Smooth Vertices (Laplacian) produces NaN coordinates for loose vertices and edges #89214

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Fen · 2021-06-16T21:08:35+02:00

Fen commented

2021-06-16 21:08:35 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 446.14

Blender Version
Broken: version: 3.0.0 Alpha. Commit hash: 247abdbf41
Worked: Broken back to 2.65, which is around when the operator was introduced

I was missing build info, so I filled the above in manually

Short description of error
The Smooth Vertices (Laplacian) (bpy.ops.mesh.vertices_smooth_laplacian()) will generate NaN coordinates for any vertex or edge that is not part of a face.

This only happens if at least one face exists. A mesh with no faces does not trigger this bug.

Exact steps for others to reproduce the error

Delete the starting objects
Create a plane
Go into edge-select mode and duplicate one of the plane's edges. Move it to the side a bit.
Run the Smooth Vertices (Laplacian) operator. The edge should disappear, and its Transform should now be full of nans
Go into vertex-select mode and extrude one of the plane's vertices
Run the operator again. The vertex should disappear, with the same nan result
Go into face-select mode and select the plane's face.
Duplicate the face and move it to the side
Delete only faces
Run the operator again. The edges should all disappear

A file with everything set up is attached:

smooth-laplacian-nan.blend

I haven't observed this with the Smooth Laplacian modifier.

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 446.14 **Blender Version** Broken: version: 3.0.0 Alpha. Commit hash: 247abdbf4148843daf469285a6a63ab9cd0aeef9 Worked: Broken back to 2.65, which is around when the operator was introduced I was missing build info, so I filled the above in manually **Short description of error** The *Smooth Vertices (Laplacian)* (`bpy.ops.mesh.vertices_smooth_laplacian()`) will generate NaN coordinates for any vertex or edge that is not part of a face. This only happens if at least one face exists. A mesh with no faces does not trigger this bug. **Exact steps for others to reproduce the error** 1. Delete the starting objects 2. Create a plane 3. Go into edge-select mode and duplicate one of the plane's edges. Move it to the side a bit. 4. Run the *Smooth Vertices (Laplacian)* operator. The edge should disappear, and its Transform should now be full of nans 5. Go into vertex-select mode and extrude one of the plane's vertices 6. Run the operator again. The vertex should disappear, with the same nan result 7. Go into face-select mode and select the plane's face. 8. Duplicate the face and move it to the side 9. Delete only faces 10. Run the operator again. The edges should all disappear A file with everything set up is attached: [smooth-laplacian-nan.blend](https://archive.blender.org/developer/F10175797/smooth-laplacian-nan.blend) I haven't observed this with the *Smooth Laplacian* modifier.

Fen commented

2021-06-16 21:08:35 +02:00

Added subscriber: @chemicalcrux

Evan Wilson commented

2021-06-17 02:31:10 +02:00

Added subscriber: @EAW

Evan Wilson commented

2021-06-17 02:31:10 +02:00

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

Evan Wilson commented

2021-06-17 02:31:10 +02:00

I can confirm using Alpha 3.0.0 845f4cebad

Tested using:
OS: Windows-10-10.0.19041.630-SP0 64 Bits
GPU: GeForce GTX 470/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.35

I can confirm using Alpha 3.0.0 845f4cebadc8 --- Tested using: OS: Windows-10-10.0.19041.630-SP0 64 Bits GPU: GeForce GTX 470/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.35

Germano Cavalcante commented

2021-06-22 16:17:25 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-06-22 16:17:25 +02:00

NaN coordinates indicate corrupted mesh that can trigger serious problems.
So I'm setting this report as having high priority.

NaN coordinates indicate corrupted mesh that can trigger serious problems. So I'm setting this report as having high priority.

Fen commented

2021-06-23 19:21:31 +02:00

Yes, I was getting a lot of crashes from this. Many operators will crash Blender if given NaN coordinates.

Unfortunately, I don't understand the logic at all, so I can't help much :p . I do see that the operator and the modifier use different validate_solution functions...perhaps the modifier's does something that the operator's does not?

Yes, I was getting a *lot* of crashes from this. Many operators will crash Blender if given NaN coordinates. Unfortunately, I don't understand the logic at all, so I can't help much :p . I do see that the operator and the modifier use different `validate_solution` functions...perhaps the modifier's does something that the operator's does not?

AJP commented

2021-06-29 09:05:26 +02:00

Added subscriber: @astronotter-4

AJP self-assigned this 2021-06-29 09:05:26 +02:00

AJP commented

2021-06-29 09:05:26 +02:00

I've done some digging and found the cause of the NaNs to be the initial linear system becoming filled with Infs, which in turn is because the 'areas' associated with loose edges are 0. There seem to be flags to detect 0 area already, but I believe they don't account for the system itself filling up with Inf and then giving an incorrect result.

AJP commented

2021-06-29 09:11:53 +02:00

This comment was removed by @astronotter-4

*This comment was removed by @astronotter-4*

blender-admin commented

2021-08-05 12:41:23 +02:00

This issue was referenced by ed9759349b

This issue was referenced by ed9759349b3da090d22bd34bc066b72025679dc4

Campbell Barton commented

2021-08-05 12:53:08 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Campbell Barton closed this issue

2021-08-05 12:53:08 +02:00

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Smooth Vertices (Laplacian) produces NaN coordinates for loose vertices and edges #89214