# PolyLine

VTKExamples/Cxx/GeometricObjects/PolyLine

### Description

The polyline is a composite one-dimensional cell consisting of one or more connected lines. The polyline is defined by an ordered list of n+1 points, where n is the number of lines in the polyline. Each pair of points (i, i+1) defines a line.

Other Languages

See (Python), (CSharp)

### Code

PolyLine.cxx

    #include <vtkActor.h>
    #include <vtkCellArray.h>
    #include <vtkCellData.h>
    #include <vtkDoubleArray.h>
    #include <vtkNamedColors.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkPolyLine.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkSmartPointer.h>

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

      // Create five points.
      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);

      vtkSmartPointer<vtkPolyLine> polyLine =
        vtkSmartPointer<vtkPolyLine>::New();
      polyLine->GetPointIds()->SetNumberOfIds(5);
      for(unsigned int i = 0; i < 5; i++)
      {
        polyLine->GetPointIds()->SetId(i,i);
      }

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

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

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

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

      // Setup actor and mapper
      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputData(polyData);

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetColor(colors->GetColor3d("Tomato").GetData());

      // Setup render window, renderer, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetWindowName("PolyLine");
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);
      renderer->AddActor(actor);
      renderer->SetBackground(colors->GetColor3d("DarkOliveGreen").GetData());

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(PolyLine)

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

### Download and Build PolyLine

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

    cd PolyLine/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:

    ./PolyLine

WINDOWS USERS

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