https://www.cnblogs.com/gisoracle/archive/2012/02/19/2357925.html

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.DatabaseServices;
using
 
 Autodesk.AutoCAD.Geometry;

 

namespace MyFirstProject
{
    public class Class1
    {
        [CommandMethod("HelloNet")]
        public void HelloNet()
        {
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            ed.WriteMessage("使用NET開發AutoCAD 程序bygisoracle
 
");
        }
        [CommandMethod("PickPoint")]
        public void PickPoint()
        {
            //獲取Editor 對象
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            PromptPointOptions promptPtOp = new PromptPointOptions("選擇一個點：");
            //指定的基點，如果指定了該點，則在選擇的時候繪制一條橡皮線。
 

            promptPtOp.BasePoint = new Autodesk.AutoCAD.Geometry.Point3d(0, 0, 0);
            PromptPointResult resPt;
            resPt = ed.GetPoint(promptPtOp);
            if (resPt.Status == PromptStatus.OK)
            {
                ed.WriteMessage(" 選擇的點為： " + resPt.Value.ToString());
            }

        }
        [CommandMethod("createCircle")]
        public void createCircle()
        {
           
            //首先聲明我們要使用的對象
            Circle circle; //這個是我們要加入到模型空間的圓
            BlockTableRecord btr;//要加入圓，我們必須打開模型空間
            BlockTable bt; //要打開模型空間，我們必須通過塊表(BlockTable)來訪問它

            //我們使用一個名為‘Transaction’的對象，把函數中有關數據庫的操作封裝起來
            Transaction trans;

            //使用TransactionManager的StartTransaction()成員來開始事務處理
            trans = HostApplicationServices.WorkingDatabase.TransactionManager.StartTransaction();

            //現在創建圓……請仔細看這些參數——註意創建Point3d對象的‘New’和Vector3d的靜態成員ZAxis
            circle = new Circle(new Point3d(10, 10, 0), Vector3d.ZAxis, 2);
            bt = (BlockTable)trans.GetObject(HostApplicationServices.WorkingDatabase.BlockTableId, OpenMode.ForRead);

            //使用當前的空間Id來獲取塊表記錄——註意我們是打開它用來寫入
            btr = (BlockTableRecord)trans.GetObject(HostApplicationServices.WorkingDatabase.CurrentSpaceId, OpenMode.ForWrite);

            //現在使用btr對象來加入圓
            btr.AppendEntity(circle);
            trans.AddNewlyCreatedDBObject(circle, true); //並確定事務處理知道要加入圓！

            //一旦完成以上操作，我們就提交事務處理，這樣以上所做的改變就被保存了……
            trans.Commit();

            //…然後銷毀事務處理，因為我們已經完成了相關的操作（事務處理不是數據庫駐留對象，可以銷毀）
            trans.Dispose();

        }
        [CommandMethod("SelectAPoint")]
        public void SelectAPoint()
        {
            //實例化一個 PromptPointOptions類用來設置提示字符串和其他的一些控制提示
            PromptPointOptions prPointOptions = new PromptPointOptions("Select a point");
            PromptPointResult prPointRes;
            // 實例化一個Editor類，使用GetPoint方法返回
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            prPointRes = ed.GetPoint(prPointOptions);
            if (prPointRes.Status != PromptStatus.OK)
            {
                ed.WriteMessage("Error");
            }
            else
            {
                ed.WriteMessage("選擇的點為：" + prPointRes.Value.ToString());
            }
        }
        [CommandMethod("getDistance")]
        public void GetDistance()
        {
            PromptDistanceOptions prDistOptions = new
            PromptDistanceOptions("計算兩點距離，請選擇第一個點：");
            PromptDoubleResult prDistRes;
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            prDistRes = ed.GetDistance(prDistOptions);
            if (prDistRes.Status != PromptStatus.OK)
            {
                ed.WriteMessage("選擇錯誤！");
            }
            else
            {
                ed.WriteMessage("兩點的距離為：" + prDistRes.Value.ToString());
            }
        }
        [CommandMethod("AddPointAndSetPointStyle")]

        public static void AddPointAndSetPointStyle()
        {
            // 獲得當前文檔和數據庫   Get the current document and database
            Document acDoc = Application.DocumentManager.MdiActiveDocument;
            Database acCurDb = acDoc.Database;

            // 啟動一個事務  Start a transaction
            using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
            {
                // 以只讀方式打開塊表   Open the Block table for read
                BlockTable acBlkTbl;
                acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                             OpenMode.ForRead) as BlockTable;

