Re: [Plib-users] pui help

[Brian S. <sch...@ho...>]

>Hmmm - what's unusual about this is switching all of those GLUT function
>callbacks within a PUI callback which presumably is in turn inside one of
>those very GLUT callbacks that you're changing.
>
>I've never tried to do that kind of thing.  I'd usually have just one GLUT
>callback for each of those events - and use an 'if' statement at the start
>of the callback to make it do nothing in 'back-button' mode.   That somehow
>seems 'kinder' than switching the callbacks around all the time.
>
>So I wonder if this is some kind of a GLUT screwup.
>
>Have you tried building this application against 'freeglut' (and if you
>have - have you tried building it against the classic 'GLUT')?  There are
>several freeglut developers on this list - so it's not like I'm just trying
>to punt the problem over to someone else!
>
>I'm thinking that if somehow the return stack was being corrupted - then
>backButton->hide() would be the first thing to attempt to do a 'return',
>so it would be the thing that would show up in the crash report even though
>it is not the code with the bug in it.
>
>It's a long shot - but that's the only odd thing I can see from the
>information you've given us.
>
>The actual hide function itself is *FAR* too simple to cause this problem
>unless either the stack or the 'backButton' pointer is corrupted.
>
>You could discount the latter possibility by doing:
>
>   fprintf ( stderr, "backButton=%p\n", backButton ) ;
>
>...and sticking that in the line just below the 'new OneShot' - and again
>just before the call to 'hide()'.  If the address changes then that's
>what screwed up.  If it doesn't change then it's something else.
>
>However, this is very likely to be some kind of general memory screwup -
>which means that the odds are high that this will eventually turn out to
>be an application bug.
>
>>Unhandled exception in program.exe: 0xC0000005:  Access Violation.
>
>I don't know Windows/MSVC - but if that '0xC0000005' is a memory address
>then it's a suspiciously round number...such as you might get in the
>scenario I'm suggesting above where the return address has been screwed up.
>
>It's very hard to diagnose these things at long range.

Steve,
   I stuck in those printfs and the address did change, I'm looking through 
my program again and can't seem to find why it is doing this.  Is it because 
I am changing the GLUT callbacks inside a pui callback?  The reason I have 
different callback function is mainly for organizational purposes, I dont 
like functions that are thousands of lines long it looks messy.  As for 
Bruce's comment the button is a global variable declared in a .h file so 
that is not the problem (with VC++6 it wouldn't compile otherwise).

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