create an elementary cellular automaton GIF

//_1DCA_save_GIF by fbz written in Processing
//generates an elementary cellular automata and saves it as an animated gif
//get the gifAnimation processing library at http://extrapixel.github.io/gif-animation/
import gifAnimation.*;

GifMaker gifExport;
int[] rules = { 0, 1, 1, 0, 1, 1, 1, 0 };
int gen = 1; // Generation
color on = color(255);
color off = color(0);

void setup() {
  size(61, 680); //width and length of the gif
  background(0);
  set(width-1, 0, on); //set the next to last pixel to white
  set(23, 0, on); //turn some more pixels on for the seed row
  set(42, 0, on);
  //set(7, 0, on);
  //set(38, 0, on);
  //set(28, 0, on);
  //set(46, 0, on);
  frameRate(15);
  gifExport = new GifMaker(this, "rule110_1.gif");
  gifExport.setRepeat(0);             // make it an "endless" animation
  gifExport.setTransparent(255, 255, 255); //make white transparent
  gifExport.setDelay(1000/15); //divide by the frameRate
}

void draw() {
// For each pixel, determine new state by examining current
// state and neighbor states and ignore edges that have only
// one neighbor
  for (int i = 1; i < width - 1; i++) {
    int left = get(i - 1, gen - 1); // Left neighbor
    int me = get(i, gen - 1); // Current pixel
    int right = get(i + 1, gen - 1); // Right neighbor
    if (rules(left, me, right) == 1) {
      set(i, gen, on);
    }
  }
  gifExport.addFrame(); //add a new frame to the gif
  gen++; // Increment the generation by 1
  if (gen > height - 1) { // If it reached the bottom of the screen,
    noLoop(); // stop the program
    gifExport.finish(); //write gif file to sketch folder
  }
}
// Implement the rules
int rules(color a, color b, color c) {
  if ((a == on) && (b == on) && (c == on)) {
    return rules[0];
  }
  if ((a == on) && (b == on) && (c == off)) {
    return rules[1];
  }
  if ((a == on) && (b == off) && (c == on)) {
    return rules[2];
  }
  if ((a == on) && (b == off) && (c == off)) {
    return rules[3];
  }
  if ((a == off) && (b == on) && (c == on)) {
    return rules[4];
  }
  if ((a == off) && (b == on) && (c == off)) {
    return rules[5];
  }
  if ((a == off) && (b == off) && (c == on)) {
    return rules[6];
  }
  if ((a == off) && (b == off) && (c == off)) {
    return rules[7];
  }
  return 0;
}