Maniphest T98174

Assigning multiple materials to object breaks subdivision in Blender 3.1.2
Closed, Duplicate
Actions

Assigned To
None
Authored By
Shaoqing Li (Luna)
May 16 2022, 11:03 PM
Tags
  • BF Blender
Subscribers
Pratik Borhade (PratikPB2123)
Shaoqing Li (Luna)

Description

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 2.83.20, branch: master, commit date: 2022-04-19 16:00, hash: rBa56e2faeb7a9
Worked: (newest version of Blender that worked as expected)

Short description of error
Applying 2 Materials to an object when using mirror and subdivision causes the geometry of an object to break.

Exact steps for others to reproduce the error
Based on Default startup.

Create Sphere Primitive.
Delete Half the faces
Select some Faces and Apply a Material (Default)
Select some different faces (with some overlap) and apply second material (Default with edited colours)
Apply Mirror Modifier so it looks like a sphere again.
Apply Subdivision Surface Modifier.
Observe Geometry Breaks

Loading file in an older version of blender (2.8) the issue cannot be recreated.

Related Objects

Event Timeline

Shaoqing Li (Luna) created this task.May 16 2022, 11:03 PM
Shaoqing Li (Luna) added a comment.May 16 2022, 11:05 PM

My example Blender file:
https://drive.google.com/file/d/1ps2qs6xywoPDKLxbbTfDonJYn4jqbgcl/view?usp=sharing

Pratik Borhade (PratikPB2123) changed the task status from Needs Triage to Needs Information from User.EditedMay 17 2022, 6:18 AM
Pratik Borhade (PratikPB2123) added a subscriber: Pratik Borhade (PratikPB2123).

Hi, thanks for the report. Can you share screenshot to show how mesh appears in viewport?
I'm not seeing anything broken in 2.83.17 and latest 3.3 alpha.
Are you sure 2.83LTS is broken version? I'm seeing 3.1.2 in your file name and report header. probably same issue as in T96845: Regression: GPU Subdivision with mirror/Array modifier shows artifacts
Can you also check again in latest blender version?: https://builder.blender.org/download/daily

Shaoqing Li (Luna) added a comment.May 18 2022, 4:39 PM

Hi Pratik, please check this video - I recorded my screen while I open this file "https://drive.google.com/file/d/1ps2qs6xywoPDKLxbbTfDonJYn4jqbgcl/view?usp=sharing" in 3 different versions of Blender (include the newest 3.3 alpha), please feel free to check:
https://youtu.be/xHygzfoFnfY

Shaoqing Li (Luna) added a comment.EditedMay 18 2022, 4:40 PM

This file has no problem in both 2.83.17 and latest 3.3 alpha, the bug only existed in the blender 3.1.2 version as you can see in this screen recording: https://youtu.be/xHygzfoFnfY

Pratik Borhade (PratikPB2123) added a comment.May 18 2022, 5:40 PM

Hi, thanks for the information. Pretty sure this is same as- T96845: Regression: GPU Subdivision with mirror/Array modifier shows artifacts

the bug only existed in the blender 3.1.2 version

3.1 version is not maintained anymore. You can still fix this in 3.1 (and 3.1.2) by disabling GPU Subdivision: Edit → Preferences → Viewport → Subdivision → GPU Subdivision
Since latest versions are working correctly I'm closing this report.
Don't hesitate to comment if I've misunderstood anything

Pratik Borhade (PratikPB2123) closed this task as a duplicate of T96845: Regression: GPU Subdivision with mirror/Array modifier shows artifacts.May 18 2022, 5:41 PM