[求助]：请教如何将PL线投影到凹凸不平的3DMESH上

matichen

想构造贴合3DMESH面的用地边界，只有PL线。该如何做，LISP能行吗？

eachy

Returns the closest point (in WCS) on a curve after projecting the curve onto a plane

(vlax-curve-getClosestPointToProjection curve-obj givenPnt normal [extend])

Arguments

curve-obj

The VLA-object to be measured.

givenPnt

A point (in WCS) for which to find the nearest point on the curve.

normal

A normal vector (in WCS) for the plane to project onto.

extend

If specified and not nil, vlaxcurvegetClosestPointToProjection extends the curve when searching for the nearest point.

vlaxcurvegetClosestPointToProjection projects the curve onto the plane defined by the givenPnt and normal, and then calculates the nearest point on that projected curve to givenPnt. The resulting point is then projected back onto the original curve, and vlaxcurvegetClosestPointToProjection returns that projected point.

Return Values

A 3D point list representing a point on the curve, if successful; otherwise nil.

   Comments?

matichen

Y斑竹，我英语不好，看不太明白，能帮忙解释下吗，还有，好像要用到VLAX吧，我只能凑合搞点LISP，V-LISP没怎么入门，还望不吝多指导下。

eachy

最初由 matichen 发布
[B]Y斑竹，我英语不好，看不太明白，能帮忙解释下吗，还有，好像要用到VLAX吧，我只能凑合搞点LISP，V-LISP没怎么入门，还望不吝多指导下。 [/B]

用 Vlax-curve 部分函数是最简单直接的，否则你还得去学习解析几何、曲面方程、投影变换等等。或者去使用XDAPI提供的几何类函数。想学好Lisp，去适应这些E文吧，不要害怕。