1、前言

在UG NX三维建模过程中，创建基准坐标系是很重要的。基准坐标系是对于其他模型建模的一个参考，在UG NX中菜单中是由创建基准坐标系功能的，UG NX二次开发的创建基准坐标系的方法有两种，其可以通过UFun函数创建，也能通过NXOpen方法来实现，这篇介绍一下根据NXOpen方法来创建基准坐标系，下一篇介绍一下采用UFun函数来实现。有需要了解和讨论的可以私信博主，欢迎讨论。

2、UG NX中根据菜单来创建基准坐标系

2.1 打开UG NX

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2.2 打开基准坐标系创建界面

菜单->插入->基准->基准坐标系，如下图所示。
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2.3 根据两个轴和原点创建基准坐标系

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3、采用NXOpen方法来创建基准坐标系

3.1 创建创建基准坐标系的方法

其所需要的头文件为：

#include <uf_defs.h>
#include <NXOpen/NXException.hxx>
#include <NXOpen/Session.hxx>
#include <NXOpen/BasePart.hxx>
#include <NXOpen/Builder.hxx>
#include <NXOpen/CartesianCoordinateSystem.hxx>
#include <NXOpen/CoordinateSystemCollection.hxx>
#include <NXOpen/Direction.hxx>
#include <NXOpen/DirectionCollection.hxx>
#include <NXOpen/Expression.hxx>
#include <NXOpen/ExpressionCollection.hxx>
#include <NXOpen/Features_DatumCsysBuilder.hxx>
#include <NXOpen/Features_FeatureCollection.hxx>
#include <NXOpen/MeasureManager.hxx>
#include <NXOpen/NXObject.hxx>
#include <NXOpen/Part.hxx>
#include <NXOpen/PartCollection.hxx>
#include <NXOpen/Plane.hxx>
#include <NXOpen/PlaneCollection.hxx>
#include <NXOpen/Point.hxx>
#include <NXOpen/PointCollection.hxx>
#include <NXOpen/PreviewBuilder.hxx>
#include <NXOpen/Scalar.hxx>
#include <NXOpen/ScalarCollection.hxx>
#include <NXOpen/Session.hxx>
#include <NXOpen/SmartObject.hxx>
#include <NXOpen/Unit.hxx>
#include <NXOpen/UnitCollection.hxx>
#include <NXOpen/Xform.hxx>
#include <NXOpen/XformCollection.hxx>

首先声明一个方法

	void CreateCsys(Point3d point3D,Vector3d vector3D1,Vector3d vector3D2);

在定义此方法时的代码为：

void UFModel::CreateCsys(Point3d point3D, Vector3d vector3D1, Vector3d  vector3D2)
		{
        
            NXOpen::Session::UndoMarkId markId1;
            markId1 = theSession->SetUndoMark(NXOpen::Session::MarkVisibilityVisible, NXOpen::NXString("\350\265\267\347\202\271", NXOpen::NXString::UTF8));

            NXOpen::Features::Feature* nullNXOpen_Features_Feature(NULL);
            NXOpen::Features::DatumCsysBuilder* datumCsysBuilder1;
            datumCsysBuilder1 = workPart->Features()->CreateDatumCsysBuilder(nullNXOpen_Features_Feature);

    
            NXOpen::Point* point3;
            point3 = workPart->Points()->CreatePoint(point3D);

            NXOpen::Point3d origin1(0.0, 0.0, 0.0);           
            NXOpen::Direction* direction1;
            direction1 = workPart->Directions()->CreateDirection(origin1, vector3D1, NXOpen::SmartObject::UpdateOptionWithinModeling);
         
            NXOpen::Direction* direction2;
            direction2 = workPart->Directions()->CreateDirection(origin1, vector3D2, NXOpen::SmartObject::UpdateOptionWithinModeling);

            NXOpen::Xform* xform1;
            xform1 = workPart->Xforms()->CreateXform(point3, direction1, direction2, NXOpen::SmartObject::UpdateOptionWithinModeling, 1.0);
        
            NXOpen::CartesianCoordinateSystem* cartesianCoordinateSystem1;
            cartesianCoordinateSystem1 = workPart->CoordinateSystems()->CreateCoordinateSystem(xform1, NXOpen::SmartObject::UpdateOptionWithinModeling);
          
            datumCsysBuilder1->SetCsys(cartesianCoordinateSystem1);

            NXOpen::NXObject* nXObject1;
            nXObject1 = datumCsysBuilder1->Commit();
            datumCsysBuilder1->Destroy();
		}

3.2 在do_it方法中添加调用代码

	void UFModel::do_it()
		{
			Point3d point3D1(500,500,500);
			Vector3d vector3D1(0, 1, 0);
			Vector3d vector3D2(1, 0, 0);

			CreateCsys(point3D1,vector3D1,vector3D2);