title: How to implement "recalculate outside" in Blender
body: <p>When importing CAD file like STL format file, sometimes, some of the facets are reversed so their normal vectors are directing inside the volume while others going outside. the "recalculate outside" comes in to fix the situation.
  But, I am wondering how I can implement the function with CGAL. It would be appreciated if some guy show me the way about hint or code snippet.</p>
  
  <p>Thanks in advance.</p>