daziran 发表于 2002-11-7 10:46:00

多段线问题

一条多段线，欲在距端点A长度处，画与该线正交的line ,如何做？

alin 发表于 2002-11-7 11:53:00

here...

Use the following visual lisp function can to that...
(vlax-curve-getparamatdist)-> to get the param at dist A
(vlax-curve-getpointatdist) -> to get the point
(vlax-curve-getfirstderiv) -> to get the first derivative at that point
The rest is easy.

龙龙仔 发表于 2002-11-7 15:57:00

程序....

(defun C:VV (/ HOLDORTH HOLDANG ENAME VL-OBJ X P PX1 JANG) ;HOLDOSMODE)
(vl-load-com)
;;(setq HOLDOSMODE (getvar "osmode"))
(setq HOLDORTH (getvar "orthomode"))
(setq HOLDANG (/ (* (getvar "snapang") 180) pi))
(setq        ENAME(car (entsel "\nSelect a valid curve: "))
        VL-OBJ (vlax-ename->vla-object ENAME)
)

(setq        X (vlax-curve-getparamatpoint
          VL-OBJ
          (setq P (vlax-curve-getclosestpointto
                      VL-OBJ
                      (vlax-curve-getpointatparam
                        VL-OBJ
                        (vlax-curve-getparamatdist
                          VL-OBJ
                          (getdist (vlax-curve-getstartpoint VL-OBJ)
                                   "\n距端點長度: "
                          )
                        )
                      )
                  )
          )
          )
)

;|
(setvar "osmode" 512)
(setq        X (vlax-curve-getparamatpoint
          VL-OBJ
          (setq P (vlax-curve-getclosestpointto
                      VL-OBJ
                      (getpoint "\nSelect point on curve: ")
                  )
          )
          )
)|;

(setq PX1 (vlax-curve-getfirstderiv VL-OBJ X))
(setq JANG (angle '(0 0 0) PX1))
(command "_.snapang" (/ (* JANG 180) pi))
(prompt "\nInput endpoint of line: ")
(setvar "orthomode" 1)
(command "_.line" P PAUSE "")
(setvar "orthomode" HOLDORTH)
(setvar "snapang" HOLDANG)
;;(setvar "osmode" HOLDOSMODE)
(princ)
)

daziran 发表于 2002-11-7 17:48:00

谢谢 Alin

daziran 发表于 2002-11-7 17:50:00

谢谢龙龙仔，非常好

alin 发表于 2002-11-7 23:35:00

已经收录。我想这会对搞道桥的有用吧。

曙光一号 发表于 2002-11-8 07:42:00

可以请教一个问题么？

用（vlax-curve-getparamatpoint curve-obj point) 返回的参数于于该point点是什么关系
（vlax-curve-getfirstderiv curve-obj param)返回的曲线在指定位置的第一个衍生于指定点又是什么关系
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