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Maniphest T64284

Mirroed Collection Intances have flipped normals/face orientation.
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Description

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.39

Blender Version
Broken: version: 2.80 (sub 60), branch: blender2.7, commit date: 2019-05-07 19:17, hash: 3dc9da3a74ee
Worked: version: 2.80 (sub 60), branch: blender2.7, commit date: 2019-05-03 21:09, hash: ee0d8426ab6d

Short description of error
Mirroed collections instances have flipped normals in 3D viewport.
Screenshot of viewport with face orientation turned on.
Blue cube is the original mesh in a collection. Red cube is the collection instance mirroed in the X axis.

Exact steps for others to reproduce the error

  1. Create collection with any mesh.
  2. Add a Collection Instance of that collection
  3. Use mirror operator with any axis.

Revisions and Commits

rB Blender
rBc0b8d071a754 Fix T64284 Mirrored Instances have flipped normals/face orientation

Related Objects

Event Timeline

Rafael Fernandes Pereira (ragatol) created this task.May 8 2019, 4:37 AM
Sebastian Parborg (zeddb) assigned this task to Clément Foucault (fclem).May 8 2019, 12:50 PM
Sebastian Parborg (zeddb) lowered the priority of this task from 90 to 50.
Sebastian Parborg (zeddb) added a subscriber: Sebastian Parborg (zeddb).

Bisected down to: rBddb71e8c20c2ceba61b4ebddc602adc5b8eed5c8

Jeroen Bakker (jbakker) claimed this task.EditedMay 9 2019, 3:26 PM
Jeroen Bakker (jbakker) added a subscriber: Clément Foucault (fclem).

According to @Clément Foucault (fclem) correct fix is to use apply the flag OB_NEG_SCALE on dupli if the parent has the flag. and remove it if both are true would be nice to have that done in the depsgraph tho

Sebastian Parborg (zeddb) added a subscriber: Sergey Sharybin (sergey).May 9 2019, 3:31 PM

@Jeroen Bakker (jbakker) so should we poke @Sergey Sharybin (sergey) about this?

Jeroen Bakker (jbakker) added a comment.May 9 2019, 4:12 PM

@Sebastian Parborg (zeddb) yes, I also want a good opinion about it. currently OB_NEG_SCALE (and its draw manager counterpart DRW_CALL_NEGSCALE) only influences the BACK face checking, what is too limmitted. I can see @Clément Foucault (fclem) analysis to be correct. But before we put any change in depsgraph I want to have some guidance on where and how.

Clément Foucault (fclem) added a comment.May 9 2019, 4:19 PM

My guess would be deg_objects_dupli_iterator_next

Jeroen Bakker (jbakker) added a comment.May 10 2019, 9:24 AM

We noticed that normals are off due to recent changes. Here I will elaborate what my findings are. More issues I have seen might be related to this.

Scene I used for testing

T64284.blend609 KBDownload

4 days ago rB21f8e75ddb6b: fix image_changed() doing unneccessary texture updates when texture wasnt using… everything seems correct


Current master rB6b082278d195: UI: expose tool settings in the 3D view side-bar shows normals inverted and mirrored

Somewhere in between I see flipped normals (but not mirrored)

The inverted normals are introduced by rBddb71e8c20c2: DRW: Remove is_negative_m4 per draw call
The mirrored normals are introduced by rB733811330c9b: Workbench: Use common_view_lib and remove NormalMatrix usage

It might be that the mirrored normals was a fix so we need to check this against EEVEE normals in this case.

Broken eevee normals are introduced by rBf2f62b184c67: DRW: Remove WorldNormalMatrix

Clément Foucault (fclem) changed the task status from Unknown Status to Resolved by committing rBc0b8d071a754: Fix T64284 Mirrored Instances have flipped normals/face orientation.May 10 2019, 2:48 PM
Clément Foucault (fclem) added a commit: rBc0b8d071a754: Fix T64284 Mirrored Instances have flipped normals/face orientation.
Sebastian Koenig (sebastian_k) mentioned this in T64249: Mirrored collection instances have wrong shading.May 10 2019, 3:58 PM
Emir Sinan Gürlek (filibis) changed the task status from Resolved to Unknown Status.Jun 20 2019, 9:49 PM
Emir Sinan Gürlek (filibis) added a subscriber: Emir Sinan Gürlek (filibis).

I think this issue hasn't been fixed properly or popped again. I'm getting artifacts when I select a mirror object to use as mirror.
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-19 18:29, hash: rBd30f72dfd8ac

chair_mirror_bug.blend1 MBDownload

Jeroen Bakker (jbakker) changed the task status from Unknown Status to Resolved.Jun 27 2019, 10:52 AM

Hello, @Emir Sinan Gürlek (filibis)

Sorry for this, but could you please open a new report, it is not related to this issue. Your issue is related to autosmooth. When you disable autosmoothing it renders fine.
I will change this issue to resolve as this is related to collections mirroring, what is working as expected.

Emir Sinan Gürlek (filibis) added a comment.Jun 27 2019, 3:22 PM

Sorry @Jeroen Bakker (jbakker) , I thought the issue is related. I created a new report for this: T66183