大家有没有发现 GetBoundingBox 有时对spline求不出正确的结果。

congcong

大家有没有发现 GetBoundingBox 有时对spline求不出正确的结果。
我编了两个程序，两个程序在对spline执行过程中有时候正确，有时候又不正确。一步一步跟踪就会发现 GetBoundingBox 会传回来错误的数值。
而对其它的图元都没有问题。
不知道大家有没有遇到过这样的情况。

meflying

你把测试的程序和出错的测试图给一个看看

congcong

图上的多义线都算错了，其它的图，如圆，线，及多段线都算正确了。
下面是源代码
(defun c:test(/ st js pt_list pt1 pt2)
  (SETQ st (SSGET '(( 0 . "line,circle,arc,LWPOLYLINE,SPLINE,ELLIPSE"))))
  (vl-cmdf ".ucs" "")
  (setvar "osmode" 0)
  
  (setq js 0  pt_list nil)
  (repeat (sslength st)
    (setq PT_LIST (append PT_LIST (AX:GETBOUNDINGBOX (ssname st js))))
    (setq js (1+ js))
    )
  (setq PT1 (list (apply 'min (mapcar 'car  PT_LIST))
                  (apply 'min (mapcar 'cadr PT_LIST))
                  )
        PT2 (list (apply 'max (mapcar 'car  PT_LIST))
                  (apply 'max (mapcar 'cadr PT_LIST))
                  )     
            )
  (vl-cmdf ".RECTANG" pt1 pt2)
  )

congcong

这个是上面那个程序的 AX:GETBOUNDINGBOX 函数的源代码
(defun AX:GETBOUNDINGBOX (ENT / LL UR)
  (vla-getboundingbox (vlax-ename->vla-object ENT) 'LL 'UR)
  (mapcar 'vlax-safearray->list (list LL UR))
)

mccad

确实存在BUG，以下为VBA程序

2. Sub DB()
   
3.     Dim ent As AcadEntity
   
4.     Dim pnt As Variant
   
5.     ThisDrawing.Utility.GetEntity ent, pnt, vbCr & "选择对象："
   
6.     DrawBoundingBox ent
   
7. End Sub
   
8. 
   
9. 
   
10. Public Function DrawBoundingBox(ent As AcadEntity) As AcadLWPolyline
    
11.     Dim min, max
    
12.     ent.GetBoundingBox min, max
    
13.     Set DrawBoundingBox = Rectangle(min, max)
    
14. End Function
    
15. 
    
16. Public Function Rectangle(Point1, Point2) As AcadLWPolyline
    
17.     Dim vertices(0 To 7) As Double, pl As AcadLWPolyline
    
18.     vertices(0) = CDbl(Point1(0)): vertices(1) = CDbl(Point1(1))
    
19.     vertices(2) = CDbl(Point2(0)): vertices(3) = CDbl(Point1(1))
    
20.     vertices(4) = CDbl(Point2(0)): vertices(5) = CDbl(Point2(1))
    
21.     vertices(6) = CDbl(Point1(0)): vertices(7) = CDbl(Point2(1))
    
22.     Set pl = ThisDrawing.ModelSpace.AddLightWeightPolyline(vertices)
    
23.     pl.Closed = True
    
24.     Set Rectangle = pl
    
25. End Function
    

Sub DB()<br />     Dim ent As AcadEntity<br />     Dim pnt As Variant<br />     ThisDrawing.Utility.GetEntity ent, pnt, vbCr & "选择对象："<br />     DrawBoundingBox ent<br /> End Sub<br /> <br /> <br /> Public Function DrawBoundingBox(ent As AcadEntity) As AcadLWPolyline<br />     Dim min, max<br />     ent.GetBoundingBox min, max<br />     Set DrawBoundingBox = Rectangle(min, max)<br /> End Function<br /> <br /> Public Function Rectangle(Point1, Point2) As AcadLWPolyline<br />     Dim vertices(0 To 7) As Double, pl As AcadLWPolyline<br />     vertices(0) = CDbl(Point1(0)): vertices(1) = CDbl(Point1(1))<br />     vertices(2) = CDbl(Point2(0)): vertices(3) = CDbl(Point1(1))<br />     vertices(4) = CDbl(Point2(0)): vertices(5) = CDbl(Point2(1))<br />     vertices(6) = CDbl(Point1(0)): vertices(7) = CDbl(Point2(1))<br />     Set pl = ThisDrawing.ModelSpace.AddLightWeightPolyline(vertices)<br />     pl.Closed = True<br />     Set Rectangle = pl<br /> End Function<br />

绘出的图形：

congcong

这个函数返回的值针对同一个图形有时候是正确的，有时候又是错误的，有没有办法避免错误的情况出现。或者说能不能找到函数出现运行错误的规律

mccad

找规律是没办法，但看是否正确还是有办法，可以计算框与图元的交点数，对于封闭的样条线及拟合化的多段线，框与图元的交点应该有四个。

龙龙仔

2. 
   