                // 以寫方式打開模型空間塊表記錄   Open the Block table record Model space for write
                BlockTableRecord acBlkTblRec;
                acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                                OpenMode.ForWrite) as BlockTableRecord;

                // 在模型空間中創建一個坐標為（4，3，0）的點   Create a point at (4, 3, 0) in Model space
                for (int i = 0; i < 100; i++)
                {
                    DBPoint acPoint = new DBPoint(new Point3d(4*i, 3, 0));

                    acPoint.SetDatabaseDefaults();

                    // 添加新對象到塊表記錄和事務中   Add the new object to the block table record and the transaction
                    acBlkTblRec.AppendEntity(acPoint);
                    acTrans.AddNewlyCreatedDBObject(acPoint, true);
                }
              

                // 在圖形中設置所有點對象的樣式   Set the style for all point objects in the drawing
                acCurDb.Pdmode = 34;
                acCurDb.Pdsize = 1;

                // 保存新對象到數據庫中   Save the new object to the database
                acTrans.Commit();
            }
        }
        [CommandMethod("Add2DSolid")]
        public static void Add2DSolid()
        {
            // 獲得當前文檔和數據庫   Get the current document and database
            Document acDoc = Application.DocumentManager.MdiActiveDocument;
            Database acCurDb = acDoc.Database;

            // 啟動一個事務  Start a transaction
            using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
            {
                // 以只讀方式打開塊表   Open the Block table for read
                BlockTable acBlkTbl;
                acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                             OpenMode.ForRead) as BlockTable;

                // 以寫方式打開模型空間塊表記錄   Open the Block table record Model space for write
                BlockTableRecord acBlkTblRec;
                acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                                OpenMode.ForWrite) as BlockTableRecord;

                // Create a quadrilateral (bow-tie) solid in Model space
               
                Solid ac2DSolidBow = new Solid(new Point3d(0, 0, 0),
                                               new Point3d(5, 0, 0),
                                               new Point3d(5, 8, 0),
                                               new Point3d(0, 8, 0));

                ac2DSolidBow.SetDatabaseDefaults();

                // 添加新對象到塊表記錄和事務中   Add the new object to the block table record and the transaction
                acBlkTblRec.AppendEntity(ac2DSolidBow);
                acTrans.AddNewlyCreatedDBObject(ac2DSolidBow, true);

                // Create a quadrilateral (square) solid in Model space
                Solid ac2DSolidSqr = new Solid(new Point3d(10, 0, 0),
                                               new Point3d(15, 0, 0),
                                               new Point3d(10, 8, 0),
                                               new Point3d(15, 8, 0));

                ac2DSolidSqr.SetDatabaseDefaults();

                // 添加新對象到塊表記錄和事務中   Add the new object to the block table record and the transaction
                acBlkTblRec.AppendEntity(ac2DSolidSqr);
                acTrans.AddNewlyCreatedDBObject(ac2DSolidSqr, true);

                // 保存新對象到數據庫中   Save the new object to the database
                acTrans.Commit();
            }
        }

        [CommandMethod("AddLine")]
        public static void AddLine()
        {
            // 獲得當前文檔和數據庫   Get the current document and database
            Document acDoc = Application.DocumentManager.MdiActiveDocument;
            Database acCurDb = acDoc.Database;

            // 啟動一個事務  Start a transaction
            using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
            {
                // 以只讀方式打開塊表   Open the Block table for read
                BlockTable acBlkTbl;
                acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                             OpenMode.ForRead) as BlockTable;

                // 以寫方式打開模型空間塊表記錄   Open the Block table record Model space for write
                BlockTableRecord acBlkTblRec;
                acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                                OpenMode.ForWrite) as BlockTableRecord;

                // 創建一條起點為（5，5，0），終點為（12，3，0）的直線  Create a line that starts at 5,5 and ends at 12,3
                Line acLine = new Line(new Point3d(5, 5, 0),
                                       new Point3d(12, 3, 0));

                acLine.SetDatabaseDefaults();

                // 添加新對象到塊表記錄和事務中   Add the new object to the block table record and the transaction
                acBlkTblRec.AppendEntity(acLine);
                acTrans.AddNewlyCreatedDBObject(acLine, true);

                // 保存新對象到數據庫中   Save the new object to the database
                acTrans.Commit();
            }


        }
    }
}

AutoCAD C#二次開發