# ModifiedBSPTreeIntersectWithLine

VTKExamples/Cxx/DataStructures/ModifiedBSPTreeIntersectWithLine

### Code

ModifiedBSPTreeIntersectWithLine.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPolyData.h>
    #include <vtkModifiedBSPTree.h>
    #include <vtkSphereSource.h>

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

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

      // Inputs
      double p1[3] = {-2,0,0};
      double p2[3] = {2,0,0};
      double tolerance = .001;

      // Outputs
      double t; // Parametric coordinate of intersection (0 (corresponding to p1) to 1 (corresponding to p2))
      double x[3]; // The coordinate of the intersection
      double pcoords[3];
      int subId;

      // Note: for a typical use case (ray-triangle intersection), pcoords and subId will not be used
      vtkIdType iD = bspTree->IntersectWithLine(p1, p2, tolerance, t, x, pcoords, subId);

      std::cout << "iD: " << iD << std::endl;
      std::cout << "t: " << t << std::endl;
      std::cout << "x: " << x[0] << " " << x[1] << " " << x[2] << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(ModifiedBSPTreeIntersectWithLine)

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

### Download and Build ModifiedBSPTreeIntersectWithLine

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

    cd ModifiedBSPTreeIntersectWithLine/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:

    ./ModifiedBSPTreeIntersectWithLine

WINDOWS USERS

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