Normals not properly updating when using a Deform modifier after a Data Transfer (Custom Normals) modifier #94838

New Issue

aVersionOfReality · 2022-01-12T05:59:11+01:00

aVersionOfReality commented

2022-01-12 05:59:11 +01:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX TITAN X/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12

Blender Version
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: f1cca30557

Short description of error
If you transfer vertex Normals with the Data Transfer modifier, and then deform the mesh with modifiers placed afterwards, it does not properly update the Normals in many instances. However, it starts working if you put a modifier that alters the mesh after the Data Transfer and before the deforming modifier.

For example, if you do an Edge Split modifier and uncheck Edge Angle and have no edges marked Sharp Edges, then the problem does not occur. If you uncheck Sharp Edges, then it comes back. Or if you use a Decimate Modifier set on Planar with a tiny Angle Limit like 0.0001, the problem goes away even though the mesh hasn't actually changed.

Demonstration:
Plane A is having Normals transferred from B, which is having them transferred from C. A toon shader material is on to make it easy to see shading differences. Plane C is being bent into a Cylinder with a Simple Deform modifier.

On row 1, there is no deformation of B and so no problem.
On row 2, B is being Twisted with a Simple Deform modifier placed after the Data Transfer. The shading has gotten messed up and is not accurate to the twisted shape. This bad shading is properly transferred to A.
On row 3, B is the same but has a Edge Split modifier placed after the Data Transfer and before the Twist. It behaves properly, and A gets the Twisted Normals.

DataTransfer_bug-1.blend

Exact steps for others to reproduce the error

Add any object with enough vertices to notice a difference in Normals.
Duplicate it.
Deform the duplicate in some way, such as with a Simple Deform modifier.
Add a Data Transfer modifier to the original object, targeting the duplicate, and set to Custom Normals (Mix mode and mapping does not seem to matter, but Replace and Topology are easiest.)
Deform the original with a Deform modifier placed after the Data Transfer modifier.
It should be clear to see that the Normals have not properly changed even with default viewport materials.

Add an Edge Split modifier before the Deform modifier and uncheck Edge Angle. It should now look correct.

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce GTX TITAN X/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12 **Blender Version** Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: `f1cca30557` **Short description of error** If you transfer vertex Normals with the Data Transfer modifier, and then deform the mesh with modifiers placed afterwards, it does not properly update the Normals in many instances. However, it starts working if you put a modifier that alters the mesh after the Data Transfer and before the deforming modifier. For example, if you do an Edge Split modifier and uncheck Edge Angle and have no edges marked Sharp Edges, then the problem does not occur. If you uncheck Sharp Edges, then it comes back. Or if you use a Decimate Modifier set on Planar with a tiny Angle Limit like 0.0001, the problem goes away even though the mesh hasn't actually changed. **Demonstration:** Plane A is having Normals transferred from B, which is having them transferred from C. A toon shader material is on to make it easy to see shading differences. Plane C is being bent into a Cylinder with a Simple Deform modifier. - On row 1, there is no deformation of B and so no problem. - On row 2, B is being Twisted with a Simple Deform modifier placed after the Data Transfer. The shading has gotten messed up and is not accurate to the twisted shape. This bad shading is properly transferred to A. - On row 3, B is the same but has a Edge Split modifier placed after the Data Transfer and before the Twist. It behaves properly, and A gets the Twisted Normals. ![image.png](https://archive.blender.org/developer/F12801800/image.png) [DataTransfer_bug-1.blend](https://archive.blender.org/developer/F12801810/DataTransfer_bug-1.blend) **Exact steps for others to reproduce the error** - Add any object with enough vertices to notice a difference in Normals. - Duplicate it. - Deform the duplicate in some way, such as with a Simple Deform modifier. - Add a Data Transfer modifier to the original object, targeting the duplicate, and set to Custom Normals (Mix mode and mapping does not seem to matter, but Replace and Topology are easiest.) - Deform the original with a Deform modifier placed after the Data Transfer modifier. - It should be clear to see that the Normals have not properly changed even with default viewport materials. # Add an Edge Split modifier before the Deform modifier and uncheck Edge Angle. It should now look correct.

aVersionOfReality commented

2022-01-12 05:59:11 +01:00

Added subscriber: @ColinBarton

Germano Cavalcante commented

2022-01-14 20:10:45 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2022-01-14 20:10:45 +01:00

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

Germano Cavalcante closed this issue

2022-01-14 20:10:45 +01:00

Germano Cavalcante self-assigned this 2022-01-14 20:10:45 +01:00

Germano Cavalcante commented

2022-01-14 20:10:45 +01:00

I reproduced this bug in the build from yesterday, but not with the latest development build
This issue seems to be resolved with cfa53e0fbe.
So I believe we can close it as resolved.

Please try again when the next build is available.

I reproduced this bug in the build from yesterday, but not with the latest development build This issue seems to be resolved with cfa53e0fbe. So I believe we can close it as resolved. Please try again when the next build is available.

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Normals not properly updating when using a Deform modifier after a Data Transfer (Custom Normals) modifier #94838

Add an Edge Split modifier before the Deform modifier and uncheck Edge Angle. It should now look correct.