macOS is the only platform where desktop OpenGL is used. To support
foreign ANGLE contexts add a setting to override Gio's selection of
OpenGL implementation.
The bulk of this change is making all function pointers per-context
instead of global, and loading the OpenGL library dynamically. As a side
effect we're closer to Gio tolerating a platform without any OpenGL
implementation. For example, Apple has deprecated OpenGL and OpenGL ES
on its platforms and may remove them in the future.
Note that as a side-effect of this change, Gio needs Go 1.16 or newer to
run on iOS.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
We're about to load OpenGL function pointers into gl.Function structs.
Make sure iOS internally uses the NewFunctions constructor, not just
new(Functions).
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Package wm (for "window manager") is a better fit for the package, and
distinguishes it from the low-level package windows for the Windows API.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur