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Skin Modifier does not return to normal after mesh reduced to a single vertex
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Description

System Information
OS X 10.6.8
NVIDIA GeForce 320M

Blender Version
Broken: 2.76 RC3 fb76f6d
Worked: unknown

Short description of error
If an object has a Skin Modifier on it, the modifier stops working in the event that the mesh is reduced to a single vertex.
While this isn't likely to go noticed by a lot of people, it is inconsistent with expected behavior and may cause confusion.

Exact steps for others to reproduce the error

  1. Create a simple mesh object like a plane
  2. Add a Skin Modifier to the mesh object
  3. In Edit Mode delete all but one vertex from the mesh
  4. Extrude the remaining vertex into an edge and notice it is not "skinned" In order to remedy this, the Modifier must be deleted and a new one added from scratch.

Details

Type
Bug

Event Timeline

Seth L. (quantumanomaly) raised the priority of this task from to Needs Triage by Developer.
Seth L. (quantumanomaly) updated the task description. (Show Details)
Seth L. (quantumanomaly) set Type to Bug.

Additional info:

When I submitted this I was on RC3. I've since upgraded to 2.76 and the bug is still present.

It seems not to always happen if you stay in Vertex Select Mode. However, if you switch to Edge Select Mode at any time while having only one vert it seems to happen every time.

Bastien Montagne (mont29) claimed this task.

Thanks for the report, but no bug here really, thing is, outside of loose vertices, you need a 'root' vert for this modifier to work (in edit mode, select one vert and hit “Mark Root” in modifier panel). Root vert is circled by a dashed line in edit mode, so you can also delete all verts but two (defining an edge) and, as long as root one is deleted, you'll have no skinning either.

I see! It's all clear now. Thanks for explaining!

Just an idea for the future - how about if an alert message in the modifier were displayed when no root vertex is present?

Regarding my last comment, I can see now that it is possible to have a mesh with multiple pieces of disconnected geometry, some having a root vert (and therefor skinned) and others not. So even if a root vert is present on some pieces, if a root vert is not present on each piece the object will not be skinned entirely. So if an alert message were to be added it should probably be worded to include this idea.

Done, thanks for suggestion.