# IterateOverLines

VTKExamples/Cxx/PolyData/IterateOverLines

### Description

(If anyone can explain why the commented section doesn't work the same as the uncommented section, or fix it, that would be great.)

### Code

IterateOverLines.cxx

    #include <vtkSmartPointer.h>
    #include <vtkLine.h>
    #include <vtkCellArray.h>
    #include <vtkPolyData.h>
    #include <vtkPoints.h>

    int main(int, char *[])
    {
      double origin[3] = {0.0, 0.0, 0.0};
      double p0[3] = {1.0, 0.0, 0.0};
      double p1[3] = {0.0, 1.0, 0.0};
      double p2[3] = {0.0, 1.0, 2.0};
      double p3[3] = {1.0, 2.0, 3.0};

      // Create a vtkPoints object and store the points in it
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(origin);
      points->InsertNextPoint(p0);
      points->InsertNextPoint(p1);
      points->InsertNextPoint(p2);
      points->InsertNextPoint(p3);

      // Create a cell array to store the lines in and add the lines to it
      vtkSmartPointer<vtkCellArray> lines =
        vtkSmartPointer<vtkCellArray>::New();

      //Create four lines
      for(unsigned int i = 0; i < 4; i++)
      {
        vtkSmartPointer<vtkLine> line =
          vtkSmartPointer<vtkLine>::New();
        line->GetPointIds()->SetId(0,i);
        line->GetPointIds()->SetId(1,i+1);
        lines->InsertNextCell(line);
      }

      // Create a polydata to store everything in
      vtkSmartPointer<vtkPolyData> linesPolyData =
        vtkSmartPointer<vtkPolyData>::New();

      // Add the points to the dataset
      linesPolyData->SetPoints(points);

      // Add the lines to the dataset
      linesPolyData->SetLines(lines);

      std::cout << "There are " << linesPolyData->GetNumberOfLines() << " lines." << std::endl;

      linesPolyData->GetLines()->InitTraversal();
      vtkSmartPointer<vtkIdList> idList = vtkSmartPointer<vtkIdList>::New();
      while(linesPolyData->GetLines()->GetNextCell(idList))
      {
        std::cout << "Line has " << idList->GetNumberOfIds() << " points." << std::endl;

        for(vtkIdType pointId = 0; pointId < idList->GetNumberOfIds(); pointId++)
        {
          std::cout << idList->GetId(pointId) << " ";
        }
        std::cout << std::endl;
      }
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(IterateOverLines)

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

    add_executable(IterateOverLines MACOSX_BUNDLE IterateOverLines.cxx)

    target_link_libraries(IterateOverLines ${VTK_LIBRARIES})

### Download and Build IterateOverLines

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

    cd IterateOverLines/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:

    ./IterateOverLines

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.