Edit-mesh separate by loose parts stuck indefinitely #70864

New Issue

Daniel Salazar · 2019-10-16T04:55:17+02:00

Daniel Salazar commented

2019-10-16 04:55:17 +02:00

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 1080 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48

Blender Version
Broken: version: 2.82 (sub 0), branch: master, commit date: 2019-10-14 16:48, hash: 519891c669

Short description of error
The separate by loose parts tool hangs on large meshes.

Yes it's a fairly large mesh, but tools like select linked or even separate by selection do not have much problem with it. However separate by loose parts takes (forever?) I had to close Blender after 3 hours.

Exact steps for others to reproduce the error
Separate.blend
Enter edit mode
Press P
Separate by Loose Parts

Automated test:

blender Separate.blend -b --python-expr "import bpy, time; bpy.ops.object.editmode_toggle(); t = time.time(); print('Objects:', len(bpy.data.objects)); bpy.ops.mesh.separate(type='LOOSE'); print('Seconds:', time.time() - t, 'Objects:', len(bpy.data.objects))"

**System Information** Operating system: Windows-10-10.0.18362 64 Bits Graphics card: GeForce GTX 1080 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48 **Blender Version** Broken: version: 2.82 (sub 0), branch: master, commit date: 2019-10-14 16:48, hash: `519891c669` **Short description of error** The separate by loose parts tool hangs on large meshes. Yes it's a fairly large mesh, but tools like select linked or even separate by selection do not have much problem with it. However separate by loose parts takes (forever?) I had to close Blender after 3 hours. **Exact steps for others to reproduce the error** [Separate.blend](https://archive.blender.org/developer/F7824377/Separate.blend) Enter edit mode Press P Separate by Loose Parts ---- Automated test: ``` blender Separate.blend -b --python-expr "import bpy, time; bpy.ops.object.editmode_toggle(); t = time.time(); print('Objects:', len(bpy.data.objects)); bpy.ops.mesh.separate(type='LOOSE'); print('Seconds:', time.time() - t, 'Objects:', len(bpy.data.objects))" ```

Daniel Salazar commented

2019-10-16 04:55:17 +02:00

Added subscriber: @zanqdo

Campbell Barton changed title from ~~Separate by loose parts~~ to Unreasonably high memory usage with edit-mesh separate by loose parts

2019-10-16 04:58:36 +02:00

Campbell Barton commented

2019-10-16 07:33:24 +02:00

Added subscriber: @ideasman42

Campbell Barton commented

2019-10-16 07:33:24 +02:00

Note that this was discussed in blender.chat, this report has some differences to the issue discussed in chat (not sure if the issue is memory usage or just being slow).

This file has 110,512 isolated vertices, each is creating a new object.
Copying the geometry is inefficient too, although it's not the root-cause of the problem.

Firstly to avoid this issue you could delete all isolated vertices.

As for how Blender could handle this better, we could do a pass for isolated verts/edges/faces and split them into a single object.

There might be some cases existing behavior is preferred, so that could be an option (off by default).

Note that this was discussed in blender.chat, this report has some differences to the issue discussed in chat (not sure if the issue is memory usage or just being slow). This file has 110,512 isolated vertices, each is creating a new object. Copying the geometry is inefficient too, although it's not the root-cause of the problem. Firstly to avoid this issue you could delete all isolated vertices. As for how Blender could handle this better, we could do a pass for isolated verts/edges/faces and split them into a single object. There might be some cases existing behavior is preferred, so that could be an option (off by default).

Daniel Salazar changed title from ~~Unreasonably high memory usage with edit-mesh separate by loose parts~~ to Edit-mesh separate by loose parts stuck indefinately

2019-10-16 08:14:19 +02:00

Daniel Salazar changed title from ~~Edit-mesh separate by loose parts stuck indefinately~~ to Edit-mesh separate by loose parts stuck indefinitely

2019-10-16 08:14:51 +02:00

Daniel Salazar commented

2019-10-16 08:26:46 +02:00

You are right, it's the solo verts that are causing it to hang forever. After I removed them with a non manifold select operation it managed to separate quite quickly.

The problem with this is that lots of CAD files come with similar geometry so the operator just hangs for no apparent reason.

You are right, it's the solo verts that are causing it to hang forever. After I removed them with a non manifold select operation it managed to separate quite quickly. The problem with this is that lots of CAD files come with similar geometry so the operator just hangs for no apparent reason.

Campbell Barton commented

2019-10-16 08:30:42 +02:00

@zanqdo what do you think about the solution/workaround proposed above?

Daniel Salazar commented

2019-10-16 08:34:30 +02:00

Having all isolated vertices into a single object by default sounds perfectly reasonable. Considering the trouble of creating thousands of single vert objects.

Daniel Salazar commented

2019-10-16 09:19:03 +02:00

As mentioned on the chat. This would solve this test file but not a real use case where the mesh comes with thousands of valid parts (CAD Files). The split algorithm seems to be escalating really poorly until the point that you have to force quit Blender.

Campbell Barton commented

2019-10-16 11:52:24 +02:00

Something closer to the real test case would be useful to have (just randomize locations, it will work the same for our purposes).

blender-admin commented

2019-10-20 16:47:16 +02:00

This issue was referenced by 71538eaad6

This issue was referenced by 71538eaad66b0d2a532df4b1f82e983fb6aed088

Campbell Barton commented

2019-10-20 17:58:08 +02:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2019-10-20 17:58:08 +02:00

Campbell Barton self-assigned this 2019-10-20 17:58:08 +02:00

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Edit-mesh separate by loose parts stuck indefinitely #70864