Solidify Modifier wrong solidification normals in some cases #106741

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opened 2023-04-09 16:36:57 +02:00 by Pierre-Samuel-GREAU-HAMARD · 16 comments

Pierre-Samuel-GREAU-HAMARD commented

2023-04-09 16:36:57 +02:00

System Information
Operating system: Windows 11
Graphics card: ATX4000

Blender Version
Broken: 3.5.0

Short description of error
In some corner cases, the Solidify modifier uses wrong solidification normals.

Exact steps for others to reproduce the error
With the "Faces linked only by one vertex.obj" object, where some faces are sharing only one vertex and no edge, the solidification behaves as if ignoring that shared vertex.

With the "Triangulated mesh wrong solidification.obj" object the vertex in coordinates (-1, 1, -1) does not solidify properly, while the exact same mesh, but not triangulated ("Triangulated mesh right solidification.obj" object) solidifies right.

**System Information** Operating system: Windows 11 Graphics card: ATX4000 **Blender Version** Broken: 3.5.0 **Short description of error** In some corner cases, the Solidify modifier uses wrong solidification normals. **Exact steps for others to reproduce the error** With the "Faces linked only by one vertex.obj" object, where some faces are sharing only one vertex and no edge, the solidification behaves as if ignoring that shared vertex. With the "Triangulated mesh wrong solidification.obj" object the vertex in coordinates (-1, 1, -1) does not solidify properly, while the exact same mesh, but not triangulated ("Triangulated mesh right solidification.obj" object) solidifies right.

Triangulated mesh wrong solidification.obj

2.1 KiB

Faces linked only by one vertex.obj

2.0 KiB

Triangulated mesh right solidification.obj

1.8 KiB

Pierre-Samuel-GREAU-HAMARD added the

labels 2023-04-09 16:36:58 +02:00

Pratik Borhade commented

2023-04-10 06:41:46 +02:00

Member

Hi, thanks for the report. I'm unable to confirm the second case " vertex in coordinates (-1, 1, -1) does not solidify properly". Do I need to add solidify modifier on it after importing?

Hi, thanks for the report. I'm unable to confirm the second case " vertex in coordinates (-1, 1, -1) does not solidify properly". Do I need to add solidify modifier on it after importing?

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Pierre-Samuel-GREAU-HAMARD commented

2023-04-13 11:00:28 +02:00

Author

In both cases, I only provided the objects, you have to add a Solidify modifier on it, complex mode to see the problem.

In both cases, I only provided the objects, you have to add a Solidify modifier on it, complex mode to see the problem.

Iliya Katushenock added the

labels 2023-04-13 16:58:17 +02:00

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labels 2023-04-16 06:18:44 +02:00

Philipp Oeser commented

2023-04-18 15:50:40 +02:00

Member

Sorry, I think I dont properly understand the issue.

These are the areas in question, I imported the good and the bad OBJ, both objects have their solidify modifiers applied, the "bad" / triangulated OBJ has it tris removed again to see better.

Now these dont actually look to different for me?

Could you possibly elaborate what "does not solidify properly" means?
(screenshots might help here)

Sorry, I think I dont properly understand the issue. ![image](/attachments/ad8cfe5f-7092-4813-a2ec-f44845490a4c) These are the areas in question, I imported the good and the bad OBJ, both objects have their solidify modifiers applied, the "bad" / triangulated OBJ has it tris removed again to see better. Now these dont actually look to different for me? Could you possibly elaborate what "does not solidify properly" means? (screenshots might help here)

207 KiB

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labels 2023-04-18 15:50:55 +02:00

Pierre-Samuel-GREAU-HAMARD commented

2023-04-18 18:00:46 +02:00

Author

Hmm, I get results different from yours, in both cases. Attached are the right solidification and the wrong one, after limited dissolve (5°) for the triangulated mesh.

Hmm, I get results different from yours, in both cases. Attached are the right solidification and the wrong one, after limited dissolve (5°) for the triangulated mesh.

Right solidification.png

1.5 MiB

Wrong solidification.png

1.5 MiB

Right solidification.png

Wrong solidification.png

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Iliya Katushenock commented

2023-06-21 15:13:20 +02:00

Member

Hi, @Pierre-Samuel-GREAU-HAMARD can you reproduce this in 3.6, 4.0?

Hi, @Pierre-Samuel-GREAU-HAMARD can you reproduce this in 3.6, 4.0?

Pierre-Samuel-GREAU-HAMARD commented

2023-06-21 16:13:06 +02:00

Author

Hello,
I confirm that the issue remains exactly the same in 3.6 and 4.0.

Hello, I confirm that the issue remains exactly the same in 3.6 and 4.0.

Iliya Katushenock commented

2023-06-25 15:21:13 +02:00

Member

Can you share blend file with this bug? (I can not reproduce from scratch and attached obj. models).

Can you share blend file with this bug? (I can not reproduce from scratch and attached obj. models).

Pierre-Samuel-GREAU-HAMARD commented

2023-06-26 09:55:04 +02:00

Author

Ok, here are the blend files with the wrong solidification for triangulated mesh and faces connected by only one vertex.

Ok, here are the blend files with the wrong solidification for triangulated mesh and faces connected by only one vertex.

