l-systems & whimsy

elisse chow | november 16, 2023 — december 13, 2023

to my sister Janine, who taught me so much about the beauty of math growing up—thank you


While it's been incredibly difficult at times, I'm extremely proud of what I've created. In all honesty, I went into this project a little discouraged by my previous attempt of working with Lindenmayer Systems in the sequencer project, but I wanted another shot at it, and I'm glad I took it on.

To give a rundown of the project, its centered entirely on Lindenmayer Systems—a parallel rewriting system created by biologist Aristid Lindenmayer. My system follow traditional TurtleBot dynamics to draw out the visuals, and I've also mapped out a sonification system that similarly translates text audio. I don't think I can explain it better than what the Wikipedia page on L-systems says, so I'll copy over what they have to say and also give an example that they have:

"An L-system consists of an alphabet of symbols that can be used to make strings, a collection of production rules that expand each symbol into some larger string of symbols, an initial "axiom" string from which to begin construction, and a mechanism for translating the generated strings into geometric structures." — L-Systems Wikipedia page

There's a lot more on that page, but we should be good with this to begin. I do recommend taking a read through of that page! It's really cool to see what types of fractals and/or biological growth can be described using a system like this :D.

Before we finally get into the video, I'm not entirely sure why I chose the name "l-systems & whimsy". I think I maybe find the creation tool a bit whimsical and the real-time aspect quite fun. A disclaimer: I have found it crashes sometimes with segmentation faults unfortunately, so be careful with the Barnsley fern preset. Please enjoy designing with math!

instructions

download files here!

run with lsystems_and_whimsy.ck.

platform: MacOS This is a long gui, so I'll break it down as best as I can.

1. LSystems Generator
1. Axiom: Text input box where you can define the "axiom" of the l-system. This is the starting point and will be the definition for generation 0.
2. Alphabet: Text input box where you can define your alphabet of characters that you want to map the processing behavior for. Will filter out duplicate letters if applicable.
2. Rule Editing
1. Currently editing: Dropdown selection, where you can select one of the letters defined in the Alphabet text input to edit their rules.
2. String replace: Text input, the rule used by the central lsystem to replace the character with a longer string of other characters.
3. Drawing Rule: Dropdown selection (forward, left, right, push, pop, move, none), determines how the TurtleBot will react to the character that was just seen. See the bullets bellow for info on what each of these rules mean.
• forward | F/G: Moves the Turtlebot forward and draws a line
• left | +: Rotates the Turtlebot left by a set angle
• right | -: Rotates the Turtlebot right by a set angle
• push | [: Saves the current state to a stack
• pop | ]: Pops off the most recently saved state from the stack
• move (usually lowercase): Moves the Turtlebot forward without drawing a line
4. Audio Rule: Dropdown selection (play, increment, decrement, louder, softer, speed up, slow down, random preset, change instrument, none), determines how the sonification system will react to the character that was just seen.
5. Reset rules: Button, resets the rules for the standard characters in the alphabet.
3. Generation Settings
1. Angle: float slider, determines the angle that the turtlebot turns with every "+"/"-"
2. Set generation: int slider, set the number of the current generation that you would like to visualize.
3. Stepduration: int slider, set the time (ms) it takes for each step in the animation.
4. Begin: button, begins the animation & audio over time. Will restart if pressed again.
5. Replace: button, begins a new animation of currently setup l-system without erasing the previous lines that have already been drawn.
6. Stop: button, stops the animation/audio.
4. Presets: Each of these buttons preloads the system with a working l-system. Unfortunatley, the barnsley fern is a little buggy T^T.
5. Experimental
1. Show Turtlebot Toggle: Shows/hides the turtlebot sphere shown at the most recent point added to the visual.
2. Follow Cam Toggle: Switches the camera perspective between the top view and a 1st person view following the turtlebot drawing.

a final reflection

I am incredibly thankful—for this class because it has been so wonderful, for CCRMA for existing, for everyone because you have all been extremely supportive and uplifting. I don't think I've ever had a class that I've felt so much love for at Stanford before, and I doubt that I'll find anything like this in my last two quarters to come. Take care everyone, it's been such an honor to work with you this quarter. — elisse <333


Milestones