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BackgroundImage

vtk-examples/Cxx/Images/BackgroundImage


Description

This example displays an image as the "background" of a scene, and renders a superquadric in front of it.

The example accepts a jpeg file on the command line to use as a background image. If there is no file, it generates a simple background.

Other languages

See (Python)

Question

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

Code

BackgroundImage.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkImageActor.h>
#include <vtkImageCanvasSource2D.h>
#include <vtkImageData.h>
#include <vtkImageReader2.h>
#include <vtkImageReader2Factory.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkSuperquadricSource.h>

#include <array>

int main(int argc, char* argv[])
{
  vtkNew<vtkNamedColors> colors;

  vtkSmartPointer<vtkImageData> imageData;

  // Verify input arguments
  if (argc > 1)
  {
    // Read the image
    vtkNew<vtkImageReader2Factory> readerFactory;
    vtkSmartPointer<vtkImageReader2> imageReader;
    imageReader.TakeReference(readerFactory->CreateImageReader2(argv[1]));
    imageReader->SetFileName(argv[1]);
    imageReader->Update();
    imageData = imageReader->GetOutput();
  }
  else
  {

    std::array<double, 3> drawColor1{0, 0, 0};
    std::array<double, 3> drawColor2{0, 0, 0};
    std::array<double, 3> drawColor3{0, 0, 0};
    auto color1 = colors->GetColor3ub("warm_grey").GetData();
    auto color2 = colors->GetColor3ub("DarkCyan").GetData();
    auto color3 = colors->GetColor3ub("LightCoral").GetData();
    for (auto i = 0; i < 3; ++i)
    {
      drawColor1[i] = color1[i];
      drawColor2[i] = color2[i];
      drawColor3[i] = color3[i];
    }

    vtkNew<vtkImageCanvasSource2D> canvasSource;
    canvasSource->SetExtent(0, 100, 0, 100, 0, 0);
    canvasSource->SetScalarTypeToUnsignedChar();
    canvasSource->SetNumberOfScalarComponents(3);
    canvasSource->SetDrawColor(drawColor1.data());
    canvasSource->FillBox(0, 100, 0, 100);
    canvasSource->SetDrawColor(drawColor2.data());
    canvasSource->FillTriangle(10, 10, 25, 10, 25, 25);
    canvasSource->SetDrawColor(drawColor3.data());
    canvasSource->FillTube(75, 75, 0, 75, 5.0);
    canvasSource->Update();
    imageData = canvasSource->GetOutput();
  }
  // Create an image actor to display the image
  vtkNew<vtkImageActor> imageActor;
  imageActor->SetInputData(imageData);

  // Create a renderer to display the image in the background
  vtkNew<vtkRenderer> backgroundRenderer;

  // Create a superquadric
  vtkNew<vtkSuperquadricSource> superquadricSource;
  superquadricSource->SetPhiRoundness(1.1);
  superquadricSource->SetThetaRoundness(.2);

  // Create a mapper and actor
  vtkNew<vtkPolyDataMapper> superquadricMapper;
  superquadricMapper->SetInputConnection(superquadricSource->GetOutputPort());

  vtkNew<vtkActor> superquadricActor;
  superquadricActor->SetMapper(superquadricMapper);
  superquadricActor->GetProperty()->SetColor(
      colors->GetColor3d("NavajoWhite").GetData());

  vtkNew<vtkRenderer> sceneRenderer;

  vtkNew<vtkRenderWindow> renderWindow;

  // Set up the render window and renderers such that there is
  // a background layer and a foreground layer
  backgroundRenderer->SetLayer(0);
  backgroundRenderer->InteractiveOff();
  sceneRenderer->SetLayer(1);
  renderWindow->SetNumberOfLayers(2);
  renderWindow->AddRenderer(backgroundRenderer);
  renderWindow->AddRenderer(sceneRenderer);
  renderWindow->SetWindowName("BackgroundImage");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add actors to the renderers
  sceneRenderer->AddActor(superquadricActor);
  backgroundRenderer->AddActor(imageActor);

  // Render once to figure out where the background camera will be
  renderWindow->Render();

  // Set up the background camera to fill the renderer with the image
  double origin[3];
  double spacing[3];
  int extent[6];
  imageData->GetOrigin(origin);
  imageData->GetSpacing(spacing);
  imageData->GetExtent(extent);

  vtkCamera* camera = backgroundRenderer->GetActiveCamera();
  camera->ParallelProjectionOn();

  double xc = origin[0] + 0.5 * (extent[0] + extent[1]) * spacing[0];
  double yc = origin[1] + 0.5 * (extent[2] + extent[3]) * spacing[1];
  // double xd = (extent[1] - extent[0] + 1)*spacing[0];
  double yd = (extent[3] - extent[2] + 1) * spacing[1];
  double d = camera->GetDistance();
  camera->SetParallelScale(0.5 * yd);
  camera->SetFocalPoint(xc, yc, 0.0);
  camera->SetPosition(xc, yc, d);

  // Render again to set the correct view
  renderWindow->Render();

  // Interact with the window
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BackgroundImage)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  vtkIOImage
  vtkImagingSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping BackgroundImage: ${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(BackgroundImage MACOSX_BUNDLE BackgroundImage.cxx )
  target_link_libraries(BackgroundImage PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(BackgroundImage MACOSX_BUNDLE BackgroundImage.cxx )
  target_link_libraries(BackgroundImage PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS BackgroundImage
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build BackgroundImage

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

cd BackgroundImage/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:

./BackgroundImage

WINDOWS USERS

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