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NullPoint

vtk-examples/Cxx/PolyData/NullPoint

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Question

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Code

NullPoint.cxx

#include <vtkFloatArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkVersion.h>

#if VTK_VERSION_NUMBER >= 90000000000ULL
#define VTK_VER_GE_90 1
#endif

int main(int, char*[])
{
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(1, 1, 1);
  points->InsertNextPoint(2, 2, 2);
  points->InsertNextPoint(3, 3, 3);

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

  vtkNew<vtkFloatArray> floatArray;
  floatArray->SetNumberOfValues(3);
  floatArray->SetNumberOfComponents(1);
  floatArray->SetName("FloatArray");
  for (vtkIdType i = 0; i < 3; i++)
  {
    floatArray->SetValue(i, 2);
  }
  polydata->GetPointData()->AddArray(floatArray);

  vtkNew<vtkIntArray> intArray;
  intArray->SetNumberOfValues(3);
  intArray->SetNumberOfComponents(1);
  intArray->SetName("IntArray");
  for (vtkIdType i = 0; i < 3; i++)
  {
    intArray->SetValue(i, 2);
  }

  polydata->GetPointData()->AddArray(intArray);

  for (vtkIdType i = 0; i < 3; i++)
  {
    double p[3];
    polydata->GetPoint(i, p);
    vtkFloatArray* pointsFloatArray = dynamic_cast<vtkFloatArray*>(
        polydata->GetPointData()->GetArray("FloatArray"));
    vtkIntArray* pointsIntArray = dynamic_cast<vtkIntArray*>(
        polydata->GetPointData()->GetArray("IntArray"));
    std::cout << "Point " << i << " : " << p[0] << " " << p[1] << " " << p[2]
              << " " << pointsFloatArray->GetValue(i) << " "
              << pointsIntArray->GetValue(i) << std::endl;
  }

#if VTK_VER_GE_90
  polydata->GetPointData()->NullData(1);
#else
  polydata->GetPointData()->NullPoint(1);
#endif
  polydata->Modified();

  for (vtkIdType i = 0; i < 3; i++)
  {
    double p[3];
    polydata->GetPoint(i, p);
    vtkFloatArray* pointsFloatArray = dynamic_cast<vtkFloatArray*>(
        polydata->GetPointData()->GetArray("FloatArray"));
    vtkIntArray* pointsIntArray = dynamic_cast<vtkIntArray*>(
        polydata->GetPointData()->GetArray("IntArray"));
    std::cout << "Point " << i << " : " << p[0] << " " << p[1] << " " << p[2]
              << " " << pointsFloatArray->GetValue(i) << " "
              << pointsIntArray->GetValue(i) << std::endl;
  }

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(NullPoint)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  QUIET
)

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

Download and Build NullPoint

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

cd NullPoint/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:

./NullPoint

WINDOWS USERS

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