# KdTree

VTKExamples/Cxx/DataStructures/KdTree

### Description

This example demonstrates how to use vtkKdTree to build a tree from a vtkPoints object. Note that since AddDataSet or SetDataSet were not called, you cannot use GetDataSet.

### Code

KdTree.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkIdList.h>
    #include <vtkKdTree.h>
    #include <vtkVertexGlyphFilter.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);

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

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

      //Find the closest points to TestPoint
      double closestPointDist;
      vtkIdType id = kDTree->FindClosestPoint(testPoint, closestPointDist); //vtkKdTree::FindClosestPoint: must build locator first
      std::cout << "The closest point is point " << id << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(KdTree)

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

    add_executable(KdTree MACOSX_BUNDLE KdTree.cxx)

    target_link_libraries(KdTree ${VTK_LIBRARIES})

### Download and Build KdTree

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

    cd KdTree/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:

    ./KdTree

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