OBJ meshes get corrupted on reimport on Android editor

[Booklight12]

Godot version

4.1.stable

System information

Android13

Issue description

I'm trying to import the obj model file on Android but there seems to be some compatibility issues? You can do two tests on both the computer and the mobile side to make sure what I'm saying is true.

Steps to reproduce

Create an obj file and import it into the Godot engine on Android.

Minimal reproduction project

test.zip

[Booklight12]

Under no circumstances should a cube look like this

[Booklight12]

I need to declare that this is a "door" resource that I found from itch resources, but it appears in such a state in the engine.

[Zireael07]

Are you 100% sure the models look proper in Blender, that the materials aren't set as two-sided

[Booklight12]

This is the obj file from my last photo, you can try opening it on blender
door

[Booklight12]

For files exported by blender this is completely invisible in the editor

[Booklight12]

You can see the object only in the preview，It looks like this in blender

[Booklight12]

您是否 100% 确定模型在 Blender 中看起来正确，材质未设置为双面

sure

[Booklight12]

I tested it on another Android device

[Booklight12]

I don't understand why this is happening, it's affecting development.

[Booklight12]

Other applications can be displayed normally (including maya)

[Booklight12]

Watch this video

[fire]

I can confirm that that the cube's bottom triangle is missing on the cached project.

But working as a scene on steam stable.

[fire]

Maybe the 4.1.1 version fixed the problem.

[fire]

@clayjohn @m4gr3d @BastiaanOlij Any ideas how to test on Android? The broken obj import seems to be a specific bug.

[Booklight12]

4.1.1 did not fix the problem, in fact, when I repeatedly tried to import obj files, I found that their shapes would become strange

[akien-mga]

I confirm the bug with 4.1.1 on Android (Xiaomi Poco F1). Both the mobile and GL renderer seem to have the same issue.

I tried switching the MRP's obj to import as scene, which didn't solve it, but after switching back to import as mesh I managed to get a good import (3 default cubes). Then hitting reimport again made the cubes disappear.

[Booklight12]

sure

[bitsawer]

Possibly related if the mesh reimport process tries to read back mesh data at some point: #75599

[Booklight12]

This is the error reported when exporting. Is there anything else I can do?

[Booklight12]

Please, fixing this bug is important to me

[Calinou]

Please, fixing this bug is important to me

Issues are resolved by contributors on a best-effort basis. We can't provide an ETA on when this will be fixed.

[ZeroLikviz]

hi guys, I have an idea why this might be happening. I have 2 devices: realme c21 with android 11 and Xiaomi pad 5 with android 13. I've been programming on both of them using C++. I have created a graphical application using SDL2. As you know, SDL2 uses double buffering, and if everything was fine on Realme, then on Xiaomi pad 5 the second buffer was constantly changing, various incomprehensible pieces appeared there, and sometimes it was completely cleaned. I solved the problem by manually creating a buffer.

As I said, the problem was only on the Xiaomi pad 5. I decided to check if the problem is related to the device. I asked a friend for a Poco x 3 pro and after launching the program, I realized that the problem was related to either MIUI or android 13.

In the end, I decided to download Godot 4 on Realme c21 and the result only confirmed my theory: the problem is related to either MIUI or android 13. As far as I understand, something affects dynamic memory when no one uses it and in order to solve the problem, it is necessary to save data in dynamic memory, until then, while this data will not be needed. Also, the erase command sometimes breaks data in the container, I didn't look at the code, but if the erase command is used, then you should be more careful with it.

I hope this information helps a little.

Realme c21:

Xiaomi pad 5:

Screenrecorder-2023-10-30-18-48-26-217.mp4

here is some more information:
• I saved the resulting mesh into a variable and then started constantly assigning it to CSGMesh3d.mesh, as a result, the shape was incorrect, but it has not changed during test
• I tried to do the same thing, but instead of mesh I assigned mesh.duplicate(), as a result the form was constantly changing

Xiaomi pad 5:

Screenrecorder-2023-10-30-21-12-02-144.mp4

I saved the mesh when it took the correct shape and then I tried assigning the mesh to CSGMesh3D many times. As a result, the mesh that was in CSGMesh3D was constantly changing.

Screenrecorder-2023-10-30-21-37-44-227.mp4