Oops, I take it back. That didn't solve the problem.
I can tell you that the access violation occurs on a pointer to an object
named Screen which seems to be in Producer.
On Wed, 25 Apr 2007, Keith Parkins wrote:
That did it.
Thanks,
-K
On Wed, 25 Apr 2007, Thrall, Bryan wrote:
Keith Parkins wrote on Wednesday, April 25, 2007 1:45 PM:
> I am a bit fuzzy on reference pointers and am not certain why the
> following is bad although I have a gut feeling as to why.
>
> I have a class Derived which is derived from base class MY_D_REF
> which is a descendant of osg::Referenced. Derived is also a direct
> decedent of osgGA::GUIEventHandler.
>
> class Derived : public MY_D_REF, public osgGA::GUIEventHandler,
> class MY_D_REF : public osg::Referenced
osgGA::GUIEventHandler also is derived from osg::Referenced, so you're
actually inheriting from that class multiple times. Try using virtual
inheritance.
>
> Class MY_D_REF has a callback which uses a this * to pack its callback
> data:
>
> trans->setUserData(this);
> trans->setUpdateCallback(new MyCallback);
>
> //---------------------------------------------------------------
> class MyCallback : public osg::NodeCallback {
> public:
> virtual void operator()(osg::Node *node, osg::NodeVisitor *nv) {
> osg::ref_ptr<MY_D_REF> wp = dynamic_cast<MY_D_REF*>
> (node->getUserData());
> /--- do stuff --/
> traverse(node, nv);
}
> When Derived is destroyed at the end of the program, I get an access
> violation (xmemory's (windoze) destructor template).
>
> IF Derived is not derived from both classes, everything is okay.
>
> or
>
> IF I take out the callback, everything is okay.
>
> When I say that everything is okay, I mean the program exits fine. I
> understand that everything is not in fact okay.
>
> Is this because of packing my callback with a this pointer and it's
> not getting its count decreased? Is that bad mojo? Is there something
> special I should be doing to decrease the reference the MY_D_REF
> object in its destructor? I have the destructors protected for the
> derived classes. Or is this a something that I might run into because
> multiple ancestors are derived from osg::Referenced? I was worried
> about a possible circular reference, so I took out reference pointers
> in the derived classes, but the results were the same.
>
> Thanks,
> Keith
HTH,
--
Keith Parkins U of R Center for Visual Science
[EMAIL PROTECTED] Meliora Hall, Room 236
office: (585) 275-3938 lab: (585) 275-2230
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