public static double interiorAngle(Coordinate p0,Coordinate p1,Coordinate p2){
  double anglePrev=Angle.angle(p1,p0);
  double angleNext=Angle.angle(p1,p2);
  return Math.abs(angleNext - anglePrev);
}

public static double interiorAngle ( Coordinate p0 , Coordinate p1 , Coordinate p2 ) { double anglePrev = Angle . angle ( p1 , p0 ) ; double angleNext = Angle . angle ( p1 , p2 ) ; return Math . abs ( angleNext - anglePrev ) ; }
computes the interior angle between two segments of a ring . the ring is assumed to be oriented in a clockwise direction . the computed angle will be in the range [ 0 , 2pi ]
