# DiscretizableColorTransferFunction

VTKExamples/Cxx/Utilities/DiscretizableColorTransferFunction

### Code

DiscretizableColorTransferFunction.cxx

    #include <vtkSmartPointer.h>
    #include <vtkDiscretizableColorTransferFunction.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkDiscretizableColorTransferFunction> discretizableColorTransferFunction =
        vtkSmartPointer<vtkDiscretizableColorTransferFunction>::New();

      discretizableColorTransferFunction->DiscretizeOn();
      discretizableColorTransferFunction->SetNumberOfValues(2);

      discretizableColorTransferFunction->AddRGBPoint(0.0, 1, 0, 0);
      discretizableColorTransferFunction->AddRGBPoint(10.0, 0, 1, 0);
      discretizableColorTransferFunction->Build();

      double color[3];
      discretizableColorTransferFunction->GetColor(1.0, color);
      std::cout << color[0] << " " << color[1] << " " << color[2] << std::endl;

      discretizableColorTransferFunction->GetColor(5.0, color);
      std::cout << color[0] << " " << color[1] << " " << color[2] << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(DiscretizableColorTransferFunction)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping DiscretizableColorTransferFunction: ${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(DiscretizableColorTransferFunction MACOSX_BUNDLE DiscretizableColorTransferFunction.cxx )
      target_link_libraries(DiscretizableColorTransferFunction PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(DiscretizableColorTransferFunction MACOSX_BUNDLE DiscretizableColorTransferFunction.cxx )
      target_link_libraries(DiscretizableColorTransferFunction PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS DiscretizableColorTransferFunction
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build DiscretizableColorTransferFunction

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

    cd DiscretizableColorTransferFunction/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:

    ./DiscretizableColorTransferFunction

WINDOWS USERS

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