Programming

A few years ago, we posted some info and sample code on how to create a table in AutoCAD using autolisp. That works OK, but what if you want to define a particular table style first? I ran across this post by Lee Ambrosius on creating a table style from scratch using autolisp.



Read more about Create a table style in AutoCAD using autolisp

If you have been around AutoCAD for a while and have done any Autolisp or VBA programming, you have probably run across a great Autolisp and VBA site with tutorials and code examples named AfraLisp. About 4 years ago, the Afralisp website, created by and formerly maintained by Kenny Ramage was taken over by David Watson, who also runs http://www.CadTutor.net.




David has just completed Afralisp v2.0, a total rework of the website. Everything has been reorganized, and the whole site has a fresh look. Stop by and take a look, and leave some feedback. Read more about Afralisp 2.0

I have been working with the Civil 3D 2010 API in visual lisp recently, and I thought I would share an example of working with an alignment object. This example has plenty of comments, but basically it shows you how to find a point near the alignment based on a station and offset. Then it does the opposite and shows you how to determine the station and offset, given a point. For clarity, I have left out most of the error checking. Read more about Accessing Civil 3D objects with autolisp

Ok, getting back to the last (ssget) call in part 1...

(ssget "_W" 
 (list 5.0 5.0)(list 8.0 8.0)
 '((0 . "CIRCLE")(-4 . "<")(40 . 1.0))
)

If you have written routines with Autolisp, then you have probably used the (ssget) function to select entities on the screen, either automatically or by prompting the user.

(ssget) is a powerful function that can do more than you probably realize. Let's look at a simple example.

(ssget '((0 . "TEXT")))
 Read more about Exploring the autolisp SSGET function - part 1

In the previous post about Startup Lisp Functions, the special (S::STARTUP) function was mentioned. Startup lisp code is loaded before the drawing is initialized, but you cannot call the (COMMAND) function until after the drawing is initialized. The solution is to place your (COMMAND) calls inside the (S::STARTUP) function. Read more about S::STARTUP Function

If you have lisp routines that you want to make available in each drawing session, forget the "Startup Suite" and load them using the "acaddoc.lsp" file. "acaddoc.lsp" is not included with AutoCAD, you create it yourself. But it is nothing more than a plain lisp file, except that the first one found at drawing startup (just put it in your support file search path), is loaded automatically each time a drawing is opened. Read more about Startup Lisp Functions

Here is a simple example of how to read a TXT file into lisp and then do something with the contents. In this example, the TXT file contains coordinates, and the code will draw either points or lines.

One thing to keep in mind. Most times when you open a file for read or write, you should open the file, perform the entire operation, then close the file. Keep the code to a minimum while the file is open. This way if you run into an unhandled error, the file isn't stuck open, and in the case of shared files, you are not locking the file for an extended amount if time. Read more about Reading a TXT file using LISP

If you program with autolisp, you have probably used the command function at some point, probably to construct drawing entities. There is certainly nothing wrong with that. However, if you are working on a large program that constructs a lot of drawing entities, you may have noticed that the command function runs pretty slow.

I put together some tests to compare the (command) function to two other methods of entity creation, (entmake) and (vla-add...). The test constructs 1,999 line entities using various methods.

Read more about Command vs. entmake vs. vla-add

Pages

 


All content is copyright © CAD PANACEA 2005-2013 unless otherwise noted and may not be reproduced. All comments posted to this blog are the sole responsibility of the person making the comment.

Google, as a third party vendor, uses cookies to serve ads on this site. Google's use of their cookies enables it to serve ads to users based on their visit to your sites and other sites on the Internet. You may opt out of the use of these cookies by visiting the Google ad and content network privacy policy.

Powered by Drupal