PYTHON: bpy_extras.mesh_utils.mesh_linked_uv_islands Creates Exception in EditMode #86484

New Issue

paul geraskin · 2021-03-11T09:25:14+01:00

paul geraskin commented

2021-03-11 09:25:14 +01:00

Blender Version
Broken: 2.92 official release

Short description of error
I tested bpy_extras.mesh_utils.mesh_linked_uv_islands function. It works nice in ObjectMode but it creates an error in EditMode. Is it a bug?
tmp1.blend

Exact steps for others to reproduce the error

Open my blend file
Go to EditMode
Run a script. There will be Exception

**Blender Version** Broken: 2.92 official release **Short description of error** I tested bpy_extras.mesh_utils.mesh_linked_uv_islands function. It works nice in ObjectMode but it creates an error in EditMode. Is it a bug? [tmp1.blend](https://archive.blender.org/developer/F9884598/tmp1.blend) ![image.png](https://archive.blender.org/developer/F9884599/image.png) ![image.png](https://archive.blender.org/developer/F9884602/image.png) **Exact steps for others to reproduce the error** - Open my blend file - Go to EditMode - Run a script. There will be Exception

paul geraskin commented

2021-03-11 09:25:14 +01:00

Added subscriber: @PaulGeraskin

Philipp Oeser commented

2021-03-11 10:34:16 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-03-11 10:34:16 +01:00

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

Philipp Oeser commented

2021-03-11 10:34:16 +01:00

Can confirm

Philipp Oeser commented

2021-03-11 11:25:26 +01:00

Sorry, forgot that this is a general case, the way the script accesses mesh data is not suited for editmode

https://docs.blender.org/api/master/bpy.types.Mesh.html

The mesh data is accessed in object mode and intended for compact storage, for more flexible mesh editing from python see bmesh

So, uv_layers is not available in editmode.

We could go through bmesh instead (then to be found in uv_layer = bm.loops.layers.uv.active) or switch to objectmode in this case (think this is what most scripts do?)

In any case, we should not throw an error.

Sorry, forgot that this is a general case, the way the script accesses mesh data is not suited for editmode https://docs.blender.org/api/master/bpy.types.Mesh.html > The mesh data is accessed in object mode and intended for compact storage, for more flexible mesh editing from python see bmesh So, `uv_layers` is not available in editmode. We could go through bmesh instead (then to be found in `uv_layer = bm.loops.layers.uv.active`) or switch to objectmode in this case (think this is what most scripts do?) In any case, we should not throw an error.

Philipp Oeser self-assigned this 2021-03-11 11:37:50 +01:00

Philipp Oeser commented

2021-03-11 12:56:54 +01:00

I have put up a patch preventing the error [and going through bmesh if in editmode].
I am unsure though if bmesh is allowed inside mesh_utils, so outcome might just be that mesh_linked_uv_islands will return an empty list instead.

But of course you will want to have this working in editmode, so for now you can also just do

is_editmode = (ob.mode == 'EDIT')
if is_editmode:
  bpy.ops.object.mode_set(mode='OBJECT', toggle=False)

do the call
       
if is_editmode:
  bpy.ops.object.mode_set(mode='EDIT', toggle=False)

I have put up a patch preventing the error [and going through bmesh if in editmode]. I am unsure though if `bmesh` is allowed inside `mesh_utils`, so outcome might just be that `mesh_linked_uv_islands` will return an empty list instead. But of course you will want to have this working in editmode, so for now you can also just do ``` is_editmode = (ob.mode == 'EDIT') if is_editmode: bpy.ops.object.mode_set(mode='OBJECT', toggle=False) do the call if is_editmode: bpy.ops.object.mode_set(mode='EDIT', toggle=False) ```

paul geraskin commented

2021-03-11 12:58:42 +01:00

Thank you! I'll write a small comment there.

Philipp Oeser removed their assignment 2022-01-18 21:03:54 +01:00

Philipp Oeser commented

2022-01-18 21:03:54 +01:00

Will have to concentrate on triaging for a while (and step down).