# Spring

VTKExamples/Cxx/Modelling/Spring

### Code

Spring.cxx

    #include <vtkRotationalExtrusionFilter.h>

    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkPoints.h>
    #include <vtkCellArray.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataNormals.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkProperty.h>
    #include <vtkNamedColors.h>

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

    // Create the RenderWindow, Renderer and both Actors
    //
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);

      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      interactor->SetRenderWindow(renderWindow);

    // create spring profile (a circle)
    //
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertPoint(0, 1.0, 0.0, 0.0);
      points->InsertPoint(1, 1.0732, 0.0, -0.1768);
      points->InsertPoint(2, 1.25, 0.0, -0.25);
      points->InsertPoint(3, 1.4268, 0.0, -0.1768);
      points->InsertPoint(4, 1.5, 0.0, 0.00);
      points->InsertPoint(5, 1.4268, 0.0, 0.1768);
      points->InsertPoint(6, 1.25, 0.0, 0.25);
      points->InsertPoint(7, 1.0732, 0.0, 0.1768);

      vtkSmartPointer<vtkCellArray> poly =
        vtkSmartPointer<vtkCellArray>::New();
      poly->InsertNextCell(8);//number of points
      poly->InsertCellPoint(0);
      poly->InsertCellPoint(1);
      poly->InsertCellPoint(2);
      poly->InsertCellPoint(3);
      poly->InsertCellPoint(4);
      poly->InsertCellPoint(5);
      poly->InsertCellPoint(6);
      poly->InsertCellPoint(7);

      vtkSmartPointer<vtkPolyData> profile =
        vtkSmartPointer<vtkPolyData>::New();
      profile->SetPoints(points);
      profile->SetPolys(poly);

    // extrude profile to make spring
    //
      vtkSmartPointer<vtkRotationalExtrusionFilter> extrude =
        vtkSmartPointer<vtkRotationalExtrusionFilter>::New();
      extrude->SetInputData(profile);
      extrude->SetResolution(360);
      extrude->SetTranslation(6);
      extrude->SetDeltaRadius(1.0);
      extrude->SetAngle(2160.0);//six revolutions

      vtkSmartPointer<vtkPolyDataNormals> normals =
        vtkSmartPointer<vtkPolyDataNormals>::New();
      normals->SetInputConnection(extrude->GetOutputPort());
      normals->SetFeatureAngle(60);

      vtkSmartPointer<vtkPolyDataMapper> map =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      map->SetInputConnection(normals->GetOutputPort());

      vtkSmartPointer<vtkActor> spring =
        vtkSmartPointer<vtkActor>::New();
      spring->SetMapper(map);
      spring->GetProperty()->SetColor(colors->GetColor3d("PowderBlue").GetData());
      spring->GetProperty()->SetDiffuse(0.7);
      spring->GetProperty()->SetSpecular(0.4);
      spring->GetProperty()->SetSpecularPower(20);
      spring->GetProperty()->BackfaceCullingOn();

    // Add the actors to the renderer, set the background and size
    //
      renderer->AddActor(spring);
      renderer->SetBackground(colors->GetColor3d("Burlywood").GetData());
      renderWindow->SetSize(640, 512);

      renderer->ResetCamera();
      renderer->GetActiveCamera()->Azimuth(90);

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

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(Spring)

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

    add_executable(Spring MACOSX_BUNDLE Spring.cxx )

    target_link_libraries(Spring ${VTK_LIBRARIES})

### Download and Build Spring

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

    cd Spring/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:

    ./Spring

WINDOWS USERS

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