Call SDL_RenderPresent after calling SDL_RenderReadPixels.
From "include/SDL_render.h":
"If you're using this on the main rendering target, it should be called after rendering and before SDL_RenderPresent()."
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().
Sylvain
Ryan C. Gordon
Erik Yuzwa
Philipp Wiesemann