3. ;;OFFSET 2次,一进一出,可以缩少误差,但不一定正确
   
4. (defun GETBOUNDINGBOX_LAI (ENT / LL UR EN1 EN2 TYP)
   
5.   (setq TYP (cdr (assoc 0 (entget ENT))))
   
6.   (if (and (/= TYP "XLINE") (/= TYP "RAY"))
   
7.     (if        (= "SPLINE" TYP)
   
8.       (progn
   
9.         (setq EN (vlax-ename->vla-object ENT))
   
10.         ;;可能会不能OFFSET
    
11.         ;;---------------------
    
12.         (vl-catch-all-apply
    
13.           'vla-offset
    
14.           (list EN 1)
    
15.           ;;OFFSET距离还在测试
    
16.         )
    
17.         (setq EN1 (entlast))
    
18.         (vl-catch-all-apply
    
19.           'vla-offset
    
20.           (list (vlax-ename->vla-object EN1) -1)
    
21.           ;;OFFSET距离还在测试
    
22.         )
    
23.         ;;--------------------------
    
24.         (entdel EN1)
    
25.         (setq EN2 (entlast))
    
26.         (vla-getboundingbox (vlax-ename->vla-object EN2) 'LL 'UR)
    
27.         (entdel EN2)
    
28.         (mapcar 'vlax-safearray->list (list LL UR))
    
29.       )
    
30.       (progn
    
31.         (vla-getboundingbox (vlax-ename->vla-object ENT) 'LL 'UR)
    
32.         (mapcar 'vlax-safearray->list (list LL UR))
    
33.       )
    
34.     )
    
35.   )
    
36. )
    
37. 
    
38. (defun C:TT (/ ENT BOX)
    
39.   (setvar "OSMODE" 0)
    
40.   (setq ENT (car (entsel)))
    
41.   (setq BOX (GETBOUNDINGBOX_LAI ENT))
    
42.   (vl-cmdf ".RECTANG" (car BOX) (cadr BOX))
    
43.   (princ)
    
44. )
    

<br /> ;;OFFSET 2次,一进一出,可以缩少误差,但不一定正确<br /> (defun GETBOUNDINGBOX_LAI (ENT / LL UR EN1 EN2 TYP)<br />   (setq TYP (cdr (assoc 0 (entget ENT))))<br />   (if (and (/= TYP "XLINE") (/= TYP "RAY"))<br />     (if        (= "SPLINE" TYP)<br />       (progn<br />         (setq EN (vlax-ename->vla-object ENT))<br />         ;;可能会不能OFFSET<br />         ;;---------------------<br />         (vl-catch-all-apply<br />           'vla-offset<br />           (list EN 1)<br />           ;;OFFSET距离还在测试<br />         )<br />         (setq EN1 (entlast))<br />         (vl-catch-all-apply<br />           'vla-offset<br />           (list (vlax-ename->vla-object EN1) -1)<br />           ;;OFFSET距离还在测试<br />         )<br />         ;;--------------------------<br />         (entdel EN1)<br />         (setq EN2 (entlast))<br />         (vla-getboundingbox (vlax-ename->vla-object EN2) 'LL 'UR)<br />         (entdel EN2)<br />         (mapcar 'vlax-safearray->list (list LL UR))<br />       )<br />       (progn<br />         (vla-getboundingbox (vlax-ename->vla-object ENT) 'LL 'UR)<br />         (mapcar 'vlax-safearray->list (list LL UR))<br />       )<br />     )<br />   )<br /> )<br /> <br /> (defun C:TT (/ ENT BOX)<br />   (setvar "OSMODE" 0)<br />   (setq ENT (car (entsel)))<br />   (setq BOX (GETBOUNDINGBOX_LAI ENT))<br />   (vl-cmdf ".RECTANG" (car BOX) (cadr BOX))<br />   (princ)<br /> )<br />

mccad

试过以上我绘的几个图形，
拟合过的多段线：还是那个框。
样条曲线：框小了，但还不是要求的框，看了一下，外框还把控制点给包含进来了。

无痕

offset有时候会得出好几段来，用entlast未必能得到想要的曲线