[vtkusers] vtk actor inheritance

Wed May 5 07:13:42 EDT 2004

Hi!

On 04.05.2004, at 16:19, Simon DROUIN wrote:

> I had the same problem.

Same for me... Trying to make an actor class which can hold an  
additional int for an ID. Seems like a lot of people need to do  
something like that and it's not covered in the book in detail... :( So  
maybe somebody who already did that and it worked could write a howto  
or something?
I wasn't sure if it was better to start a new thread for this but  
because it's basically the same problem I posted to this thread.

> There is probably a more elegant solution using factories, but I  
> haven't tried it.

Hm, I use vtk with qt and tried to derive a factory like it's described  
in the book. But my actors aren't shown either. I'm not sure if I have  
to derive from vtkActor or vtkOpenGLActor either...

I extended  vtkFactory _and_ vtkActor because the book said so. That's  
a lot of code for adding an int to a class...

This is my code, maybe someone can say what I did wrong so maybe all of  
us could use it then...? It compiles but no actors are shown and at the  
end of exectution (when I quit the qt Application) it segfaults.

vtkMyFactory.h:

################################################################ Begin  
of file
#ifndef OBJF_H
#define OBJF_H
#include <vtkObjectFactory.h>
#endif

#include <vtkMyActor.h>

class vtkMyFactory : public vtkObjectFactory {

    public:
      vtkMyFactory();
      virtual const char* GetVTKSourceVersion();
      virtual const char* GetDescription();

};

################################################################ End of  
file

vtkMyFactory.cc:

################################################################ Begin  
of file
#include "vtkMyFactory.h"
#include "vtkVersion.h"

VTK_CREATE_CREATE_FUNCTION(vtkMyActor);

VTK_FACTORY_INTERFACE_IMPLEMENT(vtkMyFactory);

vtkStandardNewMacro(vtkMyFactory);

vtkMyFactory::vtkMyFactory() {

    this->RegisterOverride("vtkActor", "vtkMyActor", "vtkActor with ID",  
1,
                           vtkObjectFactoryCreatevtkMyActor);

}

const char* vtkMyFactory::GetVTKSourceVersion() {
    return VTK_SOURCE_VERSION;
}

const char* vtkMyFactory::GetDescription() {
    return "Factory needed to extend vtkActor by and int ID...";
}

################################################################ End of  
file

vtkMyActor.h:

################################################################ Begin  
of file
#include <vtkActor.h>

class vtkMyActor : public vtkActor {
    public:
       vtkMyActor();
       int GetID();
       void SetID(int id);
       static vtkMyActor* New();

    private:
       int id;         // id of this glyph's actor

};

################################################################ End of  
file

vtkMyActor.cc:

################################################################ Begin  
of file
#include "vtkMyActor.h"

#ifndef OBJF_H
#define OBJF_H
#include <vtkObjectFactory.h>
#endif

#include "vtkSetGet.h"

vtkMyActor::vtkMyActor() {
    this->id = -1;
}

int vtkMyActor::GetID() {
    return this->id;
}

void vtkMyActor::SetID(int id) {
    this->id = id;
}

vtkStandardNewMacro(vtkMyActor);
################################################################ End of  
file

vtkStandardNewMacro is defined in vtkSetGet.h...

GUI.cc (which is called by my main method because it's a QWidget- I  
omitted the includes and unrelevant stuff) holds

#######
GUI::GUI(QWidget* parent, const char* name) : QWidget(parent,name) {

vtkObjectFactory::RegisterFactory((vtkObjectFactory*)vtkMyFactory:: 
New());
    vtkQtObjectFactory::RegisterObjectFactory();

   ...

   # All Actors are added to the renderer with ren->AddActor(actor);

   ...

}

#######

That stuff already worked/showed Actors for the code I posted earlier  
on this mailing list, so the error is definitely in the definion of the  
vtkMyActors. Back then I inherited from vtkActor directly overwriting  
the New method and it _showed_ the actors.

