# SampleFunction

VTKExamples/Cxx/ImplicitFunctions/SampleFunction

Other Languages

See (Python), (CSharp)

### Code

SampleFunction.cxx

    #include <vtkSmartPointer.h>
    #include <vtkSampleFunction.h>
    #include <vtkContourFilter.h>

    #include <vtkOutlineFilter.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkImageData.h>

    #include <vtkSuperquadric.h>
    #include <vtkNamedColors.h>

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

      vtkSmartPointer<vtkSuperquadric> implicitFunction =
        vtkSmartPointer<vtkSuperquadric>::New();
      implicitFunction->SetPhiRoundness(2.5);
      implicitFunction->SetThetaRoundness(.5);

      // Sample the function
      vtkSmartPointer<vtkSampleFunction> sample =
        vtkSmartPointer<vtkSampleFunction>::New();
      sample->SetSampleDimensions(50,50,50);
      sample->SetImplicitFunction(implicitFunction);
      double value = 2.0;
      double xmin = -value, xmax = value, ymin = -value, ymax = value, zmin = -value, zmax = value;
      sample->SetModelBounds(xmin, xmax, ymin, ymax, zmin, zmax);

      // Create the 0 isosurface
      vtkSmartPointer<vtkContourFilter> contours =
        vtkSmartPointer<vtkContourFilter>::New();
      contours->SetInputConnection(sample->GetOutputPort());
      contours->GenerateValues(1, 2.0, 2.0);

      // Map the contours to graphical primitives
      vtkSmartPointer<vtkPolyDataMapper> contourMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      contourMapper->SetInputConnection(contours->GetOutputPort());
      contourMapper->SetScalarRange(0.0, 1.2);

      // Create an actor for the contours
      vtkSmartPointer<vtkActor> contourActor =
        vtkSmartPointer<vtkActor>::New();
      contourActor->SetMapper(contourMapper);

      // -- create a box around the function to indicate the sampling volume --

      // Create outline
      vtkSmartPointer<vtkOutlineFilter> outline =
        vtkSmartPointer<vtkOutlineFilter>::New();
      outline->SetInputConnection(sample->GetOutputPort());

      // Map it to graphics primitives
      vtkSmartPointer<vtkPolyDataMapper> outlineMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      outlineMapper->SetInputConnection(outline->GetOutputPort());

      // Create an actor for it
      vtkSmartPointer<vtkActor> outlineActor =
        vtkSmartPointer<vtkActor>::New();
      outlineActor->SetMapper(outlineMapper);
      outlineActor->GetProperty()->SetColor(0,0,0);

      // Visualize
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

      renderer->AddActor(contourActor);
      renderer->AddActor(outlineActor);
      renderer->SetBackground(colors->GetColor3d("Tan").GetData());

      renderWindow->Render();
      interactor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(SampleFunction)

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

### Download and Build SampleFunction

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

    cd SampleFunction/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:

    ./SampleFunction

WINDOWS USERS

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