C＃ autoCAD 几个经常用到的功能代码。

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace 块
{
    static class Class2
    {
        /// <summary>
        /// 判断点是否重合
        /// </summary>
        /// <param name="p1">点1</param>
        /// <param name="p2">点2</param>
        /// <param name="allowance">容差</param>
        /// <returns></returns>
        public static Boolean Coincide( this Point3d p1, Point3d p2, Double allowance)
        {
            if (p1.DistanceTo(p2) < allowance)
                return true;
            else
                return false;
        }


        /// <summary>
        /// 判断点是否在直线上
        /// </summary>
        /// <param name="line">直线</param>
        /// <param name="point1">点</param>
        /// <param name="allowance">容差</param>
        /// <returns></returns>
        public static  Boolean Coincide(this Line line, Point3d point1, Double allowance)
        {
            Point3d p1 = line.StartPoint;
            Point3d p2 = line.EndPoint;
            //叉积是否为allowance，判断是否在同一直线上
            if (Math.Abs((p1.X - point1.X) * (p2.Y - point1.Y) - (p2.X - point1.X) * (p1.Y - point1.Y)) < allowance)
            {
                return true;
            }
            else
            {
                return false;
            }
        }


        /// <summary>
        /// 判断两条直线是否重合
        /// </summary>
        /// <param name="line1">线1</param>
        /// <param name="line2">线2</param>
        /// <param name="allowance">容差</param>
        /// <returns></returns>
        public static  Boolean Coincide(this Line line1, Line line2, Double allowance)
        {
            LineSegment3d l1 = new LineSegment3d(line1.StartPoint, line1.EndPoint);
            LineSegment3d l2 = new LineSegment3d(line2.StartPoint, line2.EndPoint);
            Tolerance tol = new Tolerance(allowance, allowance);
            return l1.IsColinearTo(l2, tol);
        }

        /// <summary>
        /// 空间两点之间距离
        /// </summary>
        /// <param name="point1">点1</param>
        /// <param name="point2">点2</param>
        /// <param name="Decimal">小数位数</param>
        /// <returns></returns>
        public static Double Distance(this Point3d point1, Point3d point2, Int16 Decimal)
        {
            Double a = point1.X - point2.X;
            Double b = point1.Y - point2.Y;
            Double c = point1.Z - point2.Z;
            Double r = a * a + b * b + c * c;
            return Math.Round(Math.Abs(Math.Sqrt(r)), Decimal);
        }


        /// <summary>
        /// 获得空间点到空间线段的垂直距离
        /// </summary>
        /// <param name="line">直线</param>
        /// <param name="pt">空间的点</param>
        /// <param name="Decimal">小数位数</param>
        /// <returns>点到直线垂直距离</returns>
        public static  Double Distance(Line line, Point3d pt, Int16 Decimal)
        {
            Double t;
            if (line != null)
            {
                Point3d StartPoint = line.StartPoint;
                Point3d EndPoint = line.EndPoint;
                //直线方向向量
                Point3d dir = new Point3d(StartPoint.X - EndPoint.X, StartPoint.Y - EndPoint.Y, StartPoint.Z - EndPoint.Z);
                //过点且与直线垂直的平面
                t = -(Double)(dir.X * (StartPoint.X - pt.X) + dir.Y * (StartPoint.Y - pt.Y) + dir.Z * (StartPoint.Z - pt.Z)) / (dir.X * dir.X + dir.Y * dir.Y + dir.Z * dir.Z);
                //过点的垂直于直线的平面与该直线的交点
                Point3d fp = new Point3d(StartPoint.X + dir.X * t, StartPoint.Y + dir.Y * t, StartPoint.Z + dir.Z * t);
                return Distance(pt, fp, Decimal);
            }
            else
            {
                return 0;
            }
        }

        /// <summary>
        /// 中点
        /// </summary>
        /// <param name="StartPoint">起点</param>
        /// <param name="EndPoint">终点</param>
        /// <returns></returns>
        public static Point3d Midpoint(this Point3d StartPoint, Point3d EndPoint)
        {
            Double x = (StartPoint.X + EndPoint.X) / 2;
            Double y = (StartPoint.Y + EndPoint.Y) / 2;
            Double z = (StartPoint.Z + EndPoint.Z) / 2;
            return new Point3d(x, y, z);
        }


        public static double AngleFromXAxis(this Point3d pt1, Point3d pt2)
        { 
            Vector2d vector=new Vector2d(pt1.X-pt2.X, pt1.Y-pt2.Y);
            return vector.Angle;
        }
        /// <summary>
        ///  角度转换弧度
        /// </summary>
        /// <param name="degree">角度制</param>
        /// <returns></returns>
        public static double DegreeToAngle(this Double degree)
        {
            return degree * Math.PI / 180;
        }
        /// <summary>
        /// 弧度转换角度
        /// </summary>
        /// <param name="angle">弧度制</param>
        /// <returns></returns>
        public static double AngleToDegree(this Double angle)
        {
            return angle * 180 / Math.PI;
        }


        /// <summary>
        /// 环形阵列
        /// </summary>
        /// <param name="entId">图形对象的ObjectId</param>
        /// <param name="num">图形数量</param>
        /// <param name="degree">中心点到各个图形的夹角</param>
        /// <param name="center">中心点</param>
        /// <returns>List</returns>  已经加入图形数据库
        public static List<Entity> ArrayPolarEntity(this ObjectId entId, int num, double degree, Point3d center)
        {
            // 声明一个List集合 用于返回
            List<Entity> entList = new List<Entity>();
            // 打开事务处理
            using (Transaction trans = entId.Database.TransactionManager.StartTransaction())
            {
                // 打开块表
                BlockTable bt = (BlockTable)trans.GetObject(entId.Database.BlockTableId, OpenMode.ForRead);
                // 打开块表记录
                BlockTableRecord btr = (BlockTableRecord)trans.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
                Entity ent = (Entity)entId.GetObject(OpenMode.ForWrite);
                // 限定阵列角度大小
                degree = degree > 360 ? 360 : degree;
                degree = degree < -360 ? 360 : degree;
                int divAngnum = num - 1;
                if (degree == 360 || degree == -360)
                {
                    divAngnum = num;
                }
                // 计算变换矩阵
                for (int i = 0; i < num; i++)
                {
                    Matrix3d mt = Matrix3d.Rotation((i * degree / divAngnum).DegreeToAngle(), Vector3d.ZAxis, center);
                    Entity entA = ent.GetTransformedCopy(mt);
                    btr.AppendEntity(entA);
                    trans.AddNewlyCreatedDBObject(entA, true);
                    entList.Add(entA);
                }
                ent.Erase();
                trans.Commit();
            }
            return entList;
        }
    }
}