Writing a LISP program in AutoCAD can greatly enhance your productivity and automate repetitive tasks. LISP (List Processing Language) is a powerful programming language that allows you to extend the capabilities of AutoCAD beyond what is possible with the built-in commands and functions. In this tutorial, we will explore the process of writing a LISP program in AutoCAD.
Getting Started with LISP Programming in AutoCAD
If you are new to programming or LISP, don’t worry! AutoCAD provides an integrated development environment called the Visual LISP Editor where you can write, edit, and debug your LISP programs.
To open the Visual LISP Editor, simply type “VLIDE” in the command line and hit Enter. This will open up a new window where you can start writing your LISP code.
Understanding the Basics of LISP Syntax
Before we dive into writing our first LISP program, let’s familiarize ourselves with some basic syntax rules. In LISP, each command or function call is enclosed within parentheses. For example, to draw a line in AutoCAD using LISP, we would use the following syntax:
(command “line” point1 point2)
In this example, “command” is a built-in function in AutoCAD that allows us to execute a specific command (in this case, “line”). The points point1 and point2 represent the start and end coordinates of the line.
Note: It’s important to enclose strings within double quotes (“”) in LISP.
Create Your First LISP Program
Now that we understand the basics of LISP syntax, let’s create our first program that draws a rectangle with specified dimensions. Open up the Visual LISP Editor and follow along.
Step 1: Start by defining a new function using the defun keyword. This will allow us to call our program by its name later on. Let’s name our function “draw-rectangle”.
(defun draw-rectangle ()
Step 2: Inside the function, use the (command) function to execute AutoCAD commands. In this case, we want to draw a rectangle, so we’ll use the “rectang” command.
- (command “rectang”)
Note: You can find a list of available AutoCAD commands and their syntax in the AutoCAD documentation.
Step 3: Specify the dimensions of the rectangle using two points – the lower-left corner and upper-right corner. We’ll use arbitrary values for this example.
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(setq corner1 ‘(0 0)) ; Lower-left corner
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(setq corner2 ‘(10 10)) ; Upper-right corner
Step 4: Finally, pass these points as arguments to the “rectang” command.
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(command “rectang” corner1 corner2)
Step 5: Close the function definition with a closing parenthesis.
) ; End of draw-rectangle function
Testing Your LISP Program
To test your LISP program, save it with a “.lsp” extension. Then, load it into AutoCAD using the “APPLOAD” command and type in the name of your LISP file. Once loaded, you can execute your program by simply typing its name in the command line.
For example, if you named your program “draw-rectangle”, you would type (draw-rectangle) and hit Enter. AutoCAD will then execute the program and draw a rectangle with the specified dimensions.
Conclusion
Congratulations! You’ve successfully written your first LISP program in AutoCAD.
As you continue to explore LISP programming, you’ll discover endless possibilities for automating tasks, creating custom commands, and enhancing your productivity in AutoCAD. Remember to experiment, practice regularly, and refer to the AutoCAD documentation for more advanced concepts and functions.
Note: It’s important to regularly save your work and create backups of your LISP programs to avoid losing any progress.