# MergePoints

VTKExamples/Cxx/PolyData/MergePoints

### Description

Add new points if they are unique. You must add the original points first. After that, the locator will only add unique points.

### Code

MergePoints.cxx

    #include <vtkSmartPointer.h>

    #include <vtkMath.h>
    #include <vtkMergePoints.h>
    #include <vtkPointSource.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>

    int main(int, char *[])
    {
      // Create a set of points
      vtkSmartPointer<vtkPointSource> pointsSource =
        vtkSmartPointer<vtkPointSource>::New();
      pointsSource->SetNumberOfPoints(100);
      pointsSource->Update();

      vtkPolyData* points = pointsSource->GetOutput();

      // Get a point point in the set
      double inSet[3];
      points->GetPoint(25, inSet);

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

      vtkIdType id;

      // Insert all of the points
      vtkSmartPointer<vtkMergePoints> mergePoints =
        vtkSmartPointer<vtkMergePoints>::New();
      mergePoints->SetDataSet(points);
      mergePoints->SetDivisions(10,10,10);
      mergePoints->InitPointInsertion(points->GetPoints(), points->GetBounds());

      for (vtkIdType i = 0; i < points->GetNumberOfPoints(); i++)
      {
        mergePoints->InsertUniquePoint(points->GetPoint(i), id);
      }

      // Insert a few of the original points
      std::cout << "Insert some of the original points" << std::endl;
      int inserted;
      for (vtkIdType i = 0; i < points->GetNumberOfPoints(); i+=10)
      {
        points->GetPoint(i, inSet);
        inserted = mergePoints->InsertUniquePoint(inSet, id);
        std::cout << "\tPoint: "
                  << inSet[0] << ", "
                  << inSet[1] << ", "
                  << inSet[2] << " ";

        std::cout << "Inserted? " << ((inserted == 0) ? "No, " : "Yes, ");
        std::cout << "Id:: " << id << std::endl;
      }

      // These points are probably outside the original set of points
      std::cout << "Insert some new points" << std::endl;
      double outsideSet[3];
      for (unsigned int i = 0; i < 10; i++)
      {
        outsideSet[0] = vtkMath::Random(
          -pointsSource->GetRadius(),
          pointsSource->GetRadius());
        outsideSet[1] = vtkMath::Random(
          -pointsSource->GetRadius(),
          pointsSource->GetRadius());
        outsideSet[2] = vtkMath::Random(
          -pointsSource->GetRadius(),
          pointsSource->GetRadius());

        inserted = mergePoints->InsertUniquePoint(outsideSet, id);
        std::cout << "\tPoint: "
                  << outsideSet[0] << ", "
                  << outsideSet[1] << ", "
                  << outsideSet[2] << " ";

        std::cout << "Inserted? " << ((inserted == 0) ? "No, " : "Yes, ");
        std::cout << "Id:: " << id << std::endl;
      }

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(MergePoints)

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

### Download and Build MergePoints

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

    cd MergePoints/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:

    ./MergePoints

WINDOWS USERS

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