Finish OpenGL rendering by external OpenGL code, prepare 2D drawing into window
This is the counterpart to Screen(‘BeginOpenGL’). Whenever you used
Screen(‘BeginOpenGL’) to enable external OpenGL drawing from Matlab, you *must*
call Screen(‘EndOpenGL’) when you’re finished with a window, either because you
want to draw into a different window, or you want to use a Screen command.
Psychtoolbox will abort your script if you omit this command.