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Faces missing, weird faces added
Needs Developer to Reproduce, NormalPublicBUG

Description

System Information
Operating system: Linux-5.4.18-1-MANJARO-x86_64-with-glibc2.2.5 64 Bits
Graphics card: AMD VERDE (DRM 2.50.0, 5.4.18-1-MANJARO, LLVM 9.0.1) X.Org 4.5 (Core Profile) Mesa 19.3.4

Blender Version
Broken: 2.83 (sub 4), branch: master, commit date: 2020-02-18 17:20, hash: rB56d6666689f7 (bug introduced by https://developer.blender.org/rB56d6666689f7027126e8c115d01564810d1ae1bb)
(also broken: version: 2.83 (sub 4), branch: master, commit date: 2020-02-19 23:13, hash: rB0c01ad93004d)
(also broken: version: 2.83 (sub 4), branch: master, commit date: 2020-02-20 17:34, hash: rBa9b184bbc464)
(also broken: buildbot blender-2.83-ee7f307c9a11-linux64)
Worked: 2.83 (sub 4), branch: master, commit date: 2020-02-18 17:14, hash: rB20605c4b515e (last working rev)

Short description of error
Some faces are black, some are missing, new weird faces are added when entering edit mode from certain camera angles or they are already there when opening the file (like with the Spring scene). Switching between Object mode and Edit mode makes them disappear sometimes, but not for long.
2.81a:


2.83alpha:

It could be related to https://developer.blender.org/T74019 but it was not fixed by the fix.

New faces also visible in Spring splash scene (https://cloud.blender.org/p/gallery/5d2607ee6b3001d49bab798a) :



Those are not 2D artifacts but 3D geometry

Exact steps for others to reproduce the error
This does not happen with every mesh. It seems to be connected to ngon placement, but I cant exactly place my finger on it. Suzanne for example works fine.
Open


in 2.81a and in 2.83 dev. In 2.83 alpha, enter edit mode, move the camera, toggle in and out of edit mode - sometimes the mesh is changed by that.

Revisions and Commits

Event Timeline

Georg K (georg) updated the task description. (Show Details)

Cant redo:

  • OS: Linux 5.5.3-arch1-1
  • REV: 1e3ffd1f872b1a52a5c392b135c29ae71744137d
  • GPU: GeForce GTX 1080
Georg K (georg) added a comment.EditedFeb 20 2020, 12:25 PM

Also can't redo on skylake with integrated intel graphics, so I think this is related to AMD graphics.

Just to be sure, I clean built everything (same git revision), but the problem persists:
install_deps.sh --with-all --with-oidn --skip-osl --skip-embree --build-usd
(embree is giving errors so I had to skip it, usd is not found even with build-usd but building is successful anyway)

make -j8 BUILD_CMAKE_ARGS="-U *SNDFILE* -U *PYTHON* -U *BOOST* -U *Boost* -U *OPENCOLORIO* -U *OPENEXR* -U *OPENIMAGEIO* -U *LLVM* -U *CYCLES* -U *OPENSUBDIV* -U *OPENVDB* -U *COLLADA* -U *FFMPEG* -U *ALEMBIC* -U *USD* -D WITH_CODEC_SNDFILE=ON -D PYTHON_VERSION=3.8 -D WITH_OPENCOLORIO=ON -D WITH_CYCLES_OSL=OFF -D WITH_LLVM=OFF -D WITH_OPENSUBDIV=ON -D WITH_OPENVDB=ON -D WITH_OPENVDB_BLOSC=ON -D WITH_OPENCOLLADA=ON -D WITH_OPENIMAGEDENOISE=ON -D OPENIMAGEDENOISE_ROOT_DIR=/home/georg/Programme/blender-git/deps/oidn -D WITH_JACK=ON -D WITH_JACK_DYNLOAD=ON -D WITH_ALEMBIC=ON -D ALEMBIC_ROOT_DIR=/home/georg/Programme/blender-git/deps/alembic -D WITH_USD=ON -D WITH_CODEC_FFMPEG=ON -D FFMPEG_LIBRARIES='avformat;avcodec;avutil;avdevice;swscale;swresample;lzma;rt;theora;theoradec;theoraenc;vorbis;vorbisenc;vorbisfile;ogg;xvidcore;vpx;opus;mp3lame;x264;openjp2'"

Always have to modify PYTHON_VERSION to 3.8 manually, but I guess that is not the problem here.

