AutoCAD.Net/C#.Net QQ群:193522571 绘制椭圆及椭圆弧

这个椭圆好坑。

        /// <summary>
        /// 绘制椭圆及椭圆弧，注意当dX>dY时以X轴正方向为起始角，当dX<dY时以Y轴正方向为起始角
        /// </summary>
        /// <param name="db"></param>
        /// <param name="pt">椭圆中心点</param>
        /// <param name="dX">X轴轴长</param>
        /// <param name="dY">Y轴轴长</param>
        /// <param name="dStartAng">起始角（当dX>dY时以X轴正方向为起始角，当dX<dY时以Y轴正方向为起始角）</param>
        /// <param name="dEndAng">终止角（当dX>dY时以X轴正方向为起始角，当dX<dY时以Y轴正方向为起始角，注意方向为逆时针）</param>
        /// <returns></returns>
        public static ObjectId DrawEllipse(this Database db, Point3d pt,
                 double dX, double dY, double dStartAng = 0, double dEndAng = 360)
        {
            double dAngStart = dStartAng.DegreeToRadian();
            double dAngEnd = dEndAng.DegreeToRadian();

            //这个有点坑，长轴短轴要搞清楚
            Vector3d majorAxis = dX > dY ? new Vector3d(dX, 0, 0) : new Vector3d(0, dY, 0);
            //这个radio要弄清楚，必须小于1，不然就会出问题
            Ellipse ellipseArc = new Ellipse(pt, Vector3d.ZAxis, majorAxis, dX > dY ? dY / dX : dX / dY, dAngStart, dAngEnd);

            return db.AddToCurrentSpace(ellipseArc);
        }