dkruchinin/lsystem

L-system fractal generator

lsystem

Simple L-system based fractal generator written just for fun.

Usage

% ./lsystem.py
USAGE: ./lsystem.py -c <config.json> -g <WIDTH>x<HEIGHT> [-h]

• -g: controls geometry of a window where fractal will be drawn
• -c: specifies a file in JSON format with a description of fractal according to the L-system rules

L-system file syntax

{
	"iters": integer, // number of iterations
	"angle": double, // angle (in degrees from 0 to 360)
	"axiom": string,
	"rules": { // rules of inference
		string: string, // rule 1
		...,
		string: string // rule N
	}
}

Alphabet that can be used in axioms and rules is pretty simple: FGf+-[]. Each letter is responsible for particular turtle (see turtle graphics for more info) command, namely:

• F and G: draw forward
• f: move cursor forward without drawing anything
• +: turn right
• -: turn left
• [: push current state of the cursor into the stack
• ]: pop state of the cursor from the stack

Some examples of valid L-system files:

• Dragon curve

{
	"iters": 10,
	"angle": 90,
	"axiom": "F",
	"rules": {
		"F": "F+G+",
		"G": "-F-G"
	}
}

• Fractal plant

{
	"iters": 4,
	"angle": 22.5,
	"axiom": "F",
	"rules": {
		"F": "FF-[-F+F+F]+[+F-F-F]"
	}
}