public static void Fan()
{
Database db = HostApplicationServices.WorkingDatabase;
using (Transaction trans = db.TransactionManager.StartTransaction())
{
// 定义圆弧上的三个点
Point3d startPoint = new Point3d(100, 0, 0);
Point3d pointOnArc = new Point3d(50, 25, 0);
Point3d endPoint = new Point3d();
// 调用三点法画圆弧的扩展函数创建扇形的圆弧
Arc arc = new Arc();
arc.CreatArc(startPoint, pointOnArc, endPoint);
// 创建扇形的两条半径
Line line1 = new Line(arc.Center, startPoint);
Line line2 = new Line(arc.Center, endPoint);
// 添加实体到模型空间，完成扇形的创建
db.AddToModelSpace(line1);
db.AddToModelSpace(line2);
db.AddToModelSpace(arc);
trans.Commit();
}
}
