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Mesh bisect can make face disappear
Closed, ResolvedPublicBUG


System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: Quadro RTX 3000/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 452.69

Blender Version
Broken: version: 2.93.0 Beta, branch: master, commit date: 2021-04-26 22:01, hash: rB14b26fc97659
Worked: None ? Same problem in various versions (2.83, 2.92)

Short description of error
When applying a bisect, it sometimes fail to cut a face crossed by the plane - the face disappears from the mesh.
Changing the Axis Threshold seem to change this behaviour.

Exact steps for others to reproduce the error

  • Open the attached blend file.
  • Select Mesh / Bisect operation
  • Draw some vectical line to start the operation
  • Then change the input values with :
    • Plane Point : 0.15m, 0, 0
    • Plane Normal : -1, 0, 0
    • Clear outer : enabled
  • The face disappears
  • Change the Axis Threshold value to 0.0 to have the face re-appear

Edit: added more complex test with mirror + bisect

Event Timeline

Himanshi Kalra (calra) changed the task status from Needs Triage to Confirmed.Apr 27 2021, 9:24 PM
Himanshi Kalra (calra) changed the subtype of this task from "Report" to "Bug".

I can confirm this on Windows 10.
Thanks for the report.

It looks like a floating point error with threshold.
Default threshold value is 0.0001, manually retyping it to 0.0 fixes the issue as told by OP

Can reproduce with attached file but not able to reproduce even with a simple cube mesh