Lindenmayer

// L-SYSTEMS: https://en.wikipedia.org/wiki/L-system

// takes the turtle we created in the last project and automates the drawing based on a Lindenmayer or L system

​

// (1) take a look at the L-system implemented here, and see if you can expand upon it to do some automatic, cool, geometric drawing

// hint: google L-systems and you can use non-drawing symbols as symbolic placeholders to create really complex patterns

​

// TURTLE STUFF:

var xx, yy; // the current position of the turtle

var rightnowanglee = 0; // which way the turtle is pointing

var distancee = 45; // how much the turtle moves with each 'f'

var anglee = 90; // how much the turtle turns with a '-' or '+'

​

// LINDENMAYER STUFF (L-SYSTEMS)

var stringg = 'A'; // "axiom" or start of the string

var rulee = []; // array for rules

rulee[0] = ['A', 'f+Af-']; // first rule

// rulee[1] = ['B', '']; // second rule

var amountt = 5; // how many iterations of the L-system to pre-compute

var rightnowstringg = 0; // where in the L-system are we drawing right now

​

function setup()

{

  createCanvas(750, 750);

  background(255);

  noStroke();

  frameRate(15);

  // start the xx and yy position at the center

  xx = 0;

  yy = 0;

  // COMPUTE THE L-SYSTEM

  for(var i = 0; i < amountt; i++) {

    stringg = lsystemm(stringg); // do the stuff to make the string

  }

}

​

function draw()

{

  // draw the current character in the string:

  draww(stringg.charAt(rightnowstringg)); 

  // increment the point for where we're reading the string

  // wrap around at the end

  rightnowstringg++;

  if(rightnowstringg>stringg.length-1) rightnowstringg = 0;

}

​

// interpret an L-system

function lsystemm(symboll)

{

  var blankstringg = ''; // start a blank output string

  // go through the string, doing rewriting as we go

  // iterate through 'rulee' looking for symbol matches:

  for(var i = 0; i < symboll.length; i++) // every symbol in 's'

  {

    var matchingg = 0; // by default which is no match

    for(var j = 0; j < rulee.length; j++) // every rule in 'rulee'

    {

      if(symboll.charAt(i)==rulee[j][0]) // MATCH!

      {

        blankstringg+=rulee[j][1]; // write substitution

        matchingg = 1; // we have a match, so do not copy over symbol

        break; // get out of the for() loop

      }

    }

    // if nothing matches in 'rulee' array, just copy the symbol over

    if(matchingg===0) blankstringg+= symboll.charAt(i); 

  }

  return(blankstringg); // send out the modified string

}

​

// a custom function that draws turtle commands

function draww(keyy)

{

  if(keyy=='f') // draw forward

  {

    // polar to cartesian transformation based on distance and current angle:

    var xx1 = xx + distancee*cos(radians(rightnowanglee));

    var yy1 = yy + distancee*sin(radians(rightnowanglee));

    // update the turtle's position:

    xx = xx1;

    yy = yy1;

  }

  else if(keyy=='+')

  {

   rightnowanglee+=anglee; // turn left

  }

  else if(keyy=='-')

  {

   rightnowanglee-=anglee; // turn right   

  }

  fill(random(255)); // interior fill color

  ellipse(xx, yy, 90, 90); // circle that chases the mouse

}