title: Winged-edge vs half-edge
body: <p>I try to understand boundary representation (B-rep) and I cannot find what's the advantages of the half-edge data structure versus the winged-edge one. I've found in <a href="http://link.springer.com/book/10.1007/978-3-642-45729-6" rel="nofollow">this book</a> that winged-edge cannot represent the state where a vertex but no edges exists in space. But there is no sample. </p>
  
  <p><a href="https://books.google.fr/books?id=bIoWorFdmBkC&amp;pg=PA190&amp;lpg=PA190&amp;dq=limitation%20of%20winged%20edge%20data%20structure&amp;source=bl&amp;ots=NNqg5p1ebe&amp;sig=N-zJOcaNIGf2za453nMvQwLE_Mo&amp;hl=fr&amp;sa=X&amp;ved=0ahUKEwi8m_CQqobKAhUB2RQKHfnmAJgQ6AEIPTAE#v=onepage&amp;q=limitation%20of%20winged%20edge%20data%20structure&amp;f=false" rel="nofollow">Another book</a> says that there is an ambiguity in the edge direction. </p>
  
  <p>And finally, on a <a href="http://www.flipcode.com/archives/The_Half-Edge_Data_Structure.shtml" rel="nofollow">this web page</a>, performance reasons are invoked.</p>