VTK 6.1 and Qt 5.3: 3D Objects in QVTKWidget with bad transparencies

Question

Base: Debian 7.5 Wheezy 64 bits - Qt 5.3 installed from Online Installer; VTK 6.1 successfully compiled and installed manually with Qt support.

Result: A 3D sphere is displayed in a 3D QVTK window. At first glance, It looks OK, but when sphere is rotated, several panels and parts of the sphere become transparent.

Description:

Tried the basic official example of VTK for Qt:

In main.cpp:

#include <QApplication>

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL);
VTK_MODULE_INIT(vtkInteractionStyle);

#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkImageViewer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleImage.h>
#include <vtkRenderer.h>
#include <vtkJPEGReader.h>
#include <QVTKWidget.h>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QVTKWidget widget;
      widget.resize(256,256);

      // Setup sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
          vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();
      vtkSmartPointer<vtkPolyDataMapper> sphereMapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      sphereMapper->SetInputConnection(sphereSource->GetOutputPort());
      vtkSmartPointer<vtkActor> sphereActor =
          vtkSmartPointer<vtkActor>::New();
      sphereActor->SetMapper(sphereMapper);

      // Setup window
      vtkSmartPointer<vtkRenderWindow> renderWindow =
          vtkSmartPointer<vtkRenderWindow>::New();

      // Setup renderer
      vtkSmartPointer<vtkRenderer> renderer =
          vtkSmartPointer<vtkRenderer>::New();
      renderWindow->AddRenderer(renderer);

      renderer->AddActor(sphereActor);
      renderer->ResetCamera();

      widget.SetRenderWindow(renderWindow);
      widget.show();

    return a.exec();
}

And significantly, RenderWindowUISingleInheritance gives same result.

---

SOLUTION

The final code stands as follows:

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL);
VTK_MODULE_INIT(vtkInteractionStyle);

#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkImageViewer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleImage.h>
#include <vtkRenderer.h>
#include <vtkJPEGReader.h>
#include <QVTKWidget.h>
#include <vtkProperty.h>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QVTKWidget widget;
      widget.resize(256,256);

      // Setup sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
          vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();
      vtkSmartPointer<vtkPolyDataMapper> sphereMapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      sphereMapper->SetInputConnection(sphereSource->GetOutputPort());
      vtkSmartPointer<vtkActor> sphereActor =
          vtkSmartPointer<vtkActor>::New();
      sphereActor->GetProperty()->SetFrontfaceCulling(true);
      sphereActor->SetMapper(sphereMapper);

      // Setup window
      vtkSmartPointer<vtkRenderWindow> renderWindow =
          vtkSmartPointer<vtkRenderWindow>::New();

      // Setup renderer
      vtkSmartPointer<vtkRenderer> renderer =
          vtkSmartPointer<vtkRenderer>::New();
      renderWindow->AddRenderer(renderer);

      renderer->AddActor(sphereActor);
      renderer->ResetCamera();

      widget.SetRenderWindow(renderWindow);
      widget.show();

    return a.exec();
}

Note the additions of:

#include <vtkProperty.h>

and

sphereActor->GetProperty()->SetFrontfaceCulling(true);

Answer 1

Looks like Frontface culling is off by default. Try adding sphereActor->GetProperty()->FrontfaceCullingOn();