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Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors after topology changes [new or deleted] (if CustomSplitNormals are present)
Closed, ResolvedPublicBUG

Description

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 980/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.87

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-22 12:02, hash: rB8d1123ba220b
Worked: Blender 2.83 LTS
Caused by rB93c8955a722b: Mesh Edit: preserve Custom Normal vectors in topology operators.

Short description of error
Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors on new vertices, please see the video or the attached .blend file.

Exact steps for others to reproduce the error

  1. Open the attached file
  2. Press J to cut polygons between selected vertices
  3. Select new vertex
  4. Slide it with G G hotkeys
  5. If you Undo the Vertex Slide, you can slide it again without this problem, but as soon you create a new geometry -- it happens again
  6. Same happens with Loop Cut and Slide tool (Ctrl + R)

Thank you for checking out this bug!

Event Timeline

Yan Kansky (Yan_Kansky) renamed this task from Vertex Slide tool breaks the UVs and Vertex Colors on new vertices to Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors on new vertices.Sep 22 2020, 5:17 PM
Yan Kansky (Yan_Kansky) updated the task description. (Show Details)
Martijn Versteegh (Baardaap) changed the task status from Needs Triage to Confirmed.Sep 22 2020, 7:23 PM

As I have everything set up for git bisecting between 2.83 and 2.90 I'll do a bisect and find out which commit introduced this.

I'm done bisecting.

The first offending commit is 93c8955a7

Mesh Edit: preserve Custom Normal vectors in topology operators.

I have no clue how this code works, so someone else should look into it.

Philipp Oeser (lichtwerk) renamed this task from Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors on new vertices to Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors on new vertices (if CustomSplitNormals are present).Sep 23 2020, 12:44 PM
Philipp Oeser (lichtwerk) changed the subtype of this task from "Report" to "Bug".Sep 23 2020, 12:49 PM

Can confirm, it happens only when CustomSplitNormals are present!

Philipp Oeser (lichtwerk) renamed this task from Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors on new vertices (if CustomSplitNormals are present) to Vertex Slide and Loop Cut and Slide tools breaks the UVs and Vertex Colors after topology changes [new or deleted] (if CustomSplitNormals are present).Oct 2 2020, 9:30 AM
Philipp Oeser (lichtwerk) triaged this task as High priority.