Mesh. Skin modifier shows nothing in viewport, when mesh do not have root. #85461

New Issue

Vyacheslav Kobozev · 2021-02-08T09:28:52+01:00

2021-02-08 09:28:52 +01:00

System Information
Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-02-04 00:22, hash: d30320b4f5
broken 2.83.9

Short description of error
Create edge,
Subdivide it few times
Set skin modifier
Select part of this mesh
separate by selection

Second part do not have rood and any appearance in viewport.
I expect to see original mesh, if skin modifier can`t produce anything.

untitled.blend

2021-02-08_11-20-53.mp4

**System Information** Operating system: Windows-7-6.1.7601-SP1 64 Bits Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71 **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-02-04 00:22, hash: `d30320b4f5` broken 2.83.9 **Short description of error** Create edge, Subdivide it few times Set skin modifier Select part of this mesh separate by selection Second part do not have rood and any appearance in viewport. I expect to see original mesh, if skin modifier can`t produce anything. [untitled.blend](https://archive.blender.org/developer/F9721129/untitled.blend) [2021-02-08_11-20-53.mp4](https://archive.blender.org/developer/F9721207/2021-02-08_11-20-53.mp4)

Vyacheslav Kobozev commented

2021-02-08 09:28:52 +01:00

Added subscriber: @Vyach

Falk David commented

2021-02-08 12:10:30 +01:00

Added subscriber: @filedescriptor

Falk David commented

2021-02-08 12:10:30 +01:00

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

Falk David commented

2021-02-08 12:10:30 +01:00

I can reproduce this issue on 2.93.0 Alpha, branch: master, commit date: 2021-02-08 10:36, hash: ecfd5360a1. The warning is displayed in the modifier and in the console.

Not sure if there is an easy way of solving this, since if there was, the warning would probably not just be logged but fixed? My guess is that there is no good way of choosing a root automatically.

I can reproduce this issue on 2.93.0 Alpha, branch: master, commit date: 2021-02-08 10:36, hash: `ecfd5360a1`. The warning is displayed in the modifier and in the console. ```ERROR (bke.modifier): source/blender/blenkernel/intern/modifier.c:457 BKE_modifier_set_error: Object: "Plane.001", Modifier: "Skin", No valid root vertex found (you need one per mesh island you want to skin) ``` Not sure if there is an easy way of solving this, since if there was, the warning would probably not just be logged but fixed? My guess is that there is no good way of choosing a root automatically.

Philipp Oeser commented

2021-02-09 08:59:39 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-02-09 08:59:39 +01:00

Changed status from 'Confirmed' to: 'Archived'

Philipp Oeser closed this issue

2021-02-09 08:59:39 +01:00

Philipp Oeser commented

2021-02-09 08:59:39 +01:00

There is no automatic assignment of a "new" root vertex if the "old" root vertex was deleted [I think this is the cause for running into this situation?].
I am not even sure if blender should assign a "new" root in this case? (choice would be kind of arbitrary).

Like @filedescriptor said, there is a clear warning in the modifier UI:

This might have room for improvement, but would not be considered a bug atm.
Thx reporting (@Vyach : your reports are always very much appreciated!), but in this case: will have to close.

There is no automatic assignment of a "new" root vertex if the "old" root vertex was deleted [I think this is the cause for running into this situation?]. I am not even sure if blender should assign a "new" root in this case? (choice would be kind of arbitrary). Like @filedescriptor said, there is a clear warning in the modifier UI: ![image.png](https://archive.blender.org/developer/F9744373/image.png) This *might* have room for improvement, but would not be considered a bug atm. Thx reporting (@Vyach : your reports are always very much appreciated!), but in this case: will have to close.

Vyacheslav Kobozev commented

2021-02-09 18:22:02 +01:00

@lichtwerk I do not expect authomatic root assignment here (but it will be better to mark roon on the ripped vertex)

I expect, that my mesh will not disappear in viewport, and will not produce glitches, so I can select it in viewport and fix it.
Otherwise i should dig in outliner hierarchy, and select mesh only there.

Please reopen.

@lichtwerk I do not expect authomatic root assignment here (but it will be better to mark roon on the ripped vertex) I expect, that my mesh will not disappear in viewport, and will not produce glitches, so I can select it in viewport and fix it. Otherwise i should dig in outliner hierarchy, and select mesh only there. Please reopen.

Philipp Oeser commented

2021-02-09 18:30:51 +01:00

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

Philipp Oeser reopened this issue

2021-02-09 18:30:51 +01:00

Philipp Oeser commented

2021-02-09 18:30:51 +01:00

I expect, that my mesh will not disappear in viewport

Ah, that, will check again

> I expect, that my mesh will not disappear in viewport Ah, that, will check again

Philipp Oeser self-assigned this 2021-02-09 18:49:19 +01:00

Vyacheslav Kobozev commented

2021-02-09 18:57:37 +01:00

@lichtwerk yup, attached file have invisible mesh.

Germano Cavalcante commented

2021-02-11 15:45:54 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-02-11 15:45:54 +01:00

As the generated mesh is composed of faces concentrated in a single line, the triangles of these faces have no area and therefore cannot be rasterized for visualization. This is a known limitation.

However, the fact that the mesh is not visible even if selected can be considered a regression compared to blender 2.79 (that displayed an outline).

This however deserves its own report (without necessarily mentioning modifiers).

As the generated mesh is composed of faces concentrated in a single line, the triangles of these faces have no area and therefore cannot be rasterized for visualization. This is a known limitation. However, the fact that the mesh is not visible even if selected can be considered a regression compared to blender 2.79 (that displayed an outline). This however deserves its own report (without necessarily mentioning modifiers).

Philipp Oeser commented

2021-02-11 16:52:38 +01:00

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

Philipp Oeser closed this issue

2021-02-11 16:52:38 +01:00

Philipp Oeser commented

2021-02-11 16:52:38 +01:00

In #85461#1110542, @mano-wii wrote:
As the generated mesh is composed of triangles concentrated in a single line, these triangles have no area and therefore cannot be rasterized for visualization. This is a known limitation.

Noticed this, too.
First I thought the modifier would spit out an empty mesh (this could have been detected easily and in that case we could have returned the original input mesh).
Also, single nodes without a root are valid for single vertices (spits out boxes/cubes then).

However, the fact that the mesh is not visible even if selected can be considered a regression compared to blender 2.79 (that displayed an outline).

This however deserves its own report (without necessarily mentioning modifiers).

OKi, then lets close this and I'll try to make a report for zero-area triangle meshes lacking an outline.

> In #85461#1110542, @mano-wii wrote: > As the generated mesh is composed of triangles concentrated in a single line, these triangles have no area and therefore cannot be rasterized for visualization. This is a known limitation. Noticed this, too. First I thought the modifier would spit out an empty mesh (this could have been detected easily and in that case we could have returned the original input mesh). Also, single nodes without a root are valid for single vertices (spits out boxes/cubes then). > However, the fact that the mesh is not visible even if selected can be considered a regression compared to blender 2.79 (that displayed an outline). > > This however deserves its own report (without necessarily mentioning modifiers). OKi, then lets close this and I'll try to make a report for zero-area triangle meshes lacking an outline.

Philipp Oeser commented

2021-02-11 17:05:33 +01:00

New outline task is #85557 (Zero area meshes lacking an outline (even if selected))

Vyacheslav Kobozev commented

2021-02-12 15:09:59 +01:00

@mano-wii @lichtwerk
thanks!

@mano-wii @lichtwerk thanks!

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Mesh. Skin modifier shows nothing in viewport, when mesh do not have root. #85461