Lystem

Lystem is cross platform command line application to render L-System interpreted as turtle instructins. The program renders a series of images, one for each instruction (or more). It does not directly make a video, for that you can use something like ffmpeg with:

ffmpeg -r 60 -i images/out%d.png output.mp4

The LSystem generator is made to occupy as little memory as possible, so it can run on limited devices too.

Contributions are welcome and at the start of src/main.rs you can find a TODO list.

Usage

You can build the project with cargo

cargo run --release -- [ARGS]

There are two required parameters, the input configuration, and the number of generations to simulate

cargo run --release -- configs/maze.yml 3

This will render the images of the 3rd generation of maze.yml, interpreted by the turtle as specified in the file.

Optional parameters are:

• -l which sets the program to only render the last frame (when all the turtle instruction have been executed)
• -s which sets how many turtle instructions should be executed in each frame (translates to the playback speed, there more instruction you interpret per frame, the faster the video will be)

Configuration files

The L-System axiom and rules, along with the instructions to interpret the characters as turtle commands are written in yaml files. You can find many examples in the configs directory.

axiom: F+F+F+F

start_state:
  'color_r': 255
  'color_b': 255
  'step': 1
  'turning_angle': 90

rules:
  'F': FF+F+F+F+FF

commands:
  'F':
    - forward
    - add color_r -1
  '+':
    - clockwise

• axiom indicates the system axiom, each character is interpreted as a single symbol, only ASCII character are supported

• start_state describes the turtle initial state, there are many variables accessible:

  • color_r, color_g, color_b to indicate the r,g,b values of the turtle drawing color, from 0 to 255
  • step which sets how far the turtle travels each time it goes forward
  • turning_angle turning angle of the turle used by the clockwise and counterclockwise commands
  • rotation the initial rotation of the turtle

• rules tells how each symbol evolves

• commands says how to interpret the symbol as a turtle command

  • forward makes the turtle go foward by step
  • clockwise/counterclockwise makes the turtle turn clockwise/counterclockwise by turning_angle
  • push_stack pushed the current turtle state on the stack
  • pop_stack pops the stack on the current turtle state
  • add/multiply/set are functions which take two arguments, the variable to change and the value to apply. A variable can also be used as a value: add turning_angle step adds the value of step to the turning_angle. An integer can also handle operations with a decimal number (multiply color_r 1.5), being rounded toward -infinity after the calculations.

Lystem in action