Faces missing, weird faces added
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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

Weird faces bug (created in 2.81a).blend542 KBDownload

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

rB Blender
	rB592e306236de Fix T74024 Faces missing, weird faces added
	rB6d8b6aec1874 Fix T74024 Faces missing, weird faces added
	rB56d6666689f7 GPU: Limit Mesa workaround to older version

Related Objects

Mentioned In: rB76dcf70daced: Fix transparent faces on certain AMD cards
D9305: Fix transparent faces on certain AMD cards
T77348: Blender LTS: Maintenance Task 2.83
T78390: Assign Materials on Faces of an object
T74791: Crash trying to open Spring Splash scene
T74790: Artifacts in solid view
Mentioned Here: rB20605c4b515e: Modifiers: UVWarp modifier add invert vgroup option
rB56d6666689f7: GPU: Limit Mesa workaround to older version
T74019: High Quality Normals causing pitch black faces

Event Timeline

Georg K (georg) created this task.Feb 20 2020, 12:38 AM

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

Georg K (georg) updated the task description. (Show Details)Feb 20 2020, 12:51 AM

Cant redo:

OS: Linux 5.5.3-arch1-1
REV: 1e3ffd1f872b1a52a5c392b135c29ae71744137d
GPU: GeForce GTX 1080

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.

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

Georg K (georg) updated the task description. (Show Details)Feb 20 2020, 7:46 PM

Georg K (georg) updated the task description. (Show Details)Feb 20 2020, 9:26 PM

Campbell Barton (campbellbarton) added a commit: rB56d6666689f7: GPU: Limit Mesa workaround to older version.Feb 21 2020, 3:18 AM

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

Georg K (georg) updated the task description. (Show Details)Feb 21 2020, 9:11 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

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?

Georg K (georg) mentioned this in T74790: Artifacts in solid view.Mar 15 2020, 9:12 PM

Georg K (georg) mentioned this in T74791: Crash trying to open Spring Splash scene.Mar 15 2020, 9:19 PM

Georg K (georg) updated the task description. (Show Details)Mar 17 2020, 4:46 PM

Germano Cavalcante (mano-wii) changed the task status from Needs Information from User to Needs Information from Developers.Mar 30 2020, 4:19 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.

Weird faces bug - material slots (2.90beta).blend753 KBDownload

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

Georg K (georg) updated the task description. (Show Details)May 2 2020, 7:43 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?

Clément Foucault (fclem) removed a project: GPU / Viewport.Jun 19 2020, 10:23 PM

I honestly think this is a Mesa bug. The crash in 2.90 might be a separate issue. Please try with the latest build to see if the crash is fixed.

Maybe we can whitelist your GPU to always have the workaround.

Can you check if this patch fixes the issue:

diff --git a/source/blender/gpu/intern/gpu_extensions.c b/source/blender/gpu/intern/gpu_extensions.c
index ab55fcfb1e0..03d4cde985e 100644
--- a/source/blender/gpu/intern/gpu_extensions.c
+++ b/source/blender/gpu/intern/gpu_extensions.c
@@ -273,8 +273,8 @@ void gpu_extensions_init(void)
   const char *renderer = (const char *)glGetString(GL_RENDERER);
   const char *version = (const char *)glGetString(GL_VERSION);
 
-  if (GPU_type_matches(GPU_DEVICE_ATI, GPU_OS_WIN, GPU_DRIVER_OFFICIAL)) {
-    if (strstr(version, "4.5.13399") || strstr(version, "4.5.13417") ||
+  if (true || GPU_type_matches(GPU_DEVICE_ATI, GPU_OS_WIN, GPU_DRIVER_OFFICIAL)) {
+    if (true || strstr(version, "4.5.13399") || strstr(version, "4.5.13417") ||
         strstr(version, "4.5.13422")) {
       /* The renderers include:
        *   Mobility Radeon HD 5000;