判断一个点是否在直线上或在直线的延长线上

lgx9612

判断一个点是否在直线上或在直线的延长线上（附:直线跟点都是给定参数而定的，图中并没有这此图素，是虚拟的，此程序用来计算用）

2. (defun inters_point&line (l-point1 l-point2 p-point1 show / return_result_lgx)
   
3. ;;;原创,编写:刘国新
   
4. ;;;判断一个点是否在直线上或在直线的延长线上
   
5. ;;;用法如下
   
6. ;;;(inters_point&line (getpoint "\n直线的第一点:\n")(getpoint "\n直线的第二点:\n")(getpoint "\n判断点是否落在直线上:\n") "show")
   
7. (setq return_result_lgx nil)  
   
8. (if (or (= l-point1 nil) (= l-point2 nil) (= p-point1 nil) (= (distance l-point1 l-point2) 0))
   
9. (setq return_result_lgx nil)
   
10. (progn
    
11. (if (or (equal (angle l-point1 l-point2)(angle l-point1 p-point1) 0.0005)(equal (angle l-point1 l-point2)(angle l-point2 p-point1) 0.0005))
    
12. (progn
    
13. (if (= (+ (distance p-point1 l-point1)(distance p-point1 l-point2))(distance l-point2 l-point1))
    
14. (progn
    
15. (if (/= show nil)
    
16. (princ "\n该点落在直线上!!!\n")
    
17. )
    
18. (setq return_result_lgx 1)
    
19. )
    
20. (progn
    
21. (if (/= show nil)
    
22. (princ "\n该点在直线的延长线上!!!\n")
    
23. )
    
24. (setq return_result_lgx 2)
    
25. )
    
26. )
    
27. )
    
28. (progn
    
29. (if (/= show nil)
    
30. (princ "\n该点不在直线上或直线的延长线上!!!\n")
    
31. )
    
32. (setq return_result_lgx nil)
    
33. )
    
34. )
    
35. )
    
36. )
    
37. (princ)
    
38. return_result_lgx
    
39. )

(defun inters_point&line (l-point1 l-point2 p-point1 show / return_result_lgx)<br /> ;;;原创,编写:刘国新<br /> ;;;判断一个点是否在直线上或在直线的延长线上<br /> ;;;用法如下<br /> ;;;(inters_point&line (getpoint "\n直线的第一点:\n")(getpoint "\n直线的第二点:\n")(getpoint "\n判断点是否落在直线上:\n") "show")<br /> (setq return_result_lgx nil)  <br /> (if (or (= l-point1 nil) (= l-point2 nil) (= p-point1 nil) (= (distance l-point1 l-point2) 0))<br /> (setq return_result_lgx nil)<br /> (progn<br /> (if (or (equal (angle l-point1 l-point2)(angle l-point1 p-point1) 0.0005)(equal (angle l-point1 l-point2)(angle l-point2 p-point1) 0.0005))<br /> (progn<br /> (if (= (+ (distance p-point1 l-point1)(distance p-point1 l-point2))(distance l-point2 l-point1))<br /> (progn<br /> (if (/= show nil)<br /> (princ "\n该点落在直线上!!!\n")<br /> )<br /> (setq return_result_lgx 1)<br /> )<br /> (progn<br /> (if (/= show nil)<br /> (princ "\n该点在直线的延长线上!!!\n")<br /> )<br /> (setq return_result_lgx 2)<br /> )<br /> )<br /> )<br /> (progn<br /> (if (/= show nil)<br /> (princ "\n该点不在直线上或直线的延长线上!!!\n")<br /> )<br /> (setq return_result_lgx nil)<br /> )<br /> )<br /> )<br /> )<br /> (princ)<br /> return_result_lgx<br /> )

st788796

(trans (mapcar '- pnt p1) 0 (mapcar '- p2 p1))
看 高飞版主那个 Trans 帖子

lgx9612

st788796 发表于 2014-8-29 23:57
(trans (mapcar '- pnt p1) 0 (mapcar '- p2 p1))
看 高飞版主那个 Trans 帖子

给个链接

st788796

lgx9612 发表于 2014-8-30 13:32
给个链接

这个 Trans  包含很多有用信息

1. ;;0 --- p1
   
2. ;;1 --- between p1 p1
   
3. ;;2 --- p2
   
4. ;;3 --- p2->p1 extend line
   
5. ;;4 --- p1->p2 extend lien
   
6. (defun p&ln (p p1 p2 / l d _x)
   
7.   (setq        l (trans (mapcar '- p p1) 0 (mapcar '- p2 p1))
   
8.         d (distance p1 p2)
   
9.   )
   
10.   (if (equal (setq _x (car l)) 0.0 1e-6)
    
11.     (progn (setq _x (last l))
    
12.            (cond
    
13.              ((equal _x 0.0 1e-6) 0)
    
14.              ((< 0 _x d) 1)
    
15.              ((equal _x d 1e-6) 2)
    
16.              ((< _x 0) 3)
    
17.              (t 4)
    
18.            )
    
19.     )
    
20.     _x
    
21.   )
    
22. )

;;0 --- p1<br /> ;;1 --- between p1 p1<br /> ;;2 --- p2<br /> ;;3 --- p2->p1 extend line<br /> ;;4 --- p1->p2 extend lien<br /> (defun p&ln (p p1 p2 / l d _x)<br />   (setq        l (trans (mapcar '- p p1) 0 (mapcar '- p2 p1))<br />         d (distance p1 p2)<br />   )<br />   (if (equal (setq _x (car l)) 0.0 1e-6)<br />     (progn (setq _x (last l))<br />            (cond<br />              ((equal _x 0.0 1e-6) 0)<br />              ((< 0 _x d) 1)<br />              ((equal _x d 1e-6) 2)<br />              ((< _x 0) 3)<br />              (t 4)<br />            )<br />     )<br />     _x<br />   )<br /> )

lgx9612

st788796 发表于 2014-8-30 13:52
这个 Trans  包含很多有用信息

受教，谢谢!非常巧妙,开始还不大好理解.受益非浅!

xvjiex

感谢楼主分享判断一个点是否在直线上或在直线的延长线上！

hh_lj007

感谢分享源码与讨论，受益匪浅！