Port Compiz to EGL (?)

[berylline]

AFAIK, Compiz uses GLX. Maybe porting it to EGL would be better, although I'm not entirely sure how this would work out yet.

Useful links:

https://mozillagfx.wordpress.com/2021/10/30/switching-the-linux-graphics-stack-from-glx-to-egl/

https://hackaday.com/2021/11/23/firefox-brings-the-fire-shifting-from-glx-to-egl/

https://utcc.utoronto.ca/~cks/space/blog/linux/EGLAndGLXAndOpenGL

https://blogs.gnome.org/gtk/2021/05/10/adventures-in-graphics-apis/

[berylline]

After doing some research, comparing EGL functions and variables with those of GLX and writing down some notes, it looks like it won't be too hard to port Compiz to EGL, although without further research and advice, I think it will still be difficult in a way(especially because I don't know how to replace all of the GLX extensions yet) and I don't think that the ideas and conceptions for the port would be 100% complete yet.

EDIT:

Another good thing to know(I think):

eglBindAPI can be used to bind to the desktop OpenGL API with EGL_OPENGL_API and, if I've read the specification for EGL_KHR_create_context correctly, you can use the aforementioned extension to request a specific version of OpenGL(or OpenGL ES) for the context that you want to create, so I think that's good to know(although I'm not sure if I'll actually implement this or if this is a good idea for what I want to do specifically).

[berylline]

Another thing:

Since Compiz uses XLib, replacing GLX with EGL can be done by using EGL with the EGL_EXT_platform_base and EGL_EXT_platform_x11 extensions.

And then when the time comes to port Compiz to XCB(whichever order that happens in), EGL_EXT_platform_x11 can be swapped in for EGL_EXT_platform_xcb, in accordance with #2 (comment).

(There's also EGL_KHR_platform_x11, but I chose the EXT extension instead of the KHR one for consistency and also for when I eventually use the equivalent EGL extension for XCB(EGL_EXT_platform_xcb), FYI.)

[berylline]

This is technically not related to EGL, but it seems like GLX_MESA_copy_sub_buffer can be replaced with GL_EXT_window_rectangles, although I'm not sure if it would be (technically) correct or sound to replace the former GLX extension with the latter OpenGL extension or not. I think I would have to ask about this possibility at some point to see if I'm correct or not.

[berylline]

See #8.