Libretro support in OpenGL/Vulkan backend

[niclashoyer]

I'm currently experimenting with rendering using the libretro API. While libretro-backend already provides a framebuffer for software based rendering, I'd like to explore what is needed to get the shared GL/Vulkan context working, but I'm a bit confused.

So as I understand now the context the examples from gfx-rs are using glutin to create the context? In the libretro scenario, the libretro frontend creates the windows and contexts and sends it over to the core. Is this basically the same direction as #2749?

[kvark]

IIRC, GL backend currently only works with glutin for the context initialization. We are open to expanding this, just nobody stepped up so far.

Other backends don't depend on either glutin or winit - they work with https://github.com/rust-windowing/raw-window-handle/ for the Surface creation. You could implement the HasRawWindowHandle trait for your window for a smooth and easy connection.