[osg-users] Crash in Camera::setRenderer()

Robert Osfield robert.osfield at gmail.com
Tue Jun 9 05:16:08 PDT 2015

Hi Nicolas,

Are you using C pointers or ref_ptr<> when keeping reference around
the to the slave Camera?  If you use a C* pointer then there is good
chance that the reference count on the Camera is going to zero when
it's removed from the View and getting deleted, then you add that
dangling pointer back to the View and bang your get a crash there

That's my best guess given I don't have any code in front of me.


On 9 June 2015 at 13:00, Nicolas Baillard <nicolas.baillard at gmail.com> wrote:
> Hello everyone.
> In my application I create several views and several cameras. Upon user interaction each camera can be added or removed from a view using View::addSlave() and View::removeSlave().
> My code ensures that each camera is only assigned to only one view at a time. A camera can't be assigned to another view before being removed from the view it currently is.
> When I do that I often get a crash in the Camera::setRenderer() method that is called by addSlave().
> The crash happen into GraphicsOperation destructor. When a camera is added to a view with addSlave() a new renderer is created for it. If the camera already has a renderer that renderer is automatically deleted by the reference counting pointer. That's when the crash happen. It looks like the renderer (or maybe one of its members) is deleted twice.
> I'm not using multithreading. I don't change camera assignation during rendering with callbacks. Camera assignation is all done outside of the CompositeViewer::frame() method.
> Do you have any idea what might be causing this crash ?
> Regards,
> Nicolas
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=64003#64003
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