Regression: Removing shape keys via python iteration messes up normals #115572

New Issue

Nika Kutsniashvili · 2023-11-29T15:01:25+01:00

2023-11-29 15:01:25 +01:00

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1650/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 537.42

Blender Version
Broken: version: 4.0.0, branch: blender-v4.0-release, commit date: 2023-11-13 17:26, hash: 878f71061b8e
Worked: 3.6.5

Caused by 383a145a19

Short description of error
This is the strangest bug but this is EXTREMELY important for my workflow, as for many others as Keymesh add-on cannot properly function without this issue getting a fix.

When you apply shape keys with bpy.ops.object.shape_key_remove(all=True, apply_mix=True) it gives wrong normals in 4.0. I don't even know what to call it. It looks completely flat, even though shape is the same it seems.

When I use transfer mesh data operator (with any random object active) and randomly check-uncheck some boxes, it returns correct normals, but I can't get that to work with python, and its impossible to do it by hand on amount of objects I'm working on.

3.6

4.0

Exact steps for others to reproduce the error
I am attaching a blend file with test example. There is a cube with shape key. In Text editor there is a script that copies object and mesh on each frame in some range, aligns them next to each other, and applies shape keys on each of them.

Open file with 3.6 and 4.0, and run script in both. In 3.6 normals will be correctly kept. In 4.0 it will be completely flat.

I hope fix can be found quickly, this feature is imperative for my studios work

**System Information** Operating system: Windows-10-10.0.19043-SP0 64 Bits Graphics card: NVIDIA GeForce GTX 1650/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 537.42 **Blender Version** Broken: version: 4.0.0, branch: blender-v4.0-release, commit date: 2023-11-13 17:26, hash: `878f71061b8e` Worked: 3.6.5 Caused by 383a145a19 **Short description of error** This is the strangest bug but this is EXTREMELY important for my workflow, as for many others as Keymesh add-on cannot properly function without this issue getting a fix. When you apply shape keys with `bpy.ops.object.shape_key_remove(all=True, apply_mix=True)` it gives wrong normals in 4.0. I don't even know what to call it. It looks completely flat, even though shape is the same it seems. When I use transfer mesh data operator (with any random object active) and randomly check-uncheck some boxes, it returns correct normals, but I can't get that to work with python, and its impossible to do it by hand on amount of objects I'm working on. 3.6 ![image](/attachments/280309cb-e946-4b4d-b6bc-7c4199f861af) 4.0 ![image](/attachments/2441bfa4-b4a7-4458-b92b-0033fa2bea08) **Exact steps for others to reproduce the error** I am attaching a blend file with test example. There is a cube with shape key. In Text editor there is a script that copies object and mesh on each frame in some range, aligns them next to each other, and applies shape keys on each of them. Open file with 3.6 and 4.0, and run script in both. In 3.6 normals will be correctly kept. In 4.0 it will be completely flat. I hope fix can be found quickly, this feature is imperative for my studios work

image.png

207 KiB

shape_keys_remove.blend

2.8 MiB

image.png

211 KiB

Nika Kutsniashvili added the