请问有人知道如何获取曲线或者边界端点的切线矢量吗？

曲线或者边界，一般都有两个端点

其几何属性通过分析菜单是可以查得到的

不知道用API如何获取？

谢谢

这里有：

UF_MODL_ask_curve_props [url=mkMSITStore:E:\UGS\NX%206.0\UGDOC\html_files\nxopen_net_ref\net_ref.chm::/ugopen_doc/uf_modl/uf_modl_curves.html#UF_MODL_ask_curve_props](view source)[/url]


Defined in: uf_modl_curves.h


Overview

Returns the point, tangent, unit principal normal, unit binormal,
torsion, and radius of curvature on a curve at a given parameter.
The input curve parameter, parm, is normalized between 0 and 1.

UF_EVAL_evaluate should be used to evaluate curves and edges instead
of using this routine. For a full circle, the routines may return
different results, as the parameterization of the circle may be done in
two different directions.


Environment

Internal and External


See Also

[url=mkMSITStore:E:\UGS\NX%206.0\UGDOC\html_files\nxopen_net_ref\net_ref.chm::/ugopen_doc/uf_eval/global.html#UF_EVAL_evaluate]UF_EVAL_evaluate[/url]


Required License(s)

gateway


int UF_MODL_ask_curve_props
(
tag_t curve_id,
double parm,
double point [ 3 ] ,
double tangent [ 3 ] ,
double p_norm [ 3 ] ,
double b_norm [ 3 ] ,
double * torsion,
double * rad_of_cur

)

[url=mkMSITStore:E:\UGS\NX%206.0\UGDOC\html_files\nxopen_net_ref\net_ref.chm::/ugopen_doc/uf_defs/uf_defs.html#tag_t]tag_t[/url]	curve_id	Input	Curve identifier.
double	parm	Input	Curve parameter.
double	point [ 3 ]	Output	Point on curve (3 element array).
double	tangent [ 3 ]	Output	Tangent of curve (3 element array).
double	p_norm [ 3 ]	Output	Unit Principal normal of curve (3 element array).
double	b_norm [ 3 ]	Output	Unit Binormal of curve (3 element array).
double *	torsion	Output	Torsion.
double *	rad_of_cur	Output	Radius of Curvature.

其中第二个参数取值范围从0到1.
为0，表示起点信息，为1，表示终点信息

谢谢！

我用NXOpen的AnalysisManager类做的（这个操作录制能录制到），但是在裁剪过的曲线一个端点总是出现巨大的数

所以只好找API试试

非常感谢！

学习了学习了。