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C# NX二次开发：曲线和点位相关UFUN函数详解

news 来源：原创 2025/8/15 11:26:26

大家好，今天要介绍查询曲线上点位和返回沿着曲线偏移一定距离的UFUN函数。

（1）UF_MODL_ask_curve_points：这个函数的定义为按照给定条件查询曲线上的点位。

Defined in: uf_modl_curves.h

Overview

Returns an array of 3D point coordinates (x,y,z) based on an input
curve, chordal tolerance, angular tolerance, and step tolerance.
A chord is the straight line between adjacent coordinates. The
tolerances provide independent values for controlling the output of
the coordinates located on the curve. The chordal tolerance (ctol) is
the maximum allowable distance from a chord to the curve between
the ends of the chord. The angular tolerance (atol) is the maximum
allowable sum of the angles between the chord and the tangents to the
curve at the ends of the chord. The step length (stol) is the maximum
allowable chordal length.

This routine does not create point objects as the GRIP and interactive
methods do.

If curve_id is an occurrence, then the points returned are relative to
the occurrence, and not the prototype.

Return

Error code:
0 = OK
1 = Invalid curve
2 = Modeler error

Note that this function treats the input "ctol" and "stol" tolerances
and returns point coordinates in the base units of the current displayed
part rather than the units of the part containing the input curve/edge.

In order it to return the expected coordinatesthe displayed part must be
set to the part containing the curve (or any other part using the units
of that part) and the display must have also been refreshed after setting
the new displayed part.

For example:

orig = UF_PART_ask_display_part();
UF_PART_ask_units(orig, &display_units);

UF_PART_ask_units(curve_owner, &units);
if (units != display_units)
{
UF_PART_set_display_part(curve_owner);
UF_DISP_refresh(); // required!
}
...
UF_MODL_ask_curve_points(curve, ...
...
UF_PART_set_display_part(orig);

Environment

Internal and External

tag_t	curve_id	Input	The identifier of the curve on which the points are to be determined.
double	ctol	Input	The chordal tolerance. 0= do not use chordal tolerance.
double	atol	Input	The angular tolerance in radians 0= do not use angular tolerance.
double	stol	Input	Maximum step length. 0 = do not use
int *	numpts	Output	Number of points in the points array.
double * *	pts	Output to UF_free	Pointer to the array containing the 3D points. The array returned is a single dimension array of size pts[3numpts]. The allocated arrays must be freed with UF_free.

double	point [ 3 ]	Input	Absolute coordinates of the reference point.
tag_t	curve	Input	Identifier of the selected curve.
double	offset	Input	Offset distance from the reference point along the selected curve.
int	direction	Input	Direction flag, 1=Same direction as the selected curve. (from start point to end point) -1=Reverse direction of the selected curve (from end point to start point)
double	tolerance	Input	Distance tolerance between solid edge and approximated curve.
double	point_along_curve [ 3 ]	Output	Absolute coordinates of the point on the curve at the offset distance.
double *	parameter	Output	Parameter value for the located point on the selected curve.

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