Regression: Exported sculpt details are missing till you press clear custom split normals (e.g. after FBX export/import roundtrip) #96894

New Issue

Angelos Axiotis · 2022-03-30T15:52:17+02:00

Angelos Axiotis commented

2022-03-30 15:52:17 +02:00

System Information
Operating system: Windows-11 64 Bits
Graphics card: NVIDIA GeForce RTX 3080 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 497.17

Blender Version
Broken: version: 3.1.0, branch: master, commit date: 2022-03-08 18:16, hash: c77597cd0e
Worked: 3.0.1

Caused by cfa53e0fbe

Short description of error
Sculpting - When you export a sculpted mesh and you reimport it details are missing till you press clear custom split normals.
For example if I try to bake the high poly to substance painter I don't have the details of my sculpted mesh.

Exact steps for others to reproduce the error

Open default sculpting file -> sculpt a mesh
Export it in FBX format with default settings
Open default scene -> delete everything -> import the FBX file
(this is what you see when you re-import it)

the sculpted are shows on the side view

if you hit clear custom split normals the details will show up!

**System Information** Operating system: Windows-11 64 Bits Graphics card: NVIDIA GeForce RTX 3080 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 497.17 **Blender Version** Broken: version: 3.1.0, branch: master, commit date: 2022-03-08 18:16, hash: `c77597cd0e` Worked: 3.0.1 Caused by cfa53e0fbe **Short description of error** Sculpting - When you export a sculpted mesh and you reimport it details are missing till you press clear custom split normals. For example if I try to bake the high poly to substance painter I don't have the details of my sculpted mesh. **Exact steps for others to reproduce the error** - Open default sculpting file -> sculpt a mesh ![Screenshot 2022-03-30 153845.png](https://archive.blender.org/developer/F12957258/Screenshot_2022-03-30_153845.png) - Export it in FBX format with default settings - Open default scene -> delete everything -> import the FBX file (this is what you see when you re-import it) ![Screenshot 2022-03-30 153949.png](https://archive.blender.org/developer/F12957261/Screenshot_2022-03-30_153949.png) the sculpted are shows on the side view ![Screenshot 2022-03-30 154022.png](https://archive.blender.org/developer/F12957263/Screenshot_2022-03-30_154022.png) if you hit clear custom split normals the details will show up! ![Screenshot 2022-03-30 154049.png](https://archive.blender.org/developer/F12957267/Screenshot_2022-03-30_154049.png) ![Screenshot 2022-03-30 154059.png](https://archive.blender.org/developer/F12957273/Screenshot_2022-03-30_154059.png)

Angelos Axiotis commented

2022-03-30 15:52:17 +02:00

Added subscriber: @angelo9888

Philipp Oeser commented

2022-03-30 17:01:01 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-03-30 17:01:01 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Philipp Oeser commented

2022-03-30 17:01:01 +02:00

First things first:

When you export a sculpted mesh and you reimport it

Which exporter/importer is used here? Or do you mean save/append?

First things first: > When you export a sculpted mesh and you reimport it Which exporter/importer is used here? Or do you mean save/append?

Angelos Axiotis commented

2022-03-30 18:13:00 +02:00

The fbx importer/exporter.

Pratik Borhade commented

2022-03-31 07:14:50 +02:00

Added subscriber: @PratikPB2123

TheRedWaxPolice commented

2022-04-01 03:12:42 +02:00

Added subscriber: @TheRedWaxPolice

TheRedWaxPolice commented

2022-04-01 03:12:42 +02:00

In #96894#1332411, @angelo9888 wrote:
The fbx importer/exporter.

Interesting...
If you turn off "Auto Smooth" it fixes it, right?
Alternatively you can uncheck "Custom Normals" when importing the fbx to not include it...
So not sure if there's a bug here.. 🤔

> In #96894#1332411, @angelo9888 wrote: > The fbx importer/exporter. Interesting... If you turn off "Auto Smooth" it fixes it, right? Alternatively you can uncheck "Custom Normals" when importing the fbx to not include it... So not sure if there's a bug here.. 🤔

Angelos Axiotis commented

2022-04-01 16:54:32 +02:00

"If you turn off "Auto Smooth" it fixes it, right?"

no it doesn't .
My problem is not when importing it. My problem is when I export it and want to bake it as high poly in substance painter. There are no details!

"If you turn off "Auto Smooth" it fixes it, right?" - no it doesn't . My problem is not when importing it. My problem is when I export it and want to bake it as high poly in substance painter. There are no details!

