b9231d7f5a248027c32dcc7daab3318390c20f

Brecht Van Lommel commented

2021-01-13 18:25:09 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Brecht Van Lommel closed this issue

2021-01-13 18:25:09 +01:00

Brecht Van Lommel self-assigned this 2021-01-13 18:25:09 +01:00

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Proportional Editing: 'Connected Only' option can cause distortions depending on topology #78752