[HOpenGL] Re: Exiting gracefully from (H)GLUT?

[Sven Panne]

C. Reinke wrote:
> >     Issue OpenGL calls *after* the first createWindow, never before.
> 
> Isn't that an argument against the displayFunc parameter to HOpenGL's
> createWindow? One could still have a createSimpleWindow or something
> for simple applications, but why pass and install a null handler if
> one most certainly needs to replace it soon?

This would break the current API, so I'd vote against such a change for
HOpenGL 1.x, but I'm open for suggestions for an additional function
(OK, this *could* break applications, too, but it's much less likely).
I would propose to leave createWindow as it is and add:

   createWindow' :: String -> [DisplayMode]
                 -> Maybe WindowPosition -> Maybe WindowSize
                 -> IO Window

Any comments?

> I was fooled by display lists [...]

Who wasn't?  :-}  It has been a little bit unclear to me for a long
time (and obviously other people, too) that creating a GLUT window or
an overlay effectively creates a new OpenGL state machine and you start
with none at all. A look in the GLX spec was helpful...

[ exitWith vs. shutdownHaskellAndExit vs. hs_exit ]

To keep easy backwards compatibility, the GLUT module will contain
wrappers/re-implementations for GHC's currently faulty (IMHO) functions
from System, so you can issue

   exitWith ExitSuccess

without getting a cryptic RTS message. A new compatibility release of
HOpenGL will be released very soon, I'm just in the middle of fighting a
number of small issues regarding different compilers, OpenGL implementations,
OS variations, etc. *sigh*

Cheers,
   S.