[求助]：怎么样获得矩形,正n边形的中心?

win-gf

最好是中心的坐标...

谢谢啊

ljpnb

可以用面域求质心的坐标.

win-gf

生成面域之后怎么样获得质心坐标啊?

entget?


[PHP]
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ljpnb

[php]
(defun c:test (/ ent obj cen-point)
  (if (setq ent (car (entsel "\n选择一个正多边形:")))
    (progn
      (command "copy" ent "" "0,0" "@")
      (setq ent (entlast))
      (command "region" ent "")
      (setq ent        (entlast)
            obj        (vlax-ename->vla-object ent)
      )
      (setq cen-point (vlax-get obj 'Centroid))
      (vla-delete obj)
      (princ "\n 当前选择的正多边形的中心坐标为:")
      (princ cen-point)
    )
  )
  (princ)
)[/php]

xyp1964

2. [FONT=courier new]
   
3. (defun c:test ()
   
4.   (CMDLA0)
   
5.   (setq        ss (ssget)
   
6.         i  -1
   
7.   )
   
8.   (while (setq s1 (ssname ss (setq i (1+ i))))
   
9.     (if        (setq pt (xyp-get-center s1))
   
10.       (xyp-ZB pt 1000 4)
    
11.     )
    
12.   )
    
13.   (CMDLA1)
    
14. )[/FONT]

[FONT=courier new]<br /> (defun c:test ()<br />   (CMDLA0)<br />   (setq        ss (ssget)<br />         i  -1<br />   )<br />   (while (setq s1 (ssname ss (setq i (1+ i))))<br />     (if        (setq pt (xyp-get-center s1))<br />       (xyp-ZB pt 1000 4)<br />     )<br />   )<br />   (CMDLA1)<br /> )[/FONT]

win-gf

唉,看来还是需要学习啊.
to ljpnb  谢谢啊 受益匪浅
to xyp1964 我想做一个可以批量以各自中心scale多边形的程序给同事

但是用到函数库 太麻烦了

谢谢大家

呵呵

不知道可以不可以帮我完成批量以各自中心scale多边形的程序

最好不要用到xd的函数库

ljpnb

另一种方法(对正N边形有效)
[php]
(defun c:test (/ ss i scale ent ent1 lst cen-point)
  (command "undo" "be")
  (setvar "cmdecho" 0)
  (prompt "\n选择需要缩放的正N边形:")
  (setq        ss (ssget)
        i  -1
  )
  (while (setq ent (ssname ss (setq i (1+ i))))
    (redraw ent 3)
    )
  (setq i -1)
  (setq scale (getreal "\n输入比例系数:"))
  (while (setq ent (ssname ss (setq i (1+ i))))
    (setq
      lst (vl-remove-if '(lambda (x) (/= 10 (car x))) (entget ent))
    )
    (command "circle"
             "3p"
             (cdr (nth 0 lst))
             (cdr (nth 1 lst))
             (cdr (nth 2 lst))
    )
    (setq ent1 (entlast))
    (setq cen-point (cdr (assoc 10 (entget ent1))))
    (entdel ent1)
    (command "scale" ent "" "none" cen-point scale)
  )
  (command "undo" "e")
  (setvar "cmdecho" 1)
  (princ)
)

[/php]

yshf

求正n边形中心坐标的纯几何算法
[PHP];求正n边形中心坐标的纯几何算法
(defun c:cc()
   (setq cm (getvar "cmdecho"))(setvar "cmdecho" 0)
   (if (setq ent (car (entsel "\n请选择正n边形:")))
       (progn
          (setq ptb (vl-remove-if '(lambda(x)(/= 10 (car x))) (entget ent))
                n   (/ 1.0 (length ptb))
                pto '(0 0 0)
                ptb (vl-every '(lambda(x)(setq pto (mapcar '+ pto x))) ptb)
                pto (cdr (mapcar '* (list n n n) pto))
          )
          (princ (strcat "\n该正n边形的中心坐标：x=" (rtos (car  pto) 2 4)
                                               " y=" (rtos (cadr pto) 2 4)
                 )
          )
        )
   )
   (setvar "cmdecho" cm)(princ)
)[/PHP]

aeo

一般有规则的图案:
GetBoundingBox ,对角线的中点就是.

雨箭风刀

不对。举个例子：正三角形就不是。奇数角的正n边形都不是

taner

通過正n邊形的任意的三頂點畫圓,圓心就是其中心點.