Gltf-blender-io: 2.90.1 or 2.83.8 export gltf crashes on ubuntu 20.10 but working on ubuntu 20.04 same machine

[mandolinci]

Describe the bug
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2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
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Screenshots
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.blend file/ .gltf
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Version

• OS: [e.g. macOS, linux]
• Blender Version [e.g. 2.82, 2.83, or build date]

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[julienduroure]

Hello,
You didn't fill any information that are in the template.
We can't investigate without these data (for example test file).
Regarding the title, please indicate how you get blender : from apt-get or from downloading from https://www.blender.org/download/

[mandolinci]

I use default cube scene.
I tried both snap installation and without an installation, running from extracted folder
blender-2.90.1-linux64.tar.xz
blender-2.83.8-linux64.tar.xz
before ugrade new operation system ubuntu 20.10
I was using ubuntu 20.04 and it was working
now on ubuntu 20.10 other export methods works. just gltf crashes
I run from terminal to get error message but I dont know how to find the "core dumped" file

:~/$ blender
Read prefs: /home/u/.config/blender/2.90/config/userpref.blend
/run/user/1000/snap.blender/gvfs/ non-existent directory
found bundled python: /snap/blender/47/2.90/python
Aborted (core dumped)

:~/Downloads/blender-2.90.1-linux64$ ./blender
Read prefs: /home/u/.config/blender/2.90/config/userpref.blend
found bundled python: /home/u/Downloads/blender-2.90.1-linux64/2.90/python
Aborted (core dumped)

[julienduroure]

Seams your problem is linked to your operating system, not from this addon.
Anyone else tested the newly out ubuntu 20.10?

[scurest]

Suspect a problem with the draco .so. After you unpack Blender, find a file named something like

2.90/python/lib/python3.7/site-packages/libextern_draco.so

and delete it.

[mandolinci]

I deleted "libextern_draco.so" but nothing changed

[scurest]

It crashes really early, before this line finishes, because you're not even getting the message about if the draco .so was found.

Try replacing the __init__ function there with

py def __init__(self): print('got to init') self.is_draco_available = False

and see if it prints the message.

[mandolinci]

I update the file. this time save diyalog opened and when I press "export gltf2" button then It crashed. before update this file. It doesnt open the save dialog

the terminal message

Read prefs: /home/u/.config/blender/2.90/config/userpref.blend
found bundled python: /home/u/Downloads/blender-2.90.1-linux64/2.90/python
got to init
Aborted (core dumped)

[scurest]

Okay, try this and see what it prints

py def __init__(self): print('got to A') from io_scene_gltf2.io.exp import gltf2_io_draco_compression_extension print('got to B') self.is_draco_available = gltf2_io_draco_compression_extension.dll_exists() print('got to C')

[mandolinci]

found bundled python: /home/u/Downloads/blender-2.90.1-linux64/2.90/python
got to A
Aborted (core dumped)

[scurest]

Try

````py

def __init__(self):
    print('got to A')
    import bpy
    print('got to 1')
    import sys
    print('got to 2')
    from ctypes import c_void_p, c_uint32, c_uint64, c_bool, c_char_p, cdll
    print('got to 3')
    from pathlib import Path
    print('got to 4')
    import struct
    print('got to 5')
    from io_scene_gltf2.io.exp import gltf2_io_draco_compression_extension
    print('got to B')
    self.is_draco_available = gltf2_io_draco_compression_extension.dll_exists()
    print('got to C')

````

[mandolinci]

got to A
got to 1
got to 2
Aborted (core dumped)

[scurest]

I thought it would be that.

Can you open Blender, switch to a Python Console, put from ctypes import c_void_p, c_uint32, c_uint64, c_bool, c_char_p, cdll at the prompt, and see if it crashes?

[mandolinci]

yes it crasched again. and I tried first
from ctypes import c_void_p, c_uint32, c_uint64, c_bool, c_char_p, cdll
then the less combinations like
from ctypes import c_void_p
or
from ctypes import cdll
all of them crashed
then I run python on terminal and try to import again but didnt crashed

it crashed in the blender console

[scurest]

Okay, cool. Thanks for doing all that. The problem is importing ctypes then. You could also try running the Python located in the Blender dir at 2.90/python/bin/ in terminal and seeing if the crashes there too.

So yeah, this isn't really a problem with this addon. I guess you could file it upstream with Blender (or Ubuntu?).

In the meantime, here's a workaround that should make glTF export work. Modify io_scene_gltf2/io/exp/gltf2_io_draco_compression_extension.py like this.

````diff
diff --git a/addons/io_scene_gltf2/io/exp/gltf2_io_draco_compression_extension.py b/addons/io_scene_gltf2/io/exp/gltf2_io_draco_compression_extension.py
index 2bb79aa..7824964 100644
--- a/addons/io_scene_gltf2/io/exp/gltf2_io_draco_compression_extension.py
+++ b/addons/io_scene_gltf2/io/exp/gltf2_io_draco_compression_extension.py
@@ -14,7 +14,6 @@

import bpy
import sys
-from ctypes import c_void_p, c_uint32, c_uint64, c_bool, c_char_p, cdll
from pathlib import Path
import struct

@@ -59,6 +58,7 @@ def compress_scene_primitives(scenes, export_settings):
Invoked after data has been gathered, but before scenes get traversed.
Moves position, normal and texture coordinate attributes into a Draco compressed buffer.
"""

• from ctypes import c_void_p, c_uint32, c_uint64, c_bool, c_char_p, cdll

 # Load DLL and setup function signatures.
 # Nearly all functions take the compressor as the first argument.

````

This only imports ctypes if we need it, which is only when you turn on mesh compression (Geometry > Compression on the export screen). As long as you keep that off, ctypes won't be imported, so you won't crash.

[scurest]

(You might also test if import numpy works. We need that too.)

[mandolinci]

import numpy also crasched

I tried blender located python3.7m. it works for all imports ctype and numpy. but not working in the python console in blender

then I make the change you did in the file "gltf2_io_draco_compression_extension.py" - and + updates. but gltf export is dissappered in the export menu

[scurest]

Oh, well if you can't import numpy, then there's no workaround. We need that to do anything :/

I'd try filing a bug with either Blender or Ubuntu telling them you can't do import numpy or import ctypes from Blender. Sorry, that's all I can tell you.

[mandolinci]

thank you very much

[julienduroure]

Ok, as suggested by scurest, I propose you to fill a bug with either Blender or Ubuntu teams.
I am going to close this ticket. Don't hesitate to comment if you want to add something.
Thanks ! (and sorry to not be able to help on that specific subject)

@scurest Thougth you ping me me that, but I can't find it anymore.

[scurest]

This bug has made its way upstream to Blender: https://developer.blender.org/T84752. There is a workaround there in case it helps anyone.