[vtkusers] fix position of vtkAxesActor

[Bill Lorensen]

The widget only exists during the scope of displayAxes unless another
object increases the ref count of the widget's pointer. In your case,
the ref count of widget.GetPointer() remains at 1 throughout
displayAxes. When displayAxes returns, widget is destroyed along with
widget's pointer. On the other hand, axes' pointer ref count is
increment by 1 with the statement:
 widget->SetOrientationMarker( axes );
so even though the SmartPointer axes is deleted, the axes.GetPointer()
is not destroyed on return.

One option is to pass in a reference to the widget.

See below:

#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkOrientationMarkerWidget.h>
#include <vtkAxesActor.h>
#include <vtkPropAssembly.h>
#include <vtkSmartPointer.h>


void displayAxes(vtkSmartPointer<vtkOrientationMarkerWidget> &widget,
                 vtkRenderWindowInteractor *renderWindowInteractor)
{
    vtkSmartPointer<vtkAxesActor> axes =
        vtkSmartPointer<vtkAxesActor>::New();

    widget->SetOutlineColor( 0.9300, 0.5700, 0.1300 );
    widget->SetOrientationMarker( axes );
    widget->SetInteractor( renderWindowInteractor );
    widget->SetViewport( 0.0, 0.0, 0.4, 0.4 );
    widget->SetEnabled( 1 );
    widget->InteractiveOn();
}



int main (int, char *[])
{
    vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
    sphereSource->SetCenter(0.0, 0.0, 0.0);
    sphereSource->SetRadius(1.0);
    sphereSource->Update();

    vtkPolyData* polydata = sphereSource->GetOutput();

    // Create a mapper
    vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInput(polydata);

    // Create an actor
    vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);

    // A renderer and render window
    vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
    vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
    renderWindow->AddRenderer(renderer);

    // An interactor
    vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
    renderWindowInteractor->SetRenderWindow(renderWindow);

    // Add the actors to the scene
    renderer->AddActor(actor);
    renderer->SetBackground(.2, .3, .4);

    vtkSmartPointer<vtkOrientationMarkerWidget> widget =
        vtkSmartPointer<vtkOrientationMarkerWidget>::New();
    displayAxes(widget, renderWindowInteractor);

    // Render the scene
    renderer->ResetCamera();
    renderWindow->Render();

    // Begin mouse interaction
    renderWindowInteractor->Start();

    return EXIT_SUCCESS;
}