Picking

VTKExamples/Cxx/Interaction/Picking


Code

Picking.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkActor.h>
#include <vtkSphereSource.h>
#include <vtkRendererCollection.h>
#include <vtkCellArray.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkObjectFactory.h>
#include <vtkPlaneSource.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkPropPicker.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

// Handle mouse events
class MouseInteractorStyle2 : public vtkInteractorStyleTrackballCamera
{
  public:
    static MouseInteractorStyle2* New();
    vtkTypeMacro(MouseInteractorStyle2, vtkInteractorStyleTrackballCamera);

    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());

      double* pos = picker->GetPickPosition();
      std::cout << "Pick position (world coordinates) is: "
                << pos[0] << " " << pos[1]
                << " " << pos[2] << std::endl;

      std::cout << "Picked actor: " << picker->GetActor() << std::endl;
      //Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetCenter(pos[0], pos[1], pos[2]);
      sphereSource->SetRadius(0.1);

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

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


      //this->GetInteractor()->GetRenderWindow()->GetRenderers()->GetDefaultRenderer()->AddActor(actor);
      this->GetDefaultRenderer()->AddActor(actor);
      // Forward events
      vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
    }

  private:

};

vtkStandardNewMacro(MouseInteractorStyle2);

// Execute application.
int main(int, char *[])
{
  vtkSmartPointer<vtkPlaneSource> planeSource =
    vtkSmartPointer<vtkPlaneSource>::New();
  planeSource->Update();

  // Create a polydata object
  vtkPolyData* polydata = planeSource->GetOutput();

  // Create a mapper
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  mapper->SetInput ( polydata );
#else
  mapper->SetInputData ( polydata );
#endif

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

  std::cout << "Actor address: " << actor << std::endl;

  // 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 stype to use for interaction.
  vtkSmartPointer<MouseInteractorStyle2> style =
    vtkSmartPointer<MouseInteractorStyle2>::New();
  style->SetDefaultRenderer(renderer);

  renderWindowInteractor->SetInteractorStyle( style );

  // Add the actors to the scene
  renderer->AddActor ( actor );
  renderer->SetBackground ( 0,0,1 );

  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Initialize();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(Picking)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(Picking MACOSX_BUNDLE Picking.cxx )

target_link_libraries(Picking ${VTK_LIBRARIES})

Download and Build Picking

Click here to download Picking and its CMakeLists.txt file. Once the tarball Picking.tar has been downloaded and extracted,

cd Picking/build 

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./Picking

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.