AutoCAD二次开发

一种是Autolisp语言开发的
还有一个就是利用vb开发的接口，称为activex Automation

以上两位的回答过于繁琐，让大师我给他们简略一下，取其精华．

这两个确实太麻烦了，简直是要把人弄晕，开始理解的化，可以是画个三角形什么的，编程，找本书看看就明白，几行而已

一种是Autolisp语言开发的，过时，不太好用。
还有一个就是利用vb开发的接口，称为activex Automation。是从1995年前后CAD才支持的，可以把CAD作为vb中的一个对象进行控制。只要你会使用vb,难度不是很大，此外还可以方便地定制自己的菜单等等。
买书的时候，书店老板是不会知道这些的。但是有些书中包括这部分的内容。打开目录了解一下就可。

我还是喜欢lisp，说过时？呵呵，那你问问天正软体是用什麽开发出来的。其实也挺简单的，举个例子的话，因为我是做建筑设计的，自已写了个z坐标一次归0的lisp：
(vmon) (defun c:zz (/ wholesel count treatcount chcount ent curent segcurent entlist segentlist etflag dfetflag input ) (command "_.undo" "_begin") (setq old_err *error* *error* zz_err ) (PRinc " ***********z坐标值归零程序***********作者 燕鹏动力******" ) (setvar "cmdecho" 0) (setq wholesel (ssget '((-4 . "") ) ) ) (if (null wholesel) (Progn (PRinc "\n未选择到有效实体!") (exit) ) ) (setq count 0) (setq treatcount 0) (setq chcount 0) (PRinc "\n") (while (< count (sslength wholesel)) (setq curent (ssname wholesel count)) (setq entlist (entget curent)) (setq count (1+ count)) (PRinc "\r已经完成 ") (PRinc (rtos (/ count (sslength wholesel) 0.01) 2 1)) (PRinc " %.") (PRinc) (if (or (/= (CADr (assoc 210 entlist)) 0.0) (/= (CADdr (assoc 210 entlist)) 0.0) (/= (CADddr (assoc 210 entlist)) 1.0) ) (Progn (if (null dfetflag) (Progn (setq dfetflag "n") (setq etflag dfetflag) (initget 0 "y n") (setq input (getkWord (strcat "\n***燕鹏动力友情提示***图中存在伸展方向非常规的实体,若不更改某些z值不能归零,是否强行更改(y/n) <" dfetflag ">:" ) ) ) (if input (setq etflag input) ) (setq dfetflag etflag) ) ) (if (= etflag "y") (Progn (setq entlist (SUbst (cons 210 '(0.0 0.0 1.0)) (assoc 210 entlist) entlist ) ) (entmod entlist) ) ) ) ) (cond ((= "point" (CDR (assoc 0 entlist))) (setq oldpt (CDR (assoc 10 entlist))) (if (/= (CADdr oldpt) 0.0) (Progn (setq treatcount (1+ treatcount)) (setq newpt (list (car oldpt) (CADr oldpt) 0.0)) (setq entlist (SUbst (cons 10 newpt) (cons 10 oldpt) entlist) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ((= "line" (CDR (assoc 0 entlist))) (setq oldbgpt (CDR (assoc 10 entlist))) (setq oldendpt (CDR (assoc 11 entlist))) (if (or (/= (CADdr oldbgpt) 0.0) (/= (CADdr oldendpt) 0.0)) (Progn (setq treatcount (1+ treatcount)) (setq newbgpt (list (car oldbgpt) (CADr oldbgpt) 0.0)) (setq newendpt (list (car oldendpt) (CADr oldendpt) 0.0)) (setq entlist (SUbst (cons 10 newbgpt) (cons 10 oldbgpt) entlist) ) (setq entlist (SUbst (cons 11 newendpt) (cons 11 oldendpt) entlist ) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ((= "lwpolyline" (CDR (assoc 0 entlist))) (if (/= (CDR (assoc 38 entlist)) 0.0) (Progn (setq treatcount (1+ treatcount)) (setq entlist (SUbst (cons 38 0.0) (assoc 38 entlist) entlist ) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ((= "polyline" (CDR (assoc 0 entlist))) (setq oldpt (CDR (assoc 10 entlist))) (if (/= (CADdr oldpt) 0.0) (Progn (setq treatcount (1+ treatcount)) (setq newpt (list (car oldpt) (CADr oldpt) 0.0)) (setq entlist (SUbst (cons 10 newpt) (cons 10 oldpt) entlist) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ((or (= "arc" (CDR (assoc 0 entlist))) (= "circle" (CDR (assoc 0 entlist))) ) (setq oldcenpt (CDR (assoc 10 entlist))) (if (/= (CADdr oldcenpt) 0.0) (Progn (setq treatcount (1+ treatcount)) (setq newcenpt (list (car oldcenpt) (CADr oldcenpt) 0.0)) (setq entlist (SUbst (cons 10 newcenpt) (cons 10 oldcenpt) entlist ) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ((= "text" (CDR (assoc 0 entlist))) (setq oldinspt (CDR (assoc 10 entlist))) (setq oldjustpt (CDR (assoc 11 entlist))) (if (or (/= (CADdr oldinspt) 0.0) (/= (CADdr oldjustpt) 0.0)) (Progn (setq treatcount (1+ treatcount)) (setq neWinspt (list (car oldinspt) (CADr oldinspt) 0.0) ) (setq newjustpt (list (car oldjustpt) (CADr oldjustpt) 0.0) ) (setq entlist (SUbst (cons 10 neWinspt) (cons 10 oldinspt) entlist ) ) (setq entlist (SUbst (cons 11 newjustpt) (cons 11 oldjustpt) entlist ) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ((= "insert" (CDR (assoc 0 entlist))) (setq oldinspt (CDR (assoc 10 entlist))) (if (/= (CADdr oldinspt) 0.0) (Progn (setq treatcount (1+ treatcount)) (setq neWinspt (list (car oldinspt) (CADr oldinspt) 0.0) ) (setq entlist (SUbst (cons 10 neWinspt) (cons 10 oldinspt) entlist ) ) (entmod entlist) (setq chcount (1+ chcount)) ) ) ) ) ) (PRinc (strcat "\n**燕鹏动力友情提示***共选中" (itoa count) "个有效实体, 其中z坐标值不归零的有" (itoa treatcount) "个实体，成功转换" (itoa chcount) "个实体:||作者 燕鹏动力||http://www.china-abbs.com||" ) ) (PRinc) (setq etflag nil) (setq dfetflag nil) (command "_.undo" "_end") ) (defun zz_err (s) (PRinc "\n命令中止!**燕鹏动力友情提示***http://www.china-abbs.com***") (setq etflag nil dfetflag nil ) (redraw) (setq *error* old_err) (PRinc) ) (PRinc)