Georg K (georg) added a comment.EditedFeb 20 2020, 4:11 PM

Used git reset --hard 20605c4b515e to go back to "Modifiers: UVWarp modifier add invert vgroup option" (Tue, Feb 18) 20605c4b515e prior to the two GPU commits and that build works fine.
So, working in version: 2.83 (sub 4), branch: master, commit date: 2020-02-18 17:14, hash: rB20605c4b515e

And the bug was introduced by commit 56d6666689f7 (https://developer.blender.org/rB56d6666689f7027126e8c115d01564810d1ae1bb):
2.83 (sub 4), branch: master, commit date: 2020-02-18 17:20, hash: rB56d6666689f7

Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Confirmed.EditedFeb 21 2020, 7:48 PM
Germano Cavalcante (mano-wii) changed the subtype of this task from "Report" to "Bug".

I cannot reproduce the problem, but I am confirming, since the commit that introduced the problem has been identified.

Jeroen Bakker (jbakker) changed the task status from Confirmed to Needs Information from User.Mar 13 2020, 5:09 PM

Does it help to start blender with --debug-gpu-force-workarounds If that is the case we should add this configuration to a enable the unused_fb_slot_workaround

Georg K (georg) added a comment.EditedMar 15 2020, 8:12 PM

Unfortunately, it does not help.
The situation has worsened in the meantime: in my current build version: 2.83 (sub 9), branch: master, commit date: 2020-03-15 18:22, hash: rB22925d0dd31e there are additional artifacts and trying to open the Spring splash scene (https://cloud.blender.org/p/gallery/5d2607ee6b3001d49bab798a) crashes blender. Both new problems are also exclusive to my HD7770 system and persist even if I revert commit 56d6666689f7, so I will make new reports.
Do you think you may have to drop support for GCN 1st gen systems like my Southern Islands HD7770 in the near future?

Germano Cavalcante (mano-wii) changed the task status from Needs Information from User to Needs Developer to Reproduce.Mar 30 2020, 4:19 PM
Georg K (georg) added a comment.EditedMay 2 2020, 7:11 PM

I found something: The trigger for this issue is material slot assignment!
Take our default cube, add two material slots (one is not enough), enter edit mode, assign one face to material slot 1 and a second face to material slot 2 - the second face vanishes! The material slots do not need to contain materials.
The additional geometry is only added to the sphere, so the shape seems to have an effect, too.

The artifacts are also in eevee F12 renders.


In the Spring splash scene, removing 2 material slots on each eye removed all artifacts.

Georg K (georg) added a comment.EditedTue, Jun 2, 7:54 PM

The issue is still present in 2.90 alpha with latest mesa 20.0.7:

System Information
Operating system: Linux-5.4.43-1-MANJARO-x86_64-with-glibc2.29 64 Bits
Graphics card: AMD VERDE (DRM 2.50.0, 5.4.43-1-MANJARO, LLVM 10.0.0) X.Org 4.5 (Core Profile) Mesa 20.0.7

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-01 12:22, hash: rB45dbc38a8b15

In addition to my last post, I found another problem without material slots involved: a primitive circle with default settings is displayed as a radius line (looks normal in Edit mode, but crashes when moving the viewport camera).

Testing the three code changes from commit 56d6666689f7 separately (ignoring the variable declaration):
reverting 1,2,3: issue gone, but Blender crashes when trying to move the viewport camera in the Spring scene (object mode). In the circle scene, I can rotate the camera in object mode, but trying to rotate the camera in Edit mode crashes Blender.
reverting 1: issue still there, Blender crashes when trying to move the viewport camera in the Spring scene (object mode). In the circle scene, I can rotate the camera in object mode, but trying to rotate the camera in Edit mode crashes Blender.
reverting 2: "
reverting 3: "
reverting 1+3: issue gone, but Blender crashes when trying to move the viewport camera in the Spring scene (object mode). In the circle scene, I can rotate the camera in object mode, but trying to rotate the camera in Edit mode crashes Blender.
reverting 2+3: "

The crashes occurred in 2.90 only, not in 2.83LTS (version: 2.83.0, branch: master, commit date: 2020-06-03 14:38, hash: rB211b6c29f771) but the visual problems are in both versions.

Is there anything I can do to help you solve this?