GLAD 1 creates unusable loaders for EGL, while the newly released GLAD 2
does not, so for consistency I thought that it would be a good idea to
uniform things beforehand. While it had some API changes some renames
were all that was needed and everything works like before, at least on
the Wayland branch.
I've kept the structure identical, although this new generator has quite
a few hefty features, such as a single header mode.
I've also added GLAD to `thirdparty/README.md`, but I haven't specified
that in the commit title because it's a very small "fix".
First implementation with Linux display manager.
- Add single-threaded mode for EditorResourcePreview (needed for OpenGL).
Co-authored-by: clayjohn <claynjohn@gmail.com>
Co-authored-by: Fabio Alessandrelli <fabio.alessandrelli@gmail.com>
This code currently isn't compiled (and cannot compile).
We plan to re-add OpenGL ES-based renderer(s) in Godot 4.0 alongside Vulkan
(probably ES 3.0, possibly also a low-end ES 2.0), but the code will be quite
different so it's not relevant to keep this old Godot 3.2 code.
The `drivers/gles2` code from the `3.2` branch can be used as a reference for
a potential new implementation.
