code: function ( degree, point, center ) {
              var angle = 0;
      
              if ( this._degree !== degree ) {
                  //중심점 기준의 좌표로 보정
                  var ox = this._pointX - this._centerX,
                      oy = this._pointY - this._centerY,
                      nx = point.x - center.x,
                      ny = point.y - center.y,
                      cw = this._isClockwise( ox , oy, nx, ny );
      
                  if ( cw ) {
                      if ( degree < this._degree ) {
                          angle = ( 360 - this._degree ) + degree;
                      } else {
                          angle = degree - this._degree;
                      }
                  } else {
                      if ( degree < this._degree ) {
                          angle = -( this._degree - degree );
                      } else {
                          angle = -( this._degree + (360 - degree) );
                      }
                  }
              }
      
              return angle;
          }
docs: 변화된 각도양 반환