可能这个格式写得看不清，再来一个：
数字匹量修改：
change elevations

;num.lsp
(defun c:num ()
(setq ss1 (ssget)
len1 (sslength ss1)
cnt 0
add (getreal "\nenter number to add to elevations: ")
)
(while (< cnt len1)
(setq dent (entget (ssname ss1 cnt))
txt (CDR (assoc 1 dent))
len (strlen txt)
cnt1 1
)
(while (<= cnt1 len)
(if (/= (SUbstr txt cnt1 1) " ")
(Progn
(setq num (atof (SUbstr txt cnt1 len))
numlen (strlen (rtos num 2 5)))
(if (/= num 0)
(Progn
(cond ((= (SUbstr txt cnt1 numlen) (rtos num 2 5)) (setq sp 0))
((= (SUbstr txt cnt1 (- numlen 1)) (rtos num 2 1)) (setq sp 1))
((= (SUbstr txt cnt1 (- numlen 3)) (rtos num 2 0)) (setq sp 3))
);cond
(setq rtxt (SUbstr txt (- (+ cnt1 numlen) sp) len)
num (+ add num)
numt (rtos num 2 5)
ntx (strcat (SUbstr txt 1 (- cnt1 1)) numt rtxt)
old (assoc 1 dent)
new (cons 1 ntx)
dent (SUbst new old dent)
cnt1 (+ 1 len)
);setq
(entmod dent)
);Progn
)));if,Progn,if
(setq cnt1 (1+ cnt1))
);end while
(setq cnt (1+ cnt))
);while
);defun

(dyPSoft前一部分的代码这么没层次感的?是不是lisp就是这样的?我真的连一行lisp也没见过的啊.谢谢了)
那到不是，最主要以前在广州的时候写的，后来直接用记事本文件把源码拷过来，然后就变成格式很乱的了，本人一向挺懒的，所以一直没改过来，就这样一直用了。呵呵。
第二段的很清楚明了，应该看得懂。