对克隆实体的类型转换
AcDbEntity *pEnt;
acdbOpenAcDbEntity(pEnt, pId, AcDb::kForRead);
AcRxObject *pObj = NULL;
pObj = pEnt->clone();
AcDbEntity *pEntT = static_cast<AcDbEntity*>(pObj);
第二种
AcRxObject *obj = pPolyline->clone();
AcDbPolyline *newPoly = new AcDbPolyline();
newPoly =AcDbPolyline::cast(obj);