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, src/Testing/Data/v.vtk,, src/Testing/Data/t.vtk and src/Testing/Data/k.vtk.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

ViewportBorders.cxx

#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkCellArray.h>
#include <vtkCoordinate.h>
#include <vtkNamedColors.h>
#include <vtkNew.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>

namespace {
void ViewportBorder(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 e.g. v.vtk t.vtk k.vtk"
              << std::endl;
    return EXIT_FAILURE;
  }

  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(300 * numberOfFiles, 300);
  renderWindow->SetWindowName("ViewportBorders");

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

    vtkNew<vtkPolyDataMapper> mapper;
    mapper->SetInputConnection(reader->GetOutputPort());

    vtkNew<vtkActor> actor;
    actor->SetMapper(mapper);
    actor->GetProperty()->SetColor(colors->GetColor3d("Silver").GetData());

    vtkNew<vtkRenderer> renderer;
    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);
  }

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);
  renderWindow->Render();
  interactor->Initialize();
  interactor->Start();

  return EXIT_SUCCESS;
}
namespace {
// Draw the borders of a renderer's viewport.
void ViewportBorder(vtkRenderer* renderer, double* color, bool last)
{
  // points start at upper right and proceed anti-clockwise
  vtkNew<vtkPoints> points;
  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.
  vtkNew<vtkCellArray> cells;
  cells->Initialize();

  vtkNew<vtkPolyLine> lines;

  // 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 the polydata and display it.
  vtkNew<vtkPolyData> poly;
  poly->Initialize();
  poly->SetPoints(points);
  poly->SetLines(cells);

  // Use normalized viewport coordinates since
  // they are independent of window size.
  vtkNew<vtkCoordinate> coordinate;
  coordinate->SetCoordinateSystemToNormalizedViewport();

  vtkNew<vtkPolyDataMapper2D> mapper;
  mapper->SetInputData(poly);
  mapper->SetTransformCoordinate(coordinate);

  vtkNew<vtkActor2D> actor;
  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);
}
} // namespace

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ViewportBorders)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  IOLegacy
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ViewportBorders: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(ViewportBorders MACOSX_BUNDLE ViewportBorders.cxx )
  target_link_libraries(ViewportBorders PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ViewportBorders
  MODULES ${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

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