I also ran valgrind ( a memory leak checker) on the program that held  
of the code above and it gave me this many times - I don't know what  
happens, but the int is not allocated I think:

==521== Invalid read of size 4
==521==    at 0x40AD5FD7:  
vtkObjectFactory::RegisterFactory(vtkObjectFactory*) (in /usr/lib/libvt
==521==    by 0x805D312: GUI::GUI(QWidget*, char const*) (in  
/home/goya/glyphview/Tests/GlyphWrap
==521==    by 0x805EA98: main (in  
/home/goya/glyphview/Tests/GlyphWrapper-Test/GUI)
==521==  Address 0x450FAFF0 is not stack'd, malloc'd or free'd

...and this:

==521== Invalid read of size 4
==521==    at 0x40AD4E92: vtkObjectBase::PrintHeader(std::ostream&,  
vtkIndent) (in /usr/lib/libvt
==521==    by 0x405A2DCC: vtkRenderer::Render() (in  
/usr/lib/libvtkRendering.so.4.2.4)
==521==    by 0x405AA521: vtkRendererCollection::Render() (in  
/usr/lib/libvtkRendering.so.4.2.4)
==521==    by 0x4059875D: vtkRenderWindow::DoStereoRender() (in  
/usr/lib/libvtkRendering.so.4.2.4

==521== Invalid read of size 4
==521==    at 0x40AAB4B2: operator<<(std::ostream&, vtkIndent const&)  
(in /usr/lib/libvtkCommon.s
==521==    by 0x40AD4EB7: vtkObjectBase::PrintHeader(std::ostream&,  
vtkIndent) (in /usr/lib/libvt
==521==    by 0x405A2DCC: vtkRenderer::Render() (in  
/usr/lib/libvtkRendering.so.4.2.4)
==521==    by 0x405AA521: vtkRendererCollection::Render() (in  
/usr/lib/libvtkRendering.so.4.2.4)
==521==  Address 0x4 is not stack'd, malloc'd or free'd

==521== Process terminating with default action of signal 11 (SIGSEGV):  
dumping core
==521==  Address not mapped to object at address 0x4
==521==    at 0x40AAB4B2: operator<<(std::ostream&, vtkIndent const&)  
(in /usr/lib/libvtkCommon.s
==521==    by 0x40AD4EB7: vtkObjectBase::PrintHeader(std::ostream&,  
vtkIndent) (in /usr/lib/libvt
==521==    by 0x405A2DCC: vtkRenderer::Render() (in  
/usr/lib/libvtkRendering.so.4.2.4)
==521==    by 0x405AA521: vtkRendererCollection::Render() (in  
/usr/lib/libvtkRendering.so.4.2.4)

...and in the leak summary:

==521== 24 bytes in 1 blocks are definitely lost in loss record 137 of  
449
==521==    at 0x4002F202: operator new(unsigned)  
(vg_replace_malloc.c:162)
==521==    by 0x40AD2E45: vtkObject::New() (in  
/usr/lib/libvtkCommon.so.4.2.4)
==521==    by 0x805D30A: GUI::GUI(QWidget*, char const*) (in  
/home/goya/glyphview/Tests/GlyphWrap
==521==    by 0x805EA98: main (in  
/home/goya/glyphview/Tests/GlyphWrapper-Test/GUI)
==521==
==521==
==521== 48 bytes in 1 blocks are definitely lost in loss record 207 of  
449
==521==    at 0x4002F202: operator new(unsigned)  
(vg_replace_malloc.c:162)
==521==    by 0x412BAD0C: (within /usr/lib/libqt-mt.so.3.2.3)
==521==    by 0x412BD26A: QGLWidget::setContext(QGLContext*, QGLContext  
const*, bool) (in /usr/li
==521==    by 0x412BCED5: QGLWidget::init(QGLContext*, QGLWidget  
const*) (in /usr/lib/libqt-mt.so

I didn't post everything from the valgrind output because it would make  
this post even bigger, but I hope I got the important parts of it.

Does anyone have an idea what's wrong? Maybe someone with knowledge of  
the things that vtk does internally...
I would be really really thankful and maybe it helps others out there  
too if we manage to get a working derivation of a vtkActor...

Ciao!
    Wiebke