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PointPicker

vtk-examples/Cxx/Interaction/PointPicker


Description

This example demonstrates how to get the closest point in the data set to the mouse click.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

PointPicker.cxx

#include <vtkActor.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkObjectFactory.h>
#include <vtkPointPicker.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkRendererCollection.h>
#include <vtkSphereSource.h>

namespace {

// Define interaction style
class MouseInteractorStylePP : public vtkInteractorStyleTrackballCamera
{
public:
  static MouseInteractorStylePP* New();
  vtkTypeMacro(MouseInteractorStylePP, vtkInteractorStyleTrackballCamera);

  virtual void OnLeftButtonDown() override
  {
    std::cout << "Picking pixel: " << this->Interactor->GetEventPosition()[0]
              << " " << this->Interactor->GetEventPosition()[1] << std::endl;
    this->Interactor->GetPicker()->Pick(this->Interactor->GetEventPosition()[0],
                                        this->Interactor->GetEventPosition()[1],
                                        0, // always zero.
                                        this->Interactor->GetRenderWindow()
                                            ->GetRenderers()
                                            ->GetFirstRenderer());
    double picked[3];
    this->Interactor->GetPicker()->GetPickPosition(picked);
    std::cout << "Picked value: " << picked[0] << " " << picked[1] << " "
              << picked[2] << std::endl;
    // Forward events
    vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
  }
};

vtkStandardNewMacro(MouseInteractorStylePP);

} // namespace

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->Update();

  vtkNew<vtkPointPicker> pointPicker;

  // Create a mapper and actor
  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(sphereSource->GetOutputPort());
  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());

  // Create a renderer, render window, and interactor
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("PointPicker");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetPicker(pointPicker);
  renderWindowInteractor->SetRenderWindow(renderWindow);

  vtkNew<MouseInteractorStylePP> style;
  renderWindowInteractor->SetInteractorStyle(style);

  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

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

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(PointPicker)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping PointPicker: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(PointPicker MACOSX_BUNDLE PointPicker.cxx )
  target_link_libraries(PointPicker PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(PointPicker MACOSX_BUNDLE PointPicker.cxx )
  target_link_libraries(PointPicker PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS PointPicker
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build PointPicker

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

cd PointPicker/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:

./PointPicker

WINDOWS USERS

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