# PiecewiseFunction

VTKExamples/Cxx/Utilities/PiecewiseFunction

### Code

PiecewiseFunction.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPiecewiseFunction.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkPiecewiseFunction> piecewiseFunction =
          vtkSmartPointer<vtkPiecewiseFunction>::New();
      piecewiseFunction->AddPoint(0.0, 0.0);
      piecewiseFunction->AddPoint(1.0, 2.0);

      double test = piecewiseFunction->GetValue(0.25);

      std::cout << "test: " << test << " (should be 0.5)" << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(PiecewiseFunction)

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

### Download and Build PiecewiseFunction

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

    cd PiecewiseFunction/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:

    ./PiecewiseFunction

WINDOWS USERS

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