Re: [gtk-vnc-devel] critical error if scaling is on

[Rob Stoddard <rstoddard telanetix com>]

It cannot be called without a prior gtkglext begin call, as far as I 
know.  If it seems to work, beware- you're walking into a trap.  Allow 
me to explain.

Gtkglext uses glXMakeCurrent in its begin function, but doesn't 
"unMakeCurrent"   by passing NULL for the context in glXMakeCurrent when 
you use gtkglext's end function.  To make a given OpenGL context not 
current, you either call glXMakeCurrent with NULL for the context or you 
make another OpenGL context current.  This is a problem if a program 
uses more than one context for rendering OpenGL and somebody (ahem) uses 
OpenGL calls without putting them into a gtkglext begin - end 
enclosure.  Obviously what will happen is the widget will work well when 
used in an example program alone, but will not play well with others.

What I suggest is that the map and unmap events be used.  I am not sure, 
whether the widget is mapped for each of these calls, but I am sure it 
is readily testable.

Regards,

Rob Stoddard


Anthony Liguori wrote:
> Jonh Wendell wrote:
> > Em Seg, 2008-06-02 às 08:00 -0700, Rob Stoddard escreveu:
> >  
> > > I would suppose you are closing that connection after removing the 
> > > widget from its parent,  or removing something higher up from its 
> > > parent?  Regardless, this type of error happens when you try to call 
> > > gdk_gl_drawable_gl_begin on a widget that's not "currently shown."
> > >
> > >
> > > Regards,
> > >
> > > Rob Stoddard
> > >     
> >
> > Thanks, Rob.
> >
> > I just committed this patch, which fixes those messages.
> >   
>
> All your patch does is causing texture leaking.  Please revert your 
> patch.  We need to come up with a better solution that doesn't 
> introduce another bug.  Perhaps we need to connect to an event that 
> occurs before the window looses visibility?
>
> Maybe glDeleteTexture can be called without doing gl_begin?
>
> Regards,
>
> Anthony Liguori
>
> > Cheers,
> >   
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