# OBBTreeIntersectWithLine

VTKExamples/Cxx/DataStructures/OBBTreeIntersectWithLine

### Description

vtkOBBTree returns ALL intersections with a line and the dataset. If you want the closest intersection, you must manually find it. In this example, we create a sphere and intersect a single line with it.

### Code

OBBTreeIntersectWithLine.cxx

    #include <vtkSmartPointer.h>
    #include <vtkSphereSource.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkPointData.h>
    #include <vtkLine.h>
    #include <vtkOBBTree.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->Update();

      // Create the locator
      vtkSmartPointer<vtkOBBTree> tree =
        vtkSmartPointer<vtkOBBTree>::New();
      tree->SetDataSet(sphereSource->GetOutput());
      tree->BuildLocator();

      // Intersect the locator with the line
      double lineP0[3] = {0.0, 0.0, 0.0};
      double lineP1[3] = {0.0, 0.0, 2.0};
      vtkSmartPointer<vtkPoints> intersectPoints =
        vtkSmartPointer<vtkPoints>::New();

      tree->IntersectWithLine(lineP0, lineP1, intersectPoints, NULL);

      std::cout << "NumPoints: " << intersectPoints->GetNumberOfPoints()
                << std::endl;

      // Display list of intersections
      double intersection[3];
      for(int i = 0; i < intersectPoints->GetNumberOfPoints(); i++ )
      {
        intersectPoints->GetPoint(i, intersection);
        std::cout << "Intersection " << i << ": "
                  << intersection[0] << ", "
                  << intersection[1] << ", "
                  << intersection[2] << std::endl;
      }

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(OBBTreeIntersectWithLine)

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

    add_executable(OBBTreeIntersectWithLine MACOSX_BUNDLE OBBTreeIntersectWithLine.cxx )

    target_link_libraries(OBBTreeIntersectWithLine ${VTK_LIBRARIES})

### Download and Build OBBTreeIntersectWithLine

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

    cd OBBTreeIntersectWithLine/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:

    ./OBBTreeIntersectWithLine

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.