AutoLISP Tutorial 3: Intuitive Line Drawing Tool

Welcome to Tutorial 3! In our journey to mastering AutoCAD scripting with AutoLISP, it’s essential to understand how to create tools that simplify the drafting process. In this tutorial, we’ll dive into building a tool that makes drawing continuous lines intuitive and seamless. By the end of this lesson, you’ll have crafted a function that elevates the user’s experience by minimizing prompts and maximizing efficiency.


Your goal is to craft a custom AutoCAD function that simplifies the line drawing experience for users. This function should allow for continuous line drawing, with users only needing to specify points sequentially.

Task Overview:

  1. Commencement: Begin by establishing a function that will house all your commands.
  2. User Interaction: Your function should start by asking users to specify the initial point of the line.
  3. Continuous Drawing: After the initial point is set, your function should continue to ask for subsequent points. Each time a new point is provided, a line segment should be drawn connecting the last two points.
  4. End Sequence: If a user decides not to specify a new point (essentially skipping the action), the function should recognize this as an end signal for the drawing sequence.
  5. User Experience Enhancement: It’s always a great idea to minimize any potential distractions for the user while they interact with your function. Consider how you can refine the interface to make it as seamless as possible.
  6. Completion: Ensure that once all tasks are carried out and the user has finished their drawing, your function returns the environment back to its standard setting.


  • Make sure the function has a clear starting and stopping point.
  • It’s crucial to test your function multiple times with varying inputs to ensure that it behaves as expected.
  • Remember, clarity in user prompts enhances user experience significantly.

Detailed Solution: Intuitive Line Drawing Tool in AutoLISP


Understanding how to leverage AutoLISP for enhancing drawing functions in AutoCAD can greatly boost productivity. This solution will guide you through creating a tool that lets users draw continuous lines by specifying points, offering a seamless user experience.

The Program:

(defun drawline ( )
(setq svcm (getvar “cmdecho”))
(setvar “cmdecho” 0)
(setq pnt1 (getpoint “\Specify first point: “))
(if (not pnt1)
(setq stp1 1)
(setq stp1 0)
(while (= stp1 0)
(setq pnt2 (getpoint pnt1 “\nSpecify next point: “))
(if (not pnt2)
(setq stp1 1)
(command “LINE” pnt1 pnt2 “”)
(setq pnt1 pnt2)
(setvar “cmdecho” svcm)

Line by Line Explanation:

(defun drawline ( ): This line initiates our custom function named ‘drawline’ which takes no arguments.

(setq svcm (getvar “cmdecho”)): Here, we are storing the current value of the “cmdecho” system variable, so we can revert back to it at the end.

(setvar “cmdecho” 0): We’re temporarily setting the “cmdecho” variable to 0. This suppresses command echoes, giving users a cleaner interface.

(setq pnt1 (getpoint “\Specify first point: “)): Prompting the user to specify the first point for the line and storing it in pnt1.

(if (not pnt1)…: This section checks if the user did not specify a point. If they didn’t, it sets a stopping condition stp1 to 1. Otherwise, it’s set to 0.

(while (= stp1 0)…: A loop that continues drawing lines as long as the stopping condition stp1 remains 0.

(setq pnt2 (getpoint pnt1 “\nSpecify next point: “)): Inside the loop, the user is prompted to specify the next point, taking the previous point as reference.

(if (not pnt2)…: This checks if the user skips specifying a point. If skipped, the loop’s stopping condition is activated. If a point is provided, the line is drawn.

(setq pnt1 pnt2): The new point becomes the reference for the next loop iteration.

(setvar “cmdecho” svcm): This reverts the “cmdecho” variable back to its original state, ensuring we leave the environment as we found it.

(princ): A clean exit from our function, ensuring no stray values are printed in the command line.


Congratulations on completing Tutorial 3! By now, you should have a solid grasp on creating an interactive tool in AutoLISP. Remember, the key is to always prioritize the user’s experience, making their tasks as straightforward as possible. As you continue to explore AutoLISP, think of other ways you can streamline drafting processes, and don’t be afraid to get creative. Keep practicing, and soon you’ll be building even more advanced and useful tools for AutoCAD!