Angelos Axiotis commented

2022-04-01 16:57:34 +02:00

"If you turn off "Auto Smooth" it fixes it, right?"
Correction it does fix the problem but when you import the model, not when you export it.
In a few words I want to use the high poly model outside of blender and I cannot because there are no details on the model!

"If you turn off "Auto Smooth" it fixes it, right?" Correction it does fix the problem but when you import the model, not when you export it. In a few words I want to use the high poly model outside of blender and I cannot because there are no details on the model!

Pratik Borhade commented

2022-04-14 07:54:04 +02:00

Changed status from 'Needs User Info' to: 'Confirmed'

Pratik Borhade commented

2022-04-14 07:54:04 +02:00

Added subscriber: @HooglyBoogly

Pratik Borhade commented

2022-04-14 07:54:04 +02:00

I'm able to reproduce this. Behavior changed between 97c2c39916 - e69020ad0f.
I suspect cfa53e0fbe
@HooglyBoogly hi, I don't think this is expected. Can you take a look?

I'm able to reproduce this. Behavior changed between 97c2c3991620 - e69020ad0f52. I suspect cfa53e0fbe @HooglyBoogly hi, I don't think this is expected. Can you take a look?

Pratik Borhade changed title from ~~Sculpting - exported sculpt details are missing till you press clear custom split normals~~ to FBX: Exported sculpt details are missing till you press clear custom split normals

2022-04-14 07:59:17 +02:00

Philipp Oeser commented

2022-04-14 13:03:09 +02:00

Will raise priority here since it is a regression.

Philipp Oeser changed title from ~~FBX: Exported sculpt details are missing till you press clear custom split normals~~ to Regression: Exported sculpt details are missing till you press clear custom split normals (e.g. after FBX export/import roundtrip)

2022-04-14 13:04:13 +02:00

Hans Goudey commented

2022-04-15 19:51:41 +02:00

I think I've found the problem-- while sculpt mode does update the mesh's original normals array while sculpting, it doesn't seem to set the dirty tags correctly.

I think the ideal loop (when there are no modifiers and we sculpt without Dyntopo or Multires) is this:

Sculpt brush adjusts positions
Sculpt code tags normals dirty
Sculpt code recalculates normals with PBVH structure, and clear dirty flag (a future optimization is skipping this step if modifiers will change the mesh anyway)

It seems that changes to vertex positions aren't always flushed to the original object when sculpting, which complicates this design a bit. (Conceptually, is sculpt mode really adjusting the original mesh, or some quasi-copy of it?)
I think I'll have to get some feedback from the people who have designed this area before applying that solution.

I think I've found the problem-- while sculpt mode does update the mesh's original normals array while sculpting, it doesn't seem to set the dirty tags correctly. I think the ideal loop (when there are no modifiers and we sculpt without Dyntopo or Multires) is this: - Sculpt brush adjusts positions - Sculpt code tags normals dirty - Sculpt code recalculates normals with PBVH structure, and clear dirty flag (a future optimization is skipping this step if modifiers will change the mesh anyway) It seems that changes to vertex positions aren't always flushed to the original object when sculpting, which complicates this design a bit. (Conceptually, is sculpt mode really adjusting the original mesh, or some quasi-copy of it?) I think I'll have to get some feedback from the people who have designed this area before applying that solution.

Hans Goudey commented

2022-11-17 01:00:37 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Hans Goudey closed this issue

2022-11-17 01:00:37 +01:00

Hans Goudey self-assigned this 2022-11-17 01:00:37 +01:00

Hans Goudey commented

2022-11-17 01:00:37 +01:00

This was resolved as part of e8f4010611. Sculpt mode needed proper handling of "positions changed" tagging for bounding boxes, which also applied here. I think there are still some logical issues with sharing the positions and normals arrays with the original mesh in some cases, but D15982 will give us new opportunities to simplify this area, so I think we can look at it again after that lands.

This was resolved as part of e8f4010611e7. Sculpt mode needed proper handling of "positions changed" tagging for bounding boxes, which also applied here. I think there are still some logical issues with sharing the positions and normals arrays with the original mesh in some cases, but [D15982](https://archive.blender.org/developer/D15982) will give us new opportunities to simplify this area, so I think we can look at it again after that lands.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Regression: Exported sculpt details are missing till you press clear custom split normals (e.g. after FBX export/import roundtrip) #96894