MARKUS

                                            List<Point> Points = GetRegularTrianglePoints(control.StartPoint, control.EndPoint);

                                            if (2 == Points.Count())

                                            {

                                                control.MidPoint = Points[0];

                                                control.EndPoint = Points[1];

                                            }

        /// <summary>

        /// 정삼각형을 그리기위한 두 포인트를 계산하여 넘겨줌

        /// </summary>

        /// <author>humkyung</author>

        /// <date>2018.04.26</date>

        /// <param name="StartP"></param>

        /// <param name="EndP"></param>

        /// <returns></returns>

        private List<Point> GetRegularTrianglePoints(Point StartP, Point EndP)

        {

            List<Point> res = new List<Point>();

            double dx = EndP.X - StartP.X;

            double dy = EndP.Y - StartP.Y;

            double length = Math.Sqrt(dx * dx + dy * dy);

            double baseLength = length * Math.Tan(30.0* Math.PI / 180.0);

            dx /= length;

            dy /= length;

            double tmp = dx;

            dx = -dy; dy = tmp; /// rotate by 90 degree

            res.Add(new Point(EndP.X + dx * baseLength, EndP.Y + dy * baseLength));

            res.Add(new Point(EndP.X - dx * baseLength, EndP.Y - dy * baseLength));

            return res;

        }