The Inters Function Of AutoLISP 1

Introduction


Now I'm going to talk about the INTERS function of AutoLISP. You know what the INTERS function does. It finds the point where two line cross.


I can also find the find where the extension of tow lines cross. But then the use is a little bit different.


What The AutoLISP Program Does


The AutoLISP starts. Id there is something in the screen, then it is deleted. We start with an empty screen.


The AutoLISP program asks us to pick two points for the first line and two points for the second line. The lines are drawn.


Now two things can happen:


1. The lines cross
2. The lines don't cross


If the lines cross, then see what you will get in the AutoCAD screen. A donut is drawn in the point where the lines cross.


If the lines do not cross, then a donut is drawn where the extended lines cross. Look at the picture that I have got.


That is clear. No matter if the lines cross or don't cross. A donut is drawn where the lines cross or the extended lines cross.

The AutoLISP Program


Here is the AutoLISP program:


(defun c:inter (/ ls p1 p2 p3 p4)
(start)
(setq ls (drwln "\nFirst line")
p1 (car (nth 0 ls))
p2 (car (nth 1 ls))
)
(setq ls (drwln "\nSecond line")
p3 (car (nth 0 ls))
p4 (car (nth 1 ls))
)
(drwdn p1 p2 p3 p4)
(endpr)
)


(defun start (/ p1 p2 ss)
(setvar "cmdecho" 0)
(command "zoom" "all")
(setq p1 (getvar "vsmin")
p2 (getvar "vsmax")
ss (ssget "c" p1 p2)
)
(if ss
(command "erase" "all" "")
)
)


(defun drwln (tx / p1 p2)
(setq p1 (getpoint (strcat tx " - point 1: "))
p2 (getpoint (strcat tx " - point 2: "))
)
(command "line" p1 p2 "")
(list (list p1) (list p2))
)


(defun drwdn (p1 p2 p3 p4 / p5)
(setq p5 (inters p1 p2 p3 p4))
(if p5
(princ "\nThe lines cross")
(progn
(princ "\nThe lines don't cross")
(setq p5 (inters p1 p2 p3 p4 nil))
)
)
(command "donut" 0 0.5 p5 "")
)


(defun endpr ()
(setvar "cmdecho" 1)
(princ)
)


(c:inter)


Next Post


In the next post I'm going to talk about the functions of the AutoLISP program. I'm also going to explain how they work.

Telling Others Do you like what you have read? Do you know other people, that could be interested? Could you tell them about this blog?

Comment In the mean time. If you have any questions. Or you want to tell me something. Feel free to add a comment to this blog. I would love to hear from you. And when you come to me with a comment. I will give a reply to your question or remark.

Warning Don't spend a lot of money on AutoCAD Light. It is only for creating 2D drawings and it doesn't support AutoLISP. There is a very similar CAD program. And that is completely free. The name of the program? DraftSight. How to get it? Do a search on Google for “download DraftSight”. And you will find where you can download the program.

Only Create Drawings When your CAD operators don't create the borders of your drawings, a lot of time is saved. You get your drawings much faster. I have created a program that does exactly that. An AutoCAD drawing has been created and the program draws a border around it. If you want to see how the program works, go to YouTube. You'll find the working of the program here: http://www.youtu.be/O8Zy6n9zS8Q Now the AutoLISP program gives you the choice to select the size of your border. You can select A4, A3, A2, or A1. Maybe you already know the size of the border of your drawing. Maybe all your drawings have the size A1. If so. Let me know. That is important. The program finds the proper scale of your drawing. Or do you already know what the scale always is? I can write the AutoLISP program that you want. The price? I will only charge you RM 600.-. That is less than US $ 200.-.

You are welcome to publish my article provided you include the resource box with links intact.

Resource Box Jos van Doorn is an AutoLISP programmer and blogger. He is originally from Holland and now he lives in Malaysia. He is the founder of the Make AutoCAD Fast business. Make AutoCAD Fast is writing AutoLISP programs for AutoCAD users. Make AutoCAD Fast created an AutoLISP program for drawing a border around AutoCAD drawings. The program can be found on YouTube. http://www.youtu.be/O8Zy6n9zS8Q Jos is writing a blog. In it are AutoLISP programs with information and it is about Make AutoCAD Fast. You can find his blog here: http://www.makeautocadfast.blogspot.com Maybe you have a question. Or want to tell me something. You can contact me on this e-mail address: makeautocadfast@ymail.com

This article may be freely reprinted or distributed in its entirety in any Ezine, newsletter, blog, or website. As long as the following resource box is added: ------------------------------------------------- This article is written by Jos van Doorn. He is an AutoLISP programmer who has helped engineering firms and architects to get their AutoCAD drawings fast, without waiting for hours. You can find more valuable information about his business and AutoLISP at his blog. It is here: http://www.makeautocadfast.blogspot.com If you want to contact him. Go to his blog and leave a comment. -------------------------------------------------