# ResamplePolyLine

VTKExamples/Cxx/PolyData/ResamplePolyLine

### Description

This example resamples a polyline with a vtkCardinalSpline. The resampled line will have 10 times the number of points contained in the original polyline. If no XML file is provided, a random polyline is generated.

### Code

ResamplePolyLine.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>

    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkActor.h>
    #include <vtkPolyDataMapper.h>

    #include <vtkXMLPolyDataReader.h>
    #include <vtkPoints.h>
    #include <vtkMath.h>
    #include <vtkSplineFilter.h>
    #include <vtkSphereSource.h>
    #include <vtkGlyph3D.h>
    #include <vtkProperty.h>
    #include <vtkCellArray.h>
    #include <vtkCardinalSpline.h>

    int main (int argc, char *argv[])
    {
      vtkSmartPointer<vtkPolyData> polyData =
        vtkSmartPointer<vtkPolyData>::New();
      if (argc > 1)
      {
        vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName ( argv[1] );
        reader->Update();
        polyData = reader->GetOutput();
      }
      else
      {
        vtkMath::RandomSeed(8775070);
        unsigned int numberOfPoints = 10;
        vtkSmartPointer<vtkPoints> points =
          vtkSmartPointer<vtkPoints>::New();
        for (unsigned int i = 0; i < numberOfPoints; ++i)
        {
          double x = vtkMath::Random(-1, 1);
          double y = vtkMath::Random(-1, 1);
          double z = vtkMath::Random(-1, 1);
          points->InsertNextPoint(x, y, z);
        }
        vtkSmartPointer<vtkCellArray> lines =
          vtkSmartPointer<vtkCellArray>::New();
        lines->InsertNextCell(numberOfPoints);
        for (unsigned int i = 0; i < numberOfPoints; ++i)
        {
          lines->InsertCellPoint(i);
        }
        polyData->SetPoints(points);
        polyData->SetLines(lines);
      }

      vtkSmartPointer<vtkCardinalSpline> spline =
        vtkSmartPointer<vtkCardinalSpline>::New();
      spline->SetLeftConstraint(2);
      spline->SetLeftValue(0.0);
      spline->SetRightConstraint(2);
      spline->SetRightValue(0.0);

      vtkSmartPointer<vtkSplineFilter> splineFilter =
        vtkSmartPointer<vtkSplineFilter>::New();

    #if VTK_MAJOR_VERSION <= 5
      splineFilter->SetInput(polyData);
    #else
      splineFilter->SetInputData(polyData);
    #endif
      splineFilter->SetNumberOfSubdivisions(polyData->GetNumberOfPoints() * 10);
      splineFilter->SetSpline(spline);

      vtkSmartPointer<vtkPolyDataMapper> splineMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      splineMapper->SetInputConnection(splineFilter->GetOutputPort());

      vtkSmartPointer<vtkActor> splineActor =
        vtkSmartPointer<vtkActor>::New();
      splineActor->SetMapper(splineMapper);

      vtkSmartPointer<vtkSphereSource> originalNodes =
        vtkSmartPointer<vtkSphereSource>::New();
      originalNodes->SetRadius(.04);
      originalNodes->SetPhiResolution(10);
      originalNodes->SetThetaResolution(10);

      vtkSmartPointer<vtkGlyph3D> glyphOriginal =
        vtkSmartPointer<vtkGlyph3D>::New();
    #if VTK_MAJOR_VERSION <= 5
      glyphOriginal->SetInput(polyData);
    #else
      glyphOriginal->SetInputData(polyData);
    #endif
      glyphOriginal->SetSourceConnection(originalNodes->GetOutputPort());

      vtkSmartPointer<vtkSphereSource> newNodes =
        vtkSmartPointer<vtkSphereSource>::New();
      newNodes->SetRadius(.02);
      newNodes->SetPhiResolution(10);
      newNodes->SetThetaResolution(10);

      vtkSmartPointer<vtkGlyph3D> glyphNew =
        vtkSmartPointer<vtkGlyph3D>::New();
      glyphNew->SetInputConnection(splineFilter->GetOutputPort());
      glyphNew->SetSourceConnection(newNodes->GetOutputPort());

      vtkSmartPointer<vtkPolyDataMapper> originalMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      originalMapper->SetInputConnection(glyphOriginal->GetOutputPort());

      vtkSmartPointer<vtkActor> originalActor =
        vtkSmartPointer<vtkActor>::New();
      originalActor->SetMapper(originalMapper);
      originalActor->GetProperty()->SetColor(0.8900, 0.8100, 0.3400);
      originalActor->GetProperty()->SetOpacity(.6);

      vtkSmartPointer<vtkPolyDataMapper> newMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      newMapper->SetInputConnection(glyphNew->GetOutputPort());

      vtkSmartPointer<vtkActor> newActor =
        vtkSmartPointer<vtkActor>::New();
      newActor->SetMapper(newMapper);
      newActor->GetProperty()->SetColor(1.0000, 0.3882, 0.2784);

      // A renderer and render window
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      renderer->SetBackground(.1, .2, .4);

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

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

      // Add the actors to the scene
      renderer->AddActor(originalActor);
      renderer->AddActor(newActor);
      renderer->AddActor(splineActor);

      renderWindow->Render();

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ResamplePolyLine)

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

    add_executable(ResamplePolyLine MACOSX_BUNDLE ResamplePolyLine.cxx)

    target_link_libraries(ResamplePolyLine ${VTK_LIBRARIES})

### Download and Build ResamplePolyLine

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

    cd ResamplePolyLine/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:

    ./ResamplePolyLine

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.