在cad中直接画箭头

在中CAD中直接画箭头的命令的一个方法！！！
众所周知，在天正中可直接绘制箭头，而在AutoCAD中不得。最近我发现一个在命令行直接输入命令就可画出你想要的尺寸的箭头的方法，具体实施如下：
1、首先拷贝下列lisp程序，用ar为名以记事本格式保存，然后改后缀名为.lsp，作为一个lisp程序文件；程序如下：

(defun ureal (bit kwd msg def / inp)
(if def
(setq msg (strcat "\n" msg "<" (rtos def) ">: ")
bit (* 2 (fix (/ bit 2)))
)
(if (= " " (substr msg (strlen msg) 1))
(setq msg (strcat "\n" (substr msg 1 (1- (strlen msg))) ": "))
(setq msg (strcat "\n" msg ": "))
)
)
(initget bit kwd)
(setq inp (getreal msg))
(if inp inp def)
)

(defun upoint (bit kwd msg def bpt / inp)
(if def
(setq pts (strcat
(rtos (car def))
","
(rtos (cadr def))
(if
(and (caddr def) (= 0 (getvar "FLATLAND")))
(strcat "," (rtos (caddr def)))
""
)
)
msg (strcat "\n" msg "<" pts ">: ")
bit (* 2 (fix (/ bit 2)))
)
(if (= " " (substr msg (strlen msg) 1))
(setq msg (strcat "\n" (substr msg 1 (1- (strlen msg))) ": "))
(setq msg (strcat "\n" msg ": "))
)
)
(initget bit kwd)
(setq inp
(if bpt
(getpoint msg bpt)
(getpoint msg)
)
)
(if inp inp def)
)
(setq cm(getvar "cmdecho"))
(setvar "cmdecho" 0)

(defun C:AR ( / #dwgsc w v pt1 pt2 pt3 )
(if(= arscl nil)(setq arscl 0.1875))
(setq #dwgsc(getvar "DIMSCALE")
W(getvar "PLINEWID")
V(getvar "OSMODE")
L(getvar "CLAYER"))
(setq arscl(ureal 7 "" "请输入箭头长度" arscl))
(setvar "OSMODE" 1)
(setq pt1 (upoint 1 "" "指定箭头顶点" nil nil))
(setvar "OSMODE" 512)

(setq PT(entsel "\n选择直线上要画箭头一端的任意一点"))
(setq PT2(cadr PT))
(setq ED(entget(car PT)))
(setq PT3 (polar PT1 (angle PT1 PT2) (* #dwgsc arscl)))
(command "PLINE" pt1 "w" "0" (* #dwgsc (/ arscl 3)) pt3 "")
(setvar "OSMODE" V)
(setvar "CLAYER" L)
(setvar "plinewid" W)
(princ)
)
(setvar "cmdecho" cm)
(princ)


2、将ar.lsp拷贝至CAD目录下的support目录下；
3、在CAD目录下的support目录内找到文件acad2000doc.lsp文件（CAD2002下，在别的版本CAD中可能不是这个名，这是CAD的自动加载文件）；
4、用记事本程度打开acad2000doc.lsp文件，加入一行：(load "ar.lsp")
（注意字符要为英文字符）
5、保存后，重新启动CAD，在命令行就可输入ar命令直接画箭头了。