VectorField

#include <vtkArrowSource.h>
#include <vtkCellArray.h>
#include <vtkGlyph2D.h>
#include <vtkImageData.h>
#include <vtkImageSlice.h>
#include <vtkImageSliceMapper.h>
#include <vtkInteractorStyleImage.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkXMLPolyDataWriter.h>

int main(int, char*[])
{
  // Create an image
  auto image =
    vtkSmartPointer<vtkImageData>::New();

  // Specify the size of the image data
  image->SetDimensions(50, 50, 1);
  image->AllocateScalars(VTK_FLOAT, 3);

  int* dims = image->GetDimensions();

  // Zero the image
  for (auto z = 0; z < dims[2]; ++z)
  {
    for (auto y = 0; y < dims[1]; ++y)
    {
      for (auto x = 0; x < dims[0]; ++x)
      {
        auto pixel = static_cast<float*>(image->GetScalarPointer(x, y, z));
        pixel[0] = 0.0;
        pixel[1] = 0.0;
        pixel[2] = 0.0;
      }
    }
  }

  {
    auto pixel = static_cast<float*>(image->GetScalarPointer(20, 20, 0));
    pixel[0] = -10.0;
    pixel[1] = 5.0;
  }

  {
    auto pixel = static_cast<float*>(image->GetScalarPointer(30, 30, 0));
    pixel[0] = 10.0;
    pixel[1] = 10.0;
  }

  // A better way to do this is (should be tested for compatibility and
  // correctness).
  // std::cout << image->GetPointData()->GetScalars()->GetName() << std::endl;
  image->GetPointData()->SetActiveVectors(
      image->GetPointData()->GetScalars()->GetName());
  // image->GetPointData()->SetActiveVectors("ImageScalars");

  // Setup the arrows
  auto arrowSource =
    vtkSmartPointer<vtkArrowSource>::New();
  arrowSource->Update();

  auto glyphFilter =
    vtkSmartPointer<vtkGlyph2D>::New();
  glyphFilter->SetSourceConnection(arrowSource->GetOutputPort());
  glyphFilter->OrientOn();
  glyphFilter->SetVectorModeToUseVector();
  glyphFilter->SetInputData(image);
  glyphFilter->Update();

  // Create actors
  auto imageMapper =
    vtkSmartPointer<vtkImageSliceMapper>::New();
  imageMapper->SetInputData(image);

  auto imageSlice =
    vtkSmartPointer<vtkImageSlice>::New();
  imageSlice->SetMapper(imageMapper);

  auto vectorMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  vectorMapper->SetInputConnection(glyphFilter->GetOutputPort());
  auto vectorActor =
    vtkSmartPointer<vtkActor>::New();
  vectorActor->SetMapper(vectorMapper);

  // Setup renderer
  auto renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddViewProp(imageSlice);
  renderer->AddViewProp(vectorActor);
  renderer->ResetCamera();

  // Setup render window
  auto renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  // Setup render window interactor
  auto renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  // auto style =
  //  vtkSmartPointer<vtkInteractorStyleImage>::New();
  // renderWindowInteractor->SetInteractorStyle(style);

  // Render and start interaction
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindow->Render();
  renderWindowInteractor->Initialize();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(VectorField)

find_package(VTK COMPONENTS 
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkFiltersCore
  vtkvtkFiltersSources
  vtkvtkIOXML
  vtkvtkInteractionStyle
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping VectorField: ${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(VectorField MACOSX_BUNDLE VectorField.cxx )
  target_link_libraries(VectorField PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(VectorField MACOSX_BUNDLE VectorField.cxx )
  target_link_libraries(VectorField PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS VectorField
    MODULES ${VTK_LIBRARIES}
    )
endif ()

cd VectorField/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./VectorField