线段等分/定长的实现

//方法名称:GetPointAtDist
//拥有者:Curve（基类）及line arc polyline…
//返回值:point3d
//功能描述:返回曲线上距起点某距离值处的点。
//类似方法：GetParameterAtDistance
//相关备注：线段总长方法仅仅在子类中才有，基类没有
比如：arc.Length line.Length polyline.Length

范例：在CAD中对PLine（line arc 同样适用）线段按给定长度进行标志点(等分)

private void My_div() // 求等分点或定长点
            {
   
 Autodesk.AutoCAD.ApplicationServices.Document acDoc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
                Editor ed = acDoc.Editor;
                Database acCurDb = acDoc.Database;
                Entity acEnt = null;
                Curve curve = null;
                Polyline polyline = null;