[ARX程序]：曲线上的垂直线！

fylinwater

最初由 RedCAD 发布
[B]你这个函数能得出曲线上任意点的切线角度吗？ [/B]

getFirstDeriv不就是求一次导数？

RedCAD

哦，以前没用过，非常感谢，这可是一个非常重要的函数啊

wkur

getFirstDeriv求导，在旋转就可以了，不用费那么大劲

missyou0515

XD回答过这个问题，转述如下
1、首先用：

[PHP]virtual Acad::ErrorStatus getFirstDeriv( const AcGePoint3d& unnamed, AcGeVector3d& firstDeriv) const;
[/PHP]

unnamed Input point on curve at which to find the first derivative

firstDeriv Returns the first derivative of the curve at point

This function evaluates the first derivative of the curve at point and sets

firstDeriv to the result, in both this class and derived classes. Both point

and firstDeriv are in WCS coordinates in derived classes.

Returns Acad::eOk if successful. If point is not on the curve, then

Acad::eInvalidInput is returned. Other ErrorStatus return values are up to

the implementor.


For implementation, the AcGe classes may provide some of the necessary

functionality to make the job easier.

In the default implementation, the function returns Acad::eNotImplemented

得到曲线在该点p1的一阶导数（切线矢量）vec1

2、由vec1使用：

[PHP]AcGeVector3d::perpVector Function AcGeVector3d

perpVector() const; [/PHP]

Returns a vector orthogonal to this vector. The choice of the orthogonal

vector is determined by the function

得到垂向量vec2 后，那么过曲线任一点的“垂线”也就得到了。 　
我认为ARX编程最高效的地方就在于这个AcGe几何库。

leagoti

恩,不错的一个函数getFirstDeriv.



virtual Acad::ErrorStatus getFirstDeriv( const AcGePoint3d& unnamed, AcGeVector3d& firstDeriv) const;

firstDeriv 的值:
凸度为零的直线:firstDeriv.x和firstDeriv.y是沿直线方向,直线的长度在x,y上的投影值;
凸度非零的圆弧:firstDeriv.x和firstDeriv.y是沿切线方向,半径的长度在x,y上的投影值;

boaosun

不错,好东西!

mcfield

missyou0515 发表于 2006-8-22 08:53
XD回答过这个问题，转述如下
1、首先用：

getFirstDeriv函数只在AcDb库中，AcGe库中没有。