# OctreeClosestPoint

VTKExamples/Cxx/DataStructures/OctreeClosestPoint

### Code

OctreeClosestPoint.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkIdList.h>
    #include <vtkOctreePointLocator.h>

    int main(int, char *[])
    {
      // Setup point coordinates
      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(x);
      points->InsertNextPoint(y);
      points->InsertNextPoint(z);

      vtkSmartPointer<vtkPolyData> polydata =
        vtkSmartPointer<vtkPolyData>::New();
      polydata->SetPoints(points);

      // Create the tree
      vtkSmartPointer<vtkOctreePointLocator> octree =
        vtkSmartPointer<vtkOctreePointLocator>::New();
      octree->SetDataSet(polydata);
      octree->BuildLocator();

      double testPoint[3] = {2.0, 0.0, 0.0};

      // Find the closest points to TestPoint
      vtkIdType iD = octree->FindClosestPoint(testPoint);
      std::cout << "The closest point is point " << iD << std::endl;

      // Get the coordinates of the closest point
      double closestPoint[3];
      octree->GetDataSet()->GetPoint(iD, closestPoint);
      std::cout << "Coordinates: " << closestPoint[0] << " "
                << closestPoint[1] << " " << closestPoint[2] << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(OctreeClosestPoint)

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

### Download and Build OctreeClosestPoint

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

    cd OctreeClosestPoint/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:

    ./OctreeClosestPoint

WINDOWS USERS

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