ExtractSelection

VTKExamples/Cxx/PolyData/ExtractSelection


Description

This example creates 50 random points and extracts 10 of them (the points with ids 10-19).

Other Languages

See (Python)

Code

ExtractSelection.cxx

#include <vtkDataSetMapper.h>
#include <vtkExtractSelection.h>
#include <vtkIdTypeArray.h>
#include <vtkInformation.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPointSource.h>
#include <vtkPolyData.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSelection.h>
#include <vtkSelectionNode.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkUnstructuredGrid.h>
#include <vtkVertexGlyphFilter.h>

#include <array>

int main(int, char *[])
{

  vtkNew<vtkNamedColors> colors;

  std::array<double, 4> bkgL = {{0.6, 0.5, 0.4, 1.0}};
  std::array<double, 4> bkgC = {{0.3, 0.1, 0.4, 1.0}};
  std::array<double, 4> bkgR = {{0.4, 0.5, 0.6, 1.0}};
  colors->SetColor("leftBkg", bkgL.data());
  colors->SetColor("centreBkg", bkgC.data());
  colors->SetColor("rightBkg", bkgR.data());

  vtkSmartPointer<vtkPointSource> pointSource =
      vtkSmartPointer<vtkPointSource>::New();
  pointSource->SetNumberOfPoints(50);
  pointSource->Update();

  std::cout << "There are " << pointSource->GetOutput()->GetNumberOfPoints()
            << " input points." << std::endl;

  vtkSmartPointer<vtkIdTypeArray> ids = vtkSmartPointer<vtkIdTypeArray>::New();
  ids->SetNumberOfComponents(1);

  // Set values
  for (unsigned int i = 10; i < 20; i++) {
    ids->InsertNextValue(i);
  }

  vtkSmartPointer<vtkSelectionNode> selectionNode =
      vtkSmartPointer<vtkSelectionNode>::New();
  selectionNode->SetFieldType(vtkSelectionNode::POINT);
  selectionNode->SetContentType(vtkSelectionNode::INDICES);
  selectionNode->SetSelectionList(ids);

  vtkSmartPointer<vtkSelection> selection =
      vtkSmartPointer<vtkSelection>::New();
  selection->AddNode(selectionNode);

  vtkSmartPointer<vtkExtractSelection> extractSelection =
      vtkSmartPointer<vtkExtractSelection>::New();

  extractSelection->SetInputConnection(0, pointSource->GetOutputPort());
  extractSelection->SetInputData(1, selection);
  extractSelection->Update();

  // In selection
  vtkSmartPointer<vtkUnstructuredGrid> selected =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  selected->ShallowCopy(extractSelection->GetOutput());

  std::cout << "There are " << selected->GetNumberOfPoints()
            << " points in the selection." << std::endl;
  std::cout << "There are " << selected->GetNumberOfCells()
            << " cells in the selection." << std::endl;

  // Get points that are NOT in the selection
  selectionNode->GetProperties()->Set(vtkSelectionNode::INVERSE(),
                                      1); // invert the selection
  extractSelection->Update();

  vtkSmartPointer<vtkUnstructuredGrid> notSelected =
      vtkSmartPointer<vtkUnstructuredGrid>::New();
  notSelected->ShallowCopy(extractSelection->GetOutput());

  std::cout << "There are " << notSelected->GetNumberOfPoints()
            << " points NOT in the selection." << std::endl;
  std::cout << "There are " << notSelected->GetNumberOfCells()
            << " cells NOT in the selection." << std::endl;

  vtkSmartPointer<vtkDataSetMapper> inputMapper =
      vtkSmartPointer<vtkDataSetMapper>::New();
  inputMapper->SetInputConnection(pointSource->GetOutputPort());
  vtkSmartPointer<vtkActor> inputActor = vtkSmartPointer<vtkActor>::New();
  inputActor->SetMapper(inputMapper);

  vtkSmartPointer<vtkDataSetMapper> selectedMapper =
      vtkSmartPointer<vtkDataSetMapper>::New();
  selectedMapper->SetInputData(selected);

  vtkSmartPointer<vtkActor> selectedActor = vtkSmartPointer<vtkActor>::New();
  selectedActor->SetMapper(selectedMapper);

  vtkSmartPointer<vtkDataSetMapper> notSelectedMapper =
      vtkSmartPointer<vtkDataSetMapper>::New();
  notSelectedMapper->SetInputData(notSelected);

  vtkSmartPointer<vtkActor> notSelectedActor = vtkSmartPointer<vtkActor>::New();
  notSelectedActor->SetMapper(notSelectedMapper);

  // There will be one render window
  vtkSmartPointer<vtkRenderWindow> renderWindow =
      vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetSize(900, 300);

  // And one interactor
  vtkSmartPointer<vtkRenderWindowInteractor> interactor =
      vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  // Define viewport ranges
  // (xmin, ymin, xmax, ymax)
  double leftViewport[4] = {0.0, 0.0, 0.33, 1.0};
  double centerViewport[4] = {0.33, 0.0, .66, 1.0};
  double rightViewport[4] = {0.66, 0.0, 1.0, 1.0};

  // Setup the renderers
  vtkSmartPointer<vtkRenderer> leftRenderer =
      vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(leftRenderer);
  leftRenderer->SetViewport(leftViewport);
  leftRenderer->SetBackground(colors->GetColor3d("leftBkg").GetData());

  vtkSmartPointer<vtkRenderer> centerRenderer =
      vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(centerRenderer);
  centerRenderer->SetViewport(centerViewport);
  centerRenderer->SetBackground(colors->GetColor3d("centreBkg").GetData());

  vtkSmartPointer<vtkRenderer> rightRenderer =
      vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(rightRenderer);
  rightRenderer->SetViewport(rightViewport);
  rightRenderer->SetBackground(colors->GetColor3d("rightBkg").GetData());

  leftRenderer->AddActor(inputActor);
  centerRenderer->AddActor(selectedActor);
  rightRenderer->AddActor(notSelectedActor);

  leftRenderer->ResetCamera();
  centerRenderer->ResetCamera();
  rightRenderer->ResetCamera();

  renderWindow->Render();
  interactor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ExtractSelection)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersExtraction
  vtkFiltersGeneral
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping ExtractSelection: ${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(ExtractSelection MACOSX_BUNDLE ExtractSelection.cxx )
  target_link_libraries(ExtractSelection PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ExtractSelection MACOSX_BUNDLE ExtractSelection.cxx )
  target_link_libraries(ExtractSelection PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ExtractSelection
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build ExtractSelection

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

cd ExtractSelection/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:

./ExtractSelection

WINDOWS USERS

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