On Tuesday 17 December 2013 01:21:14 Thiago Macieira wrote:
> On terça-feira, 17 de dezembro de 2013 09:49:48, Yves Bailly wrote:
> > (1)
> > When I try to build this program, I get a link error:
> > gl_widget.obj : error LNK2019: symbole externe non résolu "protected: bool
> > __cdecl QAbstractOpenGLFunctions::isInitialized(void)const "
> > (?isInitialized@QAbstractOpenGLFunctions@@IEBA_NXZ) référencé dans la
> > fonction "protected: virtual void __cdecl Gl_Widget::initializeGL(void)"
> > (?initializeGL@Gl_Widget@@MEAAXXZ)
> >
> > ...which basically says the external symbol
> > QAbstractOpenGLFunctions::isInitialized() could not be resolved.
> > If I remove the "if" line, thus not calling isInitialized(), everything
> > works fine. I even tried to force name resolution with "if (not
> > this->QOpenGLFunctions_3_3_Core::isInitialized())", but no luck.
> >
> > Any idea about what can go wrong?
>
> Yes: you're calling a function that is not public. Stop calling
> isInitialized().
>
> > To alleviate those points, I tried something like this (with various
> > variations and more sanity checks):
> >
> > class My_Class: public
> > Some_Other_Super, protected QOpenGLFunctions_3_3_Core {
> >
> > void some_init_method()
> > {
> >
> > QOpenGLContext* ctx = QOpenGLContext::currentContext();
> > QOpenGLFunctions_3_3_Core* funcs =
> >
> > ctx->versionFunctions<QOpenGLFunctions_3_3_Core>();
> > dynamic_cast<QOpenGLFunctions_3_3_Core&>(*this) = *funcs;
> >
> > }
> >
> > }
>
> Why are you trying to initialize like that? You should simply call
> initializeOpenGLFunctions().
Yes, what Thiago said is correct. Don't be shy about calling this function as
it's basically a no-op if it has already been called before.
If you're planning on using the functions object in more than one class you
may be better off obtaining a pointer to it from the
QOpenGLContext::versionFunctions<QOpenGLFunctions_3_3_Core>() function rather
than sub-classing. The object is owned by the context and is shared which is
less overhead than having multiple classes of your own all of which subclass.
Cheers,
Sean
ps I'm looking to add support for OpenGL 4.4 but this requires rewriting the
spec parser used to generate these classes as Khronos has now switched from
the legacy .spec files to an XML format. Also I need a 4.4 capable GPU... ;)
--
Dr Sean Harmer | [email protected] | Managing Director UK
Klarälvdalens Datakonsult AB, a KDAB Group company
Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
KDAB - Qt Experts - Platform-independent software solutions
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