growing sea grass

var thestring = '';

var therules = [];

var numproductions, t, d;

​

// curves

thestring = 'F-F-F-F'; // the starting string ("axiom")

therules[0] = ['F', 'F-F+F+FF-F-F+F'];

//therules[0] = ['F', 'FF-F-F-F-FF'];

numproductions = 4;

t = 85; // turn amount

d = 6;

var ptr = 0;

​

​

// graphics stuff:

// a simple version of Papert's turtle

var x = [];

var y = [];

var a = [];

var lpf = 1; // letters per frame

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  init();

  // triple loop:

  var outstring = thestring;

  for(let i = 0;i<numproductions;i++)

  {

    outstring = '';

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

    {

      for(let k = 0;k<therules.length;k++)

      {

        var ismatch = 0;

        if(thestring.charAt(j)==therules[k][0]) // MATCH

        {

          outstring+=therules[k][1]; // copy of the second half

          ismatch=1;

          break;

        }

      }

      if(ismatch==0) outstring+=thestring.charAt(j);

    }

    thestring=outstring;

    console.log(thestring);

  }

    //console.log(thestring);

  //frameRate(12);

  strokeWeight(2);

  stroke(255)

}

​

function draw() {

  var c;

  for(let i = 0;i<lpf;i++)

  {

    c = thestring.charAt(ptr);

    if(ptr<thestring.length) doTurtle(c);

    ptr = ptr+1;

  }

}

​

function init() {

  background(0);

  x = [];

  y = [];

  a = [];

  x[0] = width/1.1;

  y[0] = height/1;

  a[0] = PI*4/3;

}

​

function doTurtle(k) {

  if(k=='c') init();

  if(k=='F') // draw forward

  {

    let x1 = x[x.length-1] + d*cos(a[a.length-1]);

    let y1 = y[y.length-1] + d*sin(a[a.length-1]);

    line(x[x.length-1], y[y.length-1], x1, y1);

    x[x.length-1] = x1;

    y[y.length-1] = y1;

  }

  if(k=='+') // turn right

  {

    stroke('green');

    a[a.length-1]+=radians(t);

  }

  if(k=='-') // turn left

  {

    stroke(255);

    a[a.length-1]-=radians(t);

  }

  if(k=='[') // start branch

  {

    x.push(x[x.length-1]);

    y.push(y[y.length-1]);

    a.push(a[a.length-1]);

  }

  if(k==']') // end branch

  {

    x.pop();

    y.pop();

    a.pop();

  }

}