Crash When Running opengl_texture Example on Windows — FemtoVG Panic

[metahead00]

Hi! I'm trying to run the opengl_texture example from the Slint repo on Windows, using C++ and GLEW, but I'm having trouble getting any output — the window stays blank and exits in a second., even though the app gets build with no problem. The message I get is:

thread '<unnamed>' panicked at \opengl_texture\build\_deps\slint-src\internal\renderers\femtovg\lib.rs:267:68:
called `Option::unwrap()` on a `None` value

I replaced gles with glew and tried setting different backends, but the other renderers (e.g. software) are unrecognized and it seems to fall back to FemtoVG, which crashes. Is this a known issue on Windows? Or am I missing some config or build flag? I just want to play a 3D animation in a Slint-based app. Any advice or working setups would be appreciated!

Thanks in advance

[tronical]

Ouch, that's a bug. I can reproduce this on Linux. This appears to affect only the C++ build of the example, the Rust one works fine. I've filed #8901 and will look into it.

[tronical]

Ok, I've found it. The issue is that with C++ we accidentally enabled the WGPU renderer by default, which doesn't use OpenGL. With Rust the backend selector prevents this from becoming a choice, but we've also got our defaults wrong. I'll fix that. Meanwhile, there are two different ways how you can solve this:

• pass -DSLINT_FEATURE_RENDERER_FEMTOVG_WGPU=OFF to cmake
• or set SLINT_BACKEND=winit-femtovg