# ViewportBorders

VTKExamples/Cxx/Utilities/ViewportBorders

### Description

Sometimes multiple vtkRenderer viewports can be difficult to differentiate. This example draws a border around each viewport. The example creates a vtkPolyLine that outlines the viewport. The coordinates for the vtkPoints are specified in normalized viewport coordinates. The coordinate selection is made with a vtkCoordinate. The vtkPolyDataMapper2D and vtkActor2D render the border.

To run the example, provide 1-N vtkPolyDataReader files.

This examples uses the data v.vtk, t.vtk and k.vtk.

### Code

ViewportBorders.cxx

    #include <vtkSmartPointer.h>

    #include <vtkActor.h>
    #include <vtkActor2D.h>
    #include <vtkCellArray.h>
    #include <vtkCoordinate.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkPolyDataMapper2D.h>
    #include <vtkPolyDataReader.h>
    #include <vtkPolyLine.h>
    #include <vtkProperty.h>
    #include <vtkProperty2D.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkNamedColors.h>

    namespace
    {
    void ViewportBorder(vtkSmartPointer<vtkRenderer> &renderer,
                        double *color,
                        bool last = false);
    }

    int main (int argc, char *argv[])
    {
      //
      int numberOfFiles = argc - 1;
      if (numberOfFiles == 0)
      {
        std::cout << "Usage" << argv[0]
                  << " file1 file2 file3 ... fileN" << std::endl;
        return EXIT_FAILURE;
      }
      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(300 * numberOfFiles, 300);

      double size = 1.0 / numberOfFiles;
      for (unsigned int i = 0; static_cast<int>(i) < numberOfFiles; ++i)
      {
        vtkSmartPointer<vtkPolyDataReader> reader =
          vtkSmartPointer<vtkPolyDataReader>::New();
        reader->SetFileName(argv[i + 1]);

        vtkSmartPointer<vtkPolyDataMapper> mapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
        mapper->SetInputConnection(reader->GetOutputPort());

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

        vtkSmartPointer<vtkRenderer> renderer =
          vtkSmartPointer<vtkRenderer>::New();
        renderer->AddActor(actor);
        renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

        double viewport[4];
        viewport[0] = size * i;
        viewport[1] = 0.0;
        viewport[2] = size * (i + 1);
        viewport[3] = 1.0;
        renderer->SetViewport(viewport);
        ViewportBorder(renderer,
                       colors->GetColor3d("Gold").GetData(),
                       static_cast<int>(i) == numberOfFiles - 1);
        renderWindow->AddRenderer(renderer);
      }

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

      return EXIT_SUCCESS;
    }
    namespace
    {
    // draw the borders of a renderer's viewport
    void ViewportBorder(vtkSmartPointer<vtkRenderer> &renderer,
                        double *color,
                        bool last)
    {
      // points start at upper right and proceed anti-clockwise
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->SetNumberOfPoints(4);
      points->InsertPoint(0, 1, 1, 0);
      points->InsertPoint(1, 0, 1, 0);
      points->InsertPoint(2, 0, 0, 0);
      points->InsertPoint(3, 1, 0, 0);

      // create cells, and lines
      vtkSmartPointer<vtkCellArray> cells =
        vtkSmartPointer<vtkCellArray>::New();
      cells->Initialize();

      vtkSmartPointer<vtkPolyLine> lines =
        vtkSmartPointer<vtkPolyLine>::New();

      // only draw last line if this is the last viewport
      // this prevents double vertical lines at right border
      // if different colors are used for each border, then do
      // not specify last
      if (last)
      {
        lines->GetPointIds()->SetNumberOfIds(5);
      }
      else
      {
      lines->GetPointIds()->SetNumberOfIds(4);
      }
      for(unsigned int i = 0; i < 4; ++i)
      {
        lines->GetPointIds()->SetId(i,i);
      }
      if (last)
      {
        lines->GetPointIds()->SetId(4, 0);
      }
      cells->InsertNextCell(lines);

      // now make tge polydata and display it
      vtkSmartPointer<vtkPolyData> poly =
        vtkSmartPointer<vtkPolyData>::New();
      poly->Initialize();
      poly->SetPoints(points);
      poly->SetLines(cells);

      // use normalized viewport coordinates since
      // they are independent of window size
      vtkSmartPointer<vtkCoordinate> coordinate =
        vtkSmartPointer<vtkCoordinate>::New();
      coordinate->SetCoordinateSystemToNormalizedViewport();

      vtkSmartPointer<vtkPolyDataMapper2D> mapper =
        vtkSmartPointer<vtkPolyDataMapper2D>::New();
      mapper->SetInputData(poly);
      mapper->SetTransformCoordinate(coordinate);

      vtkSmartPointer<vtkActor2D> actor =
        vtkSmartPointer<vtkActor2D>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetColor(color);
      // line width should be at least 2 to be visible at extremes

      actor->GetProperty()->SetLineWidth(4.0); // Line Width

      renderer->AddViewProp(actor);
    }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ViewportBorders)

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

    add_executable(ViewportBorders MACOSX_BUNDLE ViewportBorders.cxx )

    target_link_libraries(ViewportBorders ${VTK_LIBRARIES})

### Download and Build ViewportBorders

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

    cd ViewportBorders/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:

    ./ViewportBorders

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.