3dsolid实体组成的块得到的最小包围框不对，怎么解决？

no13bus

3dsolid实体组成的块得到的最小包围框不对。总是有偏差。这个块是动态块。实际的结果应该是图片里面显示的那样。但是我得到的最小点和最大点总是和图上的有距离。
大致的代码如下

1. (if (= (vla-get-objectname (vlax-ename->vla-object (ssname ssents i)) "AcDbBlockReference"))
   
2.        (progn
   
3.      (vla-getboundingbox (vlax-ename->vla-object (car (entsel))) 'minpoint 'maxpoint)
   
4.     (setq minpt (vlax-safearray->list minpoint))
   
5.     (setq maxpt (vlax-safearray->list maxpoint))
   
6. ;;;  (getpoint minpt)   (getpoint maxpt)
   
7.     (setq chang (abs (- (car minpt) (car maxpt))))
   
8.           (setq gao (abs (- (cadr minpt) (cadr maxpt))))
   
9.           (setq hou (abs (- (caddr minpt) (caddr maxpt))))
   
10. 
    
11.    
    
12. 
    
13.    
    
14.        )
    
15.       )

(if (= (vla-get-objectname (vlax-ename->vla-object (ssname ssents i)) "AcDbBlockReference"))<br />        (progn<br />      (vla-getboundingbox (vlax-ename->vla-object (car (entsel))) 'minpoint 'maxpoint)<br />     (setq minpt (vlax-safearray->list minpoint))<br />     (setq maxpt (vlax-safearray->list maxpoint))<br /> ;;;  (getpoint minpt)   (getpoint maxpt)<br />     (setq chang (abs (- (car minpt) (car maxpt))))<br />           (setq gao (abs (- (cadr minpt) (cadr maxpt))))<br />           (setq hou (abs (- (caddr minpt) (caddr maxpt))))<br /> <br />    <br /> <br />     <br />        )<br />       )