//rules for generation of Dragon Curve

  {

    in: "X",

    out: "X+YF+"

  },

  {

    in: "Y",

    out: "-FX-Y"

  }

]

​

let iteration = 0;

​

function iterateSystem(system) {

  iteration += 1;

  let newSystem = "";

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

    //current char

    let char = system.charAt(i);

    //test each rule

    for (let rule of rules) {

      if (char == rule.in) {

        char = rule.out;

      }

    }

    //add to newSystem

    newSystem += char;

    // print("working...");

  }

​

  return newSystem;

}

​

function drawSystem(system) {

  let len = width / 4 * pow(0.75, iteration);

​

  len *= 0.5;

  let angle = radians(90);

​

  background(0, 0, 0);

  translate(width / 2, height / 2);

  stroke(255);

  colorMode(HSB);

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

    stroke(360*(i/system.length), 100, 100);

    let char = system.charAt(i);

​

    if (char === "F") {

      line(0, 0, 0, -len);

      translate(0, -len);

    } else if (char === "+") {

      rotate(angle);

    } else if (char === "-") {

      rotate(-angle);

    } else if (char === "[") {

      push();

    } else if (char === "]") {

      pop();

    } else if (char === "|") {

      rotate(radians(180));

    }

  }

}

​