# TubesWithVaryingRadiusAndColors

VTKExamples/Cxx/VisualizationAlgorithms/TubesWithVaryingRadiusAndColors

### Description

This example shows how to vary the radius of a tube with one scalar and color the tube with another.

- Contributed by Marcus Thamson

Note

This original source code for this example is here.

### Code

TubesWithVaryingRadiusAndColors.cxx

    #include <math.h>

    #include <vtkVersion.h>
    #include <vtkPolyData.h>
    #include <vtkPoints.h>
    #include <vtkCellArray.h>
    #include <vtkDoubleArray.h>
    #include <vtkPolyData.h>
    #include <vtkPointData.h>

    #include <vtkCell.h>
    #include <vtkCellData.h>
    #include <vtkDataSet.h>
    #include <vtkDataSetAttributes.h>
    #include <vtkProperty.h>
    #include <vtkSmartPointer.h>
    #include <vtkTubeFilter.h>

    #include <vtkDataSetMapper.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkCamera.h>
    #include <vtkInteractorStyleTrackballCamera.h>

    #include <vtkMath.h>

    int main (int, char *[])
    {
      // Spiral tube
      double vX, vY, vZ;
      unsigned int nV = 256;      // No. of vertices
      unsigned int nCyc = 5;      // No. of spiral cycles
      double rT1 = 0.1, rT2 = 0.5;// Start/end tube radii
      double rS = 2;              // Spiral radius
      double h = 10;              // Height
      unsigned int nTv = 8;       // No. of surface elements for each tube vertex

      unsigned int i;

      // Create points and cells for the spiral
      vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
      for(i = 0; i < nV; i++)
      {
        // Spiral coordinates
        vX = rS * cos(2 * vtkMath::Pi() * nCyc * i / (nV - 1));
        vY = rS * sin(2 * vtkMath::Pi() * nCyc * i / (nV - 1));
        vZ = h * i / nV;
        points->InsertPoint(i, vX, vY, vZ);
      }

      vtkSmartPointer<vtkCellArray> lines =
        vtkSmartPointer<vtkCellArray>::New();
      lines->InsertNextCell(nV);
      for (i = 0; i < nV; i++)
      {
        lines->InsertCellPoint(i);
      }

      vtkSmartPointer<vtkPolyData> polyData =
        vtkSmartPointer<vtkPolyData>::New();
      polyData->SetPoints(points);
      polyData->SetLines(lines);

      // Varying tube radius using sine-function
      vtkSmartPointer<vtkDoubleArray> tubeRadius =
        vtkSmartPointer<vtkDoubleArray>::New();
      tubeRadius->SetName("TubeRadius");
      tubeRadius->SetNumberOfTuples(nV);
      for (i=0 ;i<nV ; i++)
      {
        tubeRadius->SetTuple1(i,
                              rT1 + (rT2 - rT1) * sin(vtkMath::Pi() * i / (nV - 1)));
      }
      polyData->GetPointData()->AddArray(tubeRadius);
      polyData->GetPointData()->SetActiveScalars("TubeRadius");

      // RBG array (could add Alpha channel too I guess...)
      // Varying from blue to red
      vtkSmartPointer<vtkUnsignedCharArray> colors =
        vtkSmartPointer<vtkUnsignedCharArray>::New();
      colors->SetName("Colors");
      colors->SetNumberOfComponents(3);
      colors->SetNumberOfTuples(nV);
      for (i = 0; i < nV ;i++)
      {
        colors->InsertTuple3(i,
                           int(255 * i/ (nV - 1)),
                           0,
                           int(255 * (nV - 1 - i)/(nV - 1)) );
      }
      polyData->GetPointData()->AddArray(colors);

      vtkSmartPointer<vtkTubeFilter> tube
        = vtkSmartPointer<vtkTubeFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
      tube->SetInput(polyData);
    #else
      tube->SetInputData(polyData);
    #endif
      tube->SetNumberOfSides(nTv);
      tube->SetVaryRadiusToVaryRadiusByAbsoluteScalar();

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(tube->GetOutputPort());
      mapper->ScalarVisibilityOn();
      mapper->SetScalarModeToUsePointFieldData();
      mapper->SelectColorArray("Colors");

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(actor);
      renderer->SetBackground(.2, .3, .4);

      // Make an oblique view
      renderer->GetActiveCamera()->Azimuth(30);
      renderer->GetActiveCamera()->Elevation(30);
      renderer->ResetCamera();

      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      vtkSmartPointer<vtkRenderWindowInteractor>
        iren = vtkSmartPointer<vtkRenderWindowInteractor>::New();

      iren->SetRenderWindow(renWin);
      renWin->AddRenderer(renderer);
      renWin->SetSize(500, 500);
      renWin->Render();

      vtkSmartPointer<vtkInteractorStyleTrackballCamera> style =
        vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();
      iren->SetInteractorStyle(style);

      iren->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(TubesWithVaryingRadiusAndColors)

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

    add_executable(TubesWithVaryingRadiusAndColors MACOSX_BUNDLE TubesWithVaryingRadiusAndColors.cxx )

    target_link_libraries(TubesWithVaryingRadiusAndColors ${VTK_LIBRARIES})

### Download and Build TubesWithVaryingRadiusAndColors

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

    cd TubesWithVaryingRadiusAndColors/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:

    ./TubesWithVaryingRadiusAndColors

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