ReverseSense

VTKExamples/Cxx/PolyData/ReverseSense

Question

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Code

ReverseSense.cxx

#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkPointData.h>
#include <vtkReverseSense.h>
#include <vtkFloatArray.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->Update();

  vtkSmartPointer<vtkFloatArray> pointNormals =
    dynamic_cast<vtkFloatArray*>(sphereSource->GetOutput()->GetPointData()->GetNormals());

  std::cout << std::endl << "Normals: " << std::endl;
  // Display the first few normals
  for(unsigned int i = 0; i < 5; i++)
  {
    double pN[3];
    pointNormals->GetTuple(i, pN);
    std::cout << "Point normal " << i << ": " << pN[0] << " " << pN[1] << " " << pN[2] << std::endl;
  }

  vtkSmartPointer<vtkReverseSense> reverseSense =
    vtkSmartPointer<vtkReverseSense>::New();
  reverseSense->SetInputConnection(sphereSource->GetOutputPort());
  reverseSense->ReverseNormalsOn();
  reverseSense->Update();


  vtkSmartPointer<vtkFloatArray> reversedNormals =
    dynamic_cast<vtkFloatArray*>(reverseSense->GetOutput()->GetPointData()->GetNormals());

  std::cout << std::endl << "Reversed: " << std::endl;
  // Display the first few normals to verify that they are flipped
  for(unsigned int i = 0; i < 5; i++)
  {
    double pN[3];
    reversedNormals->GetTuple(i, pN);
    std::cout << "Reversed normal " << i << ": " << pN[0] << " " << pN[1] << " " << pN[2] << std::endl;
  }

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ReverseSense)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkFiltersSources QUIET)
if (NOT VTK_FOUND)
  message("Skipping ReverseSense: ${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(ReverseSense MACOSX_BUNDLE ReverseSense.cxx )
  target_link_libraries(ReverseSense PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ReverseSense MACOSX_BUNDLE ReverseSense.cxx )
  target_link_libraries(ReverseSense PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ReverseSense
    MODULES ${VTK_LIBRARIES}
    )
endif () 

Download and Build ReverseSense

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

cd ReverseSense/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:

./ReverseSense

WINDOWS USERS

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