net cad具体代码

下面是一个简单的使用C#语言编写的.NET平台上的CAD应用程序的代码示例：

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;

namespace MyCADApp
{
    public class MyCommands
    {
        [CommandMethod("MyLine")]
        public void MyLine()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
                BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);

                PromptPointOptions ppo = new PromptPointOptions("\nStart point: ");
                PromptPointResult ppr = ed.GetPoint(ppo);
                if (ppr.Status != PromptStatus.OK) return;
                Point3d startPt = ppr.Value;

                ppo.Message = "\nEnd point: ";
                ppr = ed.GetPoint(ppo);
                if (ppr.Status != PromptStatus.OK) return;
                Point3d endPt = ppr.Value;

                Line line = new Line(startPt, endPt);

                btr.AppendEntity(line);
                tr.AddNewlyCreatedDBObject(line, true);

                tr.Commit();
            }
        }
    }
}

这个代码示例实现了一个简单的绘制直线的命令，在AutoCAD中输入"MyLine"命令即可调用该命令。在该命令中，使用了AutoCAD的API来获取当前文档、数据库、编辑器等对象，并使用事务来管理绘图操作。具体的绘图操作包括获取起点和终点坐标、创建直线对象、将直线对象添加到模型空间中等。