BuildLocatorFromKClosestPoints

#include <vtkSmartPointer.h>
#include <vtkPoints.h>
#include <vtkPointSource.h>
#include <vtkIdList.h>
#include <vtkKdTree.h>

int main(int, char *[])
{
  // Create some points
  double origin[3] = {0.0, 0.0, 0.0};
  double x[3] = {1.0, 0.0, 0.0};
  double y[3] = {0.0, 1.0, 0.0};
  double z[3] = {0.0, 0.0, 1.0};

  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(origin);
  points->InsertNextPoint(x);
  points->InsertNextPoint(y);
  points->InsertNextPoint(z);

  // Create the tree
  vtkSmartPointer<vtkKdTree> pointTree =
    vtkSmartPointer<vtkKdTree>::New();
  pointTree->BuildLocatorFromPoints(points);

  // Find the 2 closest points to (0.5,0,0)
  vtkIdType k = 2;
  double testPoint[3] = {0.5, 0.0, 0.0};
  vtkSmartPointer<vtkIdList> result =
    vtkSmartPointer<vtkIdList>::New();

  pointTree->FindClosestNPoints(k, testPoint, result);

  for(vtkIdType i = 0; i < k; i++)
  {
    vtkIdType point_ind = result->GetId(i);
    double p[3];
    points->GetPoint(point_ind, p);
    std::cout << "Closest point "
              << i << ": Point " << point_ind << ": ("
              << p[0] << ", " << p[1] << ", " << p[2] << ")" << std::endl;
  }

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BuildLocatorFromKClosestPoints)

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

cd BuildLocatorFromKClosestPoints/build 

cmake ..

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

make

./BuildLocatorFromKClosestPoints