# KdTreePointLocatorClosestPoint

VTKExamples/Cxx/DataStructures/KdTreePointLocatorClosestPoint

### Description

This example creates a set of three points, builds a KDTree from them, then demonstrates how to find the closest point to a query point.

### Code

KdTreePointLocatorClosestPoint.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkIdList.h>
    #include <vtkKdTreePointLocator.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<vtkKdTreePointLocator> kDTree =
        vtkSmartPointer<vtkKdTreePointLocator>::New();
      kDTree->SetDataSet(polydata);
      kDTree->BuildLocator();

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

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

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(KdTreePointLocatorClosestPoint)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(KdTreePointLocatorClosestPoint MACOSX_BUNDLE KdTreePointLocatorClosestPoint.cxx )

    target_link_libraries(KdTreePointLocatorClosestPoint ${VTK_LIBRARIES})

### Download and Build KdTreePointLocatorClosestPoint

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

    cd KdTreePointLocatorClosestPoint/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:

    ./KdTreePointLocatorClosestPoint

WINDOWS USERS

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