Triangulation wrong solidification.blend

852 KiB

Faces linked by only one vertex wrong solidification.blend

850 KiB

Iliya Katushenock commented

2023-06-26 15:00:58 +02:00

Member

@Pierre-Samuel-GREAU-HAMARD Thanks, still have some detection problems. More precisely, I see your result, but I can't reproduce it. Can you make the same file, but it must have a model without a modifier (apply a modifier) and with a modifier?

@Pierre-Samuel-GREAU-HAMARD Thanks, still have some detection problems. More precisely, I see your result, but I can't reproduce it. Can you make the same file, but it must have a model without a modifier (apply a modifier) and with a modifier?

Pierre-Samuel-GREAU-HAMARD commented

2023-06-26 16:01:30 +02:00

Author

Here are the same two files, but I added an other copy of the models with the Solidify modifier not applied.

Here are the same two files, but I added an other copy of the models with the Solidify modifier not applied.

Triangulation wrong solidification.blend

857 KiB

Faces linked by only one vertex wrong solidification.blend

854 KiB

Iliya Katushenock commented

2023-06-26 16:08:03 +02:00

Member

Thanks. Now i see. And now i not sure is this can be work correct, there is bad normals as i can see...

Thanks. Now i see. And now i not sure is this can be work correct, there is bad normals as i can see...

Pierre-Samuel-GREAU-HAMARD commented

2023-06-26 16:27:58 +02:00

Author

Solidification is correct without triangulation, so it means the triangulation process creates the problem. And for the one vertex contact only, it is really a corner case I tested while designing an add-on, and found that the solidification cannot handle it properly.

Solidification is correct without triangulation, so it means the triangulation process creates the problem. And for the one vertex contact only, it is really a corner case I tested while designing an add-on, and found that the solidification cannot handle it properly.

Philipp Oeser commented

2024-04-19 14:45:46 +02:00

Member

@Pierre-Samuel-GREAU-HAMARD : sorry this has been lying around for so long.

I can see the issue in the file from #106741 (comment)
However, the model has inconsistent normals :

Still unable to repro with the OBJs from the first comment, both have inconsistent normals

and both seem to have the "problem" of solidifying in the "wrong" direction where the normals point inside (solidify tries to go to the outside `then)

So it seems this does not really have to do with the fact of triangulation?

In order to "fix" this, you can go into editmode, select everything and do Mesh > Normals > Recalculate Outside, does this give the expected results for you?

@Pierre-Samuel-GREAU-HAMARD : sorry this has been lying around for so long. I can see the issue in the file from https://projects.blender.org/blender/blender/issues/106741#issuecomment-966830 However, the model has inconsistent normals : ![image](/attachments/bc331ea7-5d8c-432d-9bff-aedb109db6cd) Still unable to repro with the OBJs from the first comment, both have inconsistent normals ![image](/attachments/3aed6eb4-c1c7-4f81-97ae-7f7a4e4e4bcb) and both seem to have the "problem" of solidifying in the "wrong" direction where the normals point inside (solidify tries to go to the outside `then) ![image](/attachments/43846979-4498-42bb-a59e-f7c3dfdeba1c) So it seems this does not really have to do with the fact of triangulation? In order to "fix" this, you can go into editmode, select everything and do `Mesh` > `Normals` > `Recalculate Outside`, does this give the expected results for you?

229 KiB

299 KiB

225 KiB

236 KiB

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labels 2024-04-19 14:45:56 +02:00

Pierre-Samuel-GREAU-HAMARD commented

2024-04-19 15:01:13 +02:00

Author

Hello,

Well, I was trying to push the solidification modifier to its limits by using it to turn messed up models into manifold ones, to make sure whatever the mesh, I could make it usable in the rest of my project, but I dropped that project almost a year ago, so I don't care anymore. If you think the modifier behaves as intended in this case, then it's fine.

Hello, Well, I was trying to push the solidification modifier to its limits by using it to turn messed up models into manifold ones, to make sure whatever the mesh, I could make it usable in the rest of my project, but I dropped that project almost a year ago, so I don't care anymore. If you think the modifier behaves as intended in this case, then it's fine.

Philipp Oeser commented

2024-04-19 17:00:40 +02:00

Member

Hello,

Well, I was trying to push the solidification modifier to its limits by using it to turn messed up models into manifold ones, to make sure whatever the mesh, I could make it usable in the rest of my project, but I dropped that project almost a year ago, so I don't care anymore. If you think the modifier behaves as intended in this case, then it's fine.

To me it looks it behaves correct, yes. It goes in one way with normals pointing outside and goes the other way with the normals pointing inside. The report mentioning that this has to do with triangulation: I see no evidence of that, none of the files here actually show a difference when the model is triangulated vs. when they are not triangulated afaict

> Hello, > > Well, I was trying to push the solidification modifier to its limits by using it to turn messed up models into manifold ones, to make sure whatever the mesh, I could make it usable in the rest of my project, but I dropped that project almost a year ago, so I don't care anymore. If you think the modifier behaves as intended in this case, then it's fine. To me it looks it behaves correct, yes. It goes in one way with normals pointing outside and goes the other way with the normals pointing inside. The report mentioning that this has to do with triangulation: I see no evidence of that, none of the files here actually show a difference when the model is triangulated vs. when they are not triangulated afaict

Philipp Oeser commented

2024-05-02 13:18:42 +02:00

Member

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed.

Thanks again for the report. If the problem persists please open a new report with the required information.

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed. Thanks again for the report. If the problem persists please open a new report with the required information.

Philipp Oeser closed this issue

2024-05-02 13:18:46 +02:00

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