How to Create Lisp in AutoCAD

Understanding LISP in AutoCAD

LISP, short for "List Processing," is a powerful programming language that enables users to automate tasks within AutoCAD. It is particularly useful for creating custom routines that enhance productivity and simplify repetitive tasks.

Setting Up LISP in AutoCAD

To create and run LISP scripts in AutoCAD, follow these detailed steps:

Step 1: Prepare Your Environment

Before you start coding, ensure you have a compatible version of AutoCAD (such as AutoCAD 2025) that supports LISP routines. Familiarize yourself with the AutoCAD interface and verify that you have access to the command line.

Step 2: Create a New LISP File

1. Open a Text Editor: Use a simple text editor, such as Notepad or any code editor of your choice.

2. Write Your LISP Code: Start writing your LISP functions. A basic example to get you started might look like this:

   lisp
   (defun c:HelloCommand ()
   (princ "\nHello, AutoCAD!")
   )

3. Save the File: Save your script with a .lsp extension, for example, hello.lsp. Make sure to select "All Files" as the file type when saving to prevent it from saving as a text document.

Step 3: Load Your LISP File in AutoCAD

1. Open AutoCAD: Launch AutoCAD and open a drawing where you want to use your LISP routine.
2. Use the APPLOAD Command:
   • Type APLOAD in the command line and hit Enter.
   • In the dialog that appears, click on the "Contents" button under the Startup Suite.
   • Click the "Add" button and browse to the location of your LISP file. Select it and click "Open."
   • Once all necessary files are added, click "Close" to exit the dialog.

Running Your LISP Script

To execute your LISP routine, type the command name you defined in your LISP function at the command prompt. For instance, if your function is HelloCommand, simply type HelloCommand and hit Enter. You should see the message printed in the command line as specified in your code.

Creating More Complex LISP Programs

Using Built-In Functions

AutoLISP provides a plethora of built-in functions you can use to create more sophisticated scripts. Here’s how to implement loops and conditional statements:

1. Loops: Use foreach, while, or repeat to iterate over lists or perform actions multiple times.
2. Conditionals: Use if statements for decision-making in your routines.

Example:

lisp
(defun c:SumLayouts ()
(foreach layout (layoutlist)
(setvar ‘ctab layout)
(command "_.zoom" "_a" 1.0)
)
)

Automating Tasks

Automation is key when using LISP in AutoCAD. You can create scripts that handle tasks like:

• Batch processing layouts.
• Generating blocks or entities based on user-defined parameters.
• Customizing dimensions or annotations based on project specifications.

FAQs

1. Can I use LISP in AutoCAD LT?
No, AutoCAD LT does not support AutoLISP capabilities, and the APPLOAD command is not available on this version.

2. Where can I find LISP resources and libraries?
Various online resources and communities provide LISP libraries and example scripts. Websites such as forums and GitHub repositories are excellent places to look.

3. Is coding in LISP difficult?
While some programming knowledge helps, understanding LISP in AutoCAD is approachable. Logical thinking and familiarity with AutoCAD commands will aid in developing effective scripts.