Not only does this fix macOS 10.14 ("Mojave")'s broken NSOpenGLCPSwapInterval
support, it also lets us implement "adaptive vsync" on macOS!
CVDisplayLink is supported back to macOS 10.4 ("Tiger"), so we just use it
universally without version checks and dump NSOpenGLCPSwapInterval, Mojave or
not.
Andrey
Seems latest google angle library successfully built & tested under macOS'es.
https://github.com/google/angle
We need to use GLES2 to implement true cross-platform code.
This is often useful for SDL apps that aren't meant to be games: the
integrated GPU starts up faster, uses less power, and is often more than
fast enough.
Note that even with this change, the app will still default to the more
powerful, discrete GPU if one is available; an app that prefers the integrated
GPU will still need the NSSupportsAutomaticGraphicsSwitching key properly
set in its Info.plist and Mac OS X 10.7 or later.
https://developer.apple.com/library/mac/qa/qa1734/_index.html
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
