//axiom: A

//rules: (A -> AB), (B -> A)

​

//variables: F+-[]

//axiom: F

//rules: FF+[+F-F-F]-[-F+F+F]

​

let angle;

let axiom = "F";

let sentence = axiom;

let len = 100;

​

let rules = [];

rules[0] = {

  a: "F",

  b: "FF+[+F-F-F]-[-F+F+F]"

};

​

​

function generate() {

  len *= 0.5;

  let nextSentence = "";

  for (let i = 0; i < sentence.length; i++) {

    let current = sentence.charAt(i);

    let found = false;

    for (let j = 0; j < rules.length; j++) {

​

      if (current == rules[j].a) {

        found = true;

        nextSentence += rules[j].b

        break;

      }

    }

    if (!found) {

      nextSentence += current;

    }

  }

  sentence = nextSentence;

  createP(sentence);

  turtle();

}

​

function turtle() {

  background(220);

  resetMatrix();

  translate(width/2, height);

  for (let i = 0; i < sentence.length; i++) {

        let current = sentence.charAt(i);

    if(current == "F"){

      stroke(0, 100);

      line(0,0,0,-len);

      translate(0, -len);

    }else if(current == "+"){

      rotate(angle);

    }else if(current == "-"){

      rotate(-angle);

    }else if(current == "["){

      push();

    }else if(current == "]"){

      pop();

    }

  }

}

​

function setup() {

  createCanvas(400, 400);

  angle = radians(25);

  background(220);

  createP(axiom);

  turtle();

  let button = createButton("generate");

  button.mousePressed(generate);

}

​

function draw() {

}