关于UF_MODL_ask_face_props

请问它的参数里面，哪个是输入，哪个是输出？

UF_MODL_ask_face_props


extern void uf5911 (
tag_t * np1,
double * rp2,
double * rr3,
double * rr4,
double * rr5,
double * rr6 );

这几个参数都什么含义阿？

谢谢

int UF_MODL_ask_face_props
(
tag_t face_id,
double param [ 2 ] ,
double point [ 3 ] ,
double u1 [ 3 ] ,
double v1 [ 3 ] ,
double u2 [ 3 ] ,
double v2 [ 3 ] ,
double unit_norm [ 3 ] ,
double radii [ 2 ]

)

tag_t	face_id	Input	Face identifier.
double	param [ 2 ]	Input	Parameter (u,v) on face (param[2]).
double	point [ 3 ]	Output	Point at parameter (point[3]).
double	u1 [ 3 ]	Output	First derivative in U (u1[3]).
double	v1 [ 3 ]	Output	First derivative in V (v1[3]).
double	u2 [ 3 ]	Output	Second derivative in U (u2[3]).
double	v2 [ 3 ]	Output	Second derivative in V (v2[3]).
double	unit_norm [ 3 ]	Output	Unit face normal (unit_norm[3]).
double	radii [ 2 ]	Output	Principal radii of curvature (radii[2]).