Godot 4.1 Screen flickering in random colors.

[NancokPS2]

Godot version

v4.1.stable.official [9704596]

System information

Windows 10 x64 - Godot v4.1 - OpenGL (Compatibility) - dedicated. GPU: FirePro v4900. CPU: AMD Phenom II X6

Issue description

The viewport is constantly flickering between colors no matter the scene or project. Compatibility mode both in the editor and when running.
The issue does not seem to come into effect during runtime.

Steps to reproduce

• Create project, see the issue.

Minimal reproduction project

N/A

Update:
It seems to be an issue with cached shaders from a previous version(?)
No idea honestly, it seems to be working fine so far.

[Calinou]

• This is likely due to the same cause as Godot 4.3 dev5 Weird floating plane mesh and black flickering screen. #78936.

If you can compile the engine from source, you could look into bisecting the regression to greatly speed up troubleshooting. In fact, this is probably the only way this issue could be resolved, as nobody else has been able to reproduce it so far.

[NancokPS2]

Thanks, i will try that.

I'll be keeping note of the possible culprits in this comment:
Broken between versions:
v4.1.rc1.official [1f9e540]
and
v4.1.rc2.official [4642448]

Working commits so far:
1f9e540 <-- Apparently this is bad too
1f9e540
9a09ee5
f228fb7
16dd4e5
Bad commits:
ab430b0
818cee6

Other possible factors:
.godot/shader_cache/

[NancokPS2]

Possible fix found:
Project Setting "rendering/textures/default_filters/use_nearest_mipmap_filter" must be true to avoid the bug.
Probably wrong, ignore.

If a .godot/shader_cache/ folder from a previous versions is used, this may not be necessary (for some reason).

Update:
Looks like it is an issue with shaders not caching properly, deleting shader_cache and re-opening the project seems to fix it. (?)

Re-Update:
The bug tends to re appear when new meshes are created in the editor, but to a less extreme extent. Reloading the project fixes it quickly

[Foxysen]

The effect on my laptop is more like disappearing meshes/graphic, but the causes seem to be similar. Doesn't happen in 4.0.3, sure does in 4.1.0. Appears to pop when it tries to save shader cache. Like it once had graphic glitch out at the same moment as it informed me that it failed to save shader cache but file was locked. But it sorta sometimes happens and sometimes doesn't on successful cache saves.

OpenGL mode. Only 3D scenes.

[Foxysen]

Oh, right, I just noticed the setting to disable shader caching in 4.1.0 (Rendering->Shader Compiler->Enabled)

That fixed it for me, disabling it. NancokPS2 should try it too to pinpoint issue.

I do however get
"_save_to_cache: Condition "f.is_null()" is true.
<C++ Source> drivers/gles3/shader_gles3.cpp:609 @ _save_to_cache()"
error spammed in debugger when it's disabled.

EDIT: Actually, no, that didn't fix it, it keeps doing it at times, just a bit later.

Sure keeps happening when I toogle preview light and preview environment. Those even freeze-before-glitching for a small period of time unlike 4.0.3.

[Foxysen]

I could try to bisect this issue somewhere between 4.0.0 to 4.1.0.
But it takes me 6 hours to compile Godot source code from scratch. And on additional compiles from that base I ended up having errors in Godot, ie bad compile, no idea why.

So I would need a compile buddy.

(Have AMD GPU too like these two people, Windows, will write more later)

[bitsawer]

Also possibly related issue where OpenGL rendering worked in Godot 4.0 and then stopped working in 4.1:

• Can't run Godot OpenGL 3 on ATI Radeon HD 3650 since shader cache addition #78888

This one also seems to hint at shader caching issues, although there seemed to be more problems behind it. The drivers and GPU were pretty ancient. They also did some good release bisecting, possibly pointing to some OpenGL change in 4.1 dev2: #78888 (comment) However, this is still just speculation, these issues might have nothing to do with each other.