let sentence = axiom;

let len = 100;

let angle;

​

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(51);

  stroke(255, 100);

  resetMatrix();

  translate(width / 2, height);

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

    let current = sentence.charAt(i);

    if (current == "F") {

      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);

  background(51);

  angle = radians(25);

  createP(axiom);

  let button = createButton("generate");

  button.mousePressed(generate);

  turtle();

}

​

​

​