Add support for EGL on Linux #74
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| // already loaded either EGL or GLX and we want to use the same one. | ||
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| if (is_library_loaded("libEGL.so.1", &libegl) || | ||
| is_library_loaded("libGLX.so.0", &libglx)) { |
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What's the purpose of this libGLX check? Is it just an alternative to using GLX via libGL? (And if so, why is it being checked with libEGL instead of below with libGL?)
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Yes, it's an alternative to libGL.
On modern Linux systems there are two ways to load GLX:
- The new GLVND way: load GLX from libGLX and OpenGL from libOpenGL.
- The legacy way: load both GLX and OpenGL from libGL. On modern systems this just routes calls to libOpenGL or libGLX (or
libGLdispatch, but that's a GLVND implementation detail).
See the GLVND README and OpenGL ABI probosal that it links to for more information.
The reason the check is here is because if we load libGLX we also have to load libOpenGL, same as with libEGL. If libEGL is found the condition will short-circuit and it won't check for libGLX, otherwise it will check for libGLX. Inside the conditional body exactly one of libegl or libglx will be non-null. Either way we'll want to attempt to load libOpenGL to complete the EGL/GLX + OpenGL pairing.
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Apparently I forgot to respond, thanks for the explanation!
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Merged, thanks for working on this. |
GLX is a X11-specific API. EGL is an alternative that is supported under both X11 and Wayland. GL3W should remove its dependency on GLX as the Linux desktop transitions to Wayland.
This attempts to use whichever library is already loaded so that it will match your windowing library (SDL/glut/glfw/etc), but if one of them isn't already loaded it falls back to EGL or the legacy libGL implementation.
I tested it with
glut_testandglfw_testand it worked (glfw's Wayland implementation does randomly segfault on exit sometimes, but that seems unrelated...).