VTK之交互方式（interactor style）

    VTK提供了多種交互方式，最常用的包括joystick和trackball，並且可以分別對actor和camera進行操作。

    在VTK中，可以通過集成已有的交互方式類，然後添加自己的功能，則可以完成在觸發響應時，完成響應的操作。

    以下是自定義交互方式類的一個實例。該實例實現的是對鼠標點擊的物體進行高亮顯示。

   

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkMath.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkSphereSource.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkObjectFactory.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkPropPicker.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
 
// Handle mouse events
class MouseInteractorHighLightActor : public vtkInteractorStyleTrackballCamera
{
public:
  static MouseInteractorHighLightActor* New();
  vtkTypeMacro(MouseInteractorHighLightActor, vtkInteractorStyleTrackballCamera);
 
  MouseInteractorHighLightActor()
  {
    LastPickedActor = NULL;
    LastPickedProperty = vtkProperty::New();
  }
  virtual ~MouseInteractorHighLightActor()
  {
    LastPickedProperty->Delete();
  }
  virtual void OnLeftButtonDown()
  {
    int* clickPos = this->GetInteractor()->GetEventPosition();
 
    // Pick from this location.
    vtkSmartPointer<vtkPropPicker>  picker =
      vtkSmartPointer<vtkPropPicker>::New();
    picker->Pick(clickPos[0], clickPos[1], 0, this->GetDefaultRenderer());
 
    // If we picked something before, reset its property
    if (this->LastPickedActor)
      {
      this->LastPickedActor->GetProperty()->DeepCopy(this->LastPickedProperty);
      }
    this->LastPickedActor = picker->GetActor();
    if (this->LastPickedActor)
      {
      // Save the property of the picked actor so that we can
      // restore it next time
      this->LastPickedProperty->DeepCopy(this->LastPickedActor->GetProperty());
      // Highlight the picked actor by changing its properties
      this->LastPickedActor->GetProperty()->SetColor(1.0, 0.0, 0.0);
      this->LastPickedActor->GetProperty()->SetDiffuse(1.0);
      this->LastPickedActor->GetProperty()->SetSpecular(0.0);
      }
 
    // Forward events
    vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
  }
 
private:
  vtkActor    *LastPickedActor;
  vtkProperty *LastPickedProperty;
};
 
vtkStandardNewMacro(MouseInteractorHighLightActor);
 
// Execute application.
int main(int argc, char *argv[])
{
  int numberOfSpheres = 10;
  if (argc > 1)
    {
    numberOfSpheres = atoi(argv[1]);
    }
  // 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 );
 
  // Set the custom type to use for interaction.
  vtkSmartPointer<MouseInteractorHighLightActor> style =
    vtkSmartPointer<MouseInteractorHighLightActor>::New();
  style->SetDefaultRenderer(renderer);
 
  renderWindowInteractor->SetInteractorStyle( style );
 
  for (int i = 0; i < numberOfSpheres; ++i)
    {
    vtkSmartPointer<vtkSphereSource> source =
      vtkSmartPointer<vtkSphereSource>::New();
    double x, y, z, radius;
    x = vtkMath::Random(-5,5);
    y = vtkMath::Random(-5,5);
    z = vtkMath::Random(-5,5);
    radius = vtkMath::Random(.5, 1.0);
    source->SetRadius(radius);
    source->SetCenter(x, y, z);
    source->SetPhiResolution(11);
    source->SetThetaResolution(21);
    vtkSmartPointer<vtkPolyDataMapper> mapper =
      vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputConnection ( source->GetOutputPort());
    vtkSmartPointer<vtkActor> actor =
      vtkSmartPointer<vtkActor>::New();
    actor->SetMapper ( mapper );
    double r, g, b;
    r = vtkMath::Random(.4, 1.0);
    g = vtkMath::Random(.4, 1.0);
    b = vtkMath::Random(.4, 1.0);
    actor->GetProperty()->SetDiffuseColor(r, g, b);
    actor->GetProperty()->SetDiffuse(.8);
    actor->GetProperty()->SetSpecular(.5);
    actor->GetProperty()->SetSpecularColor(1.0,1.0,1.0);
    actor->GetProperty()->SetSpecularPower(30.0);
    renderer->AddActor ( actor );
    }
 
  renderer->SetBackground ( .3, .4, .5 );
 
  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Initialize();
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}

    在VTK的示例中，對常用的交互方式，以及常用的自定義交互方式都進行了實現，各個示例的源碼地址如下：

   

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/MoveAGlyph

http://www.itk.org/Wiki/VTK/Examples/Cxx/Interaction/Game

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/TrackballActor

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/SelectAnActor

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Picking/HighlightPickedActor

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/Picking

http://stackoverflow.com/questions/27628493/vtk-interacting-with-multiple-objects

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/StyleSwitch