INTERFACE EquaAngleEnergy;

IMPORT Energy;

TYPE
  T <: Public;
  Public = Energy.T OBJECT
    METHODS
      init(): T;
    END;
  (*
    The "Equalization Angle" energy measures the non-uniformity of diedral
    angles among consecutive faces incident to an internal edge "e". We say
    that an edge "e" is internal if every face incident to "e" is an inter-
    nal face. Analosgously, we say that a face "f" is internal if there exists
    exactely two tetrahedra incident to it. 

    This energy is computed only for edges that exist, are internal, have face
    ring degree  (DRF) three or more, and have only existing faces and vertices
    incident to it.

    The diedral angles not need projected. For two faces consecutives incidents
    to  same edge, the ideal angle "I" is "2*Pi/n" where "n" is the face ring
    degree correspondly to edge "e".

    Minimizing this energy tends to equalize the angles between consecutive
    faces incident to edge "e".

                        
                      f2  \    /f1
                           \  /
                            \/
			  e /\
			   /  \
			  /    \
                      f3         f4
			  
  *)
  
END EquaAngleEnergy.