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ImageOrder

vtk-examples/Cxx/Images/ImageOrder


Question

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Code

ImageOrder.cxx

#include <vtkImageActor.h>
#include <vtkImageData.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <array>

#define DISPLAY_FIRST_IMAGE
// Comment this out to display the first image.
#undef DISPLAY_FIRST_IMAGE

namespace {
void CreateColorImage(vtkImageData* image, std::string const& colorName);
}

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

  // Image 1
  vtkNew<vtkImageData> firstImage;
  CreateColorImage(firstImage, "DarkOliveGreen");

  vtkNew<vtkImageActor> firstImageActor;
  firstImageActor->SetInputData(firstImage);

  // Image 2
  vtkNew<vtkImageData> secondImage;
  CreateColorImage(secondImage, "DarkSalmon");

  vtkNew<vtkImageActor> secondImageActor;
  secondImageActor->SetInputData(secondImage);

  // Visualize
  vtkNew<vtkRenderer> renderer;

#ifdef DISPLAY_FIRST_IMAGE
  // The first image is displayed
  renderer->AddActor(secondImageActor);
  renderer->AddActor(firstImageActor);
#else
  // The second image is displayed
  renderer->AddActor(firstImageActor);
  renderer->AddActor(secondImageActor);
#endif

  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
  renderer->ResetCamera();

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("ImageOrder");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  vtkNew<vtkInteractorStyleImage> style;

  renderWindowInteractor->SetInteractorStyle(style);

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

  return EXIT_SUCCESS;
}

namespace {
void CreateColorImage(vtkImageData* image, std::string const& colorName)
{
  vtkNew<vtkNamedColors> colors;

  std::array<unsigned char, 3> drawColor{0, 0, 0};
  auto color = colors->GetColor3ub(colorName).GetData();
  for (auto i = 0; i < 3; ++i)
  {
    drawColor[i] = color[i];
  }

  unsigned int dim = 10;

  image->SetDimensions(dim, dim, 1);
  image->AllocateScalars(VTK_UNSIGNED_CHAR, 3);

  for (unsigned int x = 0; x < dim; x++)
  {
    for (unsigned int y = 0; y < dim; y++)
    {
      auto pixel =
          static_cast<unsigned char*>(image->GetScalarPointer(x, y, 0));
      for (auto i = 0; i < 3; ++i)
      {
        pixel[i] = drawColor[i];
      }
    }
  }

  image->Modified();
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ImageOrder)

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

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

Download and Build ImageOrder

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

cd ImageOrder/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:

./ImageOrder

WINDOWS USERS

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