CenterOfMass

#include <vtkCenterOfMass.h>
#include <vtkDoubleArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>

#include <cmath>
#include <limits>

int main(int, char*[])
{
  // Create a point set of a square
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0, 0, 0);
  points->InsertNextPoint(1, 0, 0);
  points->InsertNextPoint(0, 1, 0);
  points->InsertNextPoint(1, 1, 0);

  vtkNew<vtkPolyData> polydata;
  polydata->SetPoints(points);

  // Compute the center of mass
  vtkNew<vtkCenterOfMass> centerOfMassFilter;
  centerOfMassFilter->SetInputData(polydata);
  centerOfMassFilter->SetUseScalarsAsWeights(false);
  centerOfMassFilter->Update();

  double center[3];
  centerOfMassFilter->GetCenter(center);

  std::cout << "Center of mass is " << center[0] << " " << center[1] << " "
            << center[2] << std::endl;

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(CenterOfMass)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  QUIET
)

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

cd CenterOfMass/build

cmake ..

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

make

./CenterOfMass