[vtkusers] MouseWheel usage with vtkInteractorStyleTerrain

[David Doria]

On Fri, Dec 11, 2009 at 7:35 PM, pof <jd379252 at gmail.com> wrote:

> Hi,
> I'm using a vtkInteractorStyleTerrain, and I would like to use the
> mousewheel to do some zoom in/out towards the scene focal point, actually
> pretty much like what is obtained using a 'L' keypress.
> I've tried to change the mousewheelfactor with SetMouseWheelFactor(2), but
> still nothing happen at rendering (i.e. the camera does not move).
> I 've obviously missed something. Does anybody has an idea ?
> Thanks
> Pof
>
>
You can subclass the interactor and change any behaviors you like. Here,
you'd be interested in OnMouseWheelForward and OnMouseWheelBackward

Here is a demo:

#include <vtkSmartPointer.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkInteractorStyleTerrain.h>
#include <vtkObjectFactory.h>

class MyInteractorStyle : public vtkInteractorStyleTerrain
{
  public:
    static MyInteractorStyle* New();

    virtual void OnMouseWheelForward()
    {
      cout << "Wheel forward" << endl;

        vtkRenderWindowInteractor *rwi = this->Interactor;

      this->FindPokedRenderer(rwi->GetEventPosition()[0],
                              rwi->GetEventPosition()[1]);
      this->CreateLatLong();
      if (this->LatLongLines)
        {
        this->LatLongLinesOff();
        }
      else
        {
        double bounds[6];
        this->CurrentRenderer->ComputeVisiblePropBounds( bounds );
        double radius = sqrt((bounds[1]-bounds[0])*(bounds[1]-bounds[0]) +
                             (bounds[3]-bounds[2])*(bounds[3]-bounds[2]) +
                             (bounds[5]-bounds[4])*(bounds[5]-bounds[4]))
/2.0;
        this->LatLongSphere->SetRadius( radius );
        this->LatLongSphere->SetCenter((bounds[0]+bounds[1])/2.0,
                                       (bounds[2]+bounds[3])/2.0,
                                       (bounds[4]+bounds[5])/2.0);
        this->LatLongLinesOn();
        }
      this->SelectRepresentation();
      rwi->Render();

      // forward events
      vtkInteractorStyleTerrain::OnMouseWheelForward();
    }

    virtual void OnMouseWheelBackward()
    {
      cout << "Wheel backward" << endl;

      // forward events
      vtkInteractorStyleTerrain::OnMouseWheelBackward();
    }

};
vtkStandardNewMacro(MyInteractorStyle);

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

  vtkSmartPointer<vtkSphereSource> sphereSource =
      vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->Update();

  //create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper =
      vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());

  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(1,1,1); // Background color white

  renderWindow->Render();

 // vtkSmartPointer<vtkInteractorStyleTerrain> style =
   //   vtkSmartPointer<vtkInteractorStyleTerrain>::New();

  vtkSmartPointer<MyInteractorStyle> style =
    vtkSmartPointer<MyInteractorStyle>::New();

  renderWindowInteractor->SetInteractorStyle( style );

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

Thanks,

David
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