VisualizeStructuredGridCells

#include <vtkSmartPointer.h>

#include <vtkActor.h>
#include <vtkDataSetMapper.h>
#include <vtkMath.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkShrinkFilter.h>
#include <vtkStructuredGrid.h>
#include <vtkUnstructuredGrid.h>

int main(int, char *[])
{
  // Create a grid
  vtkSmartPointer<vtkStructuredGrid> structuredGrid =
    vtkSmartPointer<vtkStructuredGrid>::New();

  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
  unsigned int numi = 3;
  unsigned int numj = 4;
  unsigned int numk = 5;

  for(unsigned int k = 0; k < numk; k++)
  {
    for(unsigned int j = 0; j < numj; j++)
    {
      for(unsigned int i = 0; i < numi; i++)
      {
        points->InsertNextPoint(i, j, k);
      }
    }
  }

  // Specify the dimensions of the grid
  structuredGrid->SetDimensions(numi, numj, numk);
  structuredGrid->SetPoints(points);

  std::cout << "There are "
            << structuredGrid->GetNumberOfPoints() << " points before shrinking."
            << std::endl;
  std::cout << "There are "
            << structuredGrid->GetNumberOfCells() << " cells before shrinking."
            << std::endl;

  vtkSmartPointer<vtkShrinkFilter> shrinkFilter =
    vtkSmartPointer<vtkShrinkFilter>::New();
  shrinkFilter->SetInputData(structuredGrid);
  shrinkFilter->SetShrinkFactor(.8);
  shrinkFilter->Update();

  std::cout << "There are "
            << shrinkFilter->GetOutput()->GetNumberOfPoints() << " points after shrinking."
            << std::endl;
  std::cout << "There are "
            << shrinkFilter->GetOutput()->GetNumberOfCells() << " cells after shrinking."
            << std::endl;

  // Note: there are more points after shrinking because cells no longer share points.

  // Create a mapper and actor
  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  mapper->SetInputConnection(shrinkFilter->GetOutputPort());
  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  // Create a renderer, render window, and interactor
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(.2, .3, .4);

  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(VisualizeStructuredGridCells)

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

cd VisualizeStructuredGridCells/build

cmake ..

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

make

./VisualizeStructuredGridCells