var fade = 1.6;

var hl;

var streams = [];

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  textSize(letterSize);

  textFont('Consolas');

  hl = height + letterSize;

  for (let i = 0; i < width / letterSize; i++) {

    streams.push(new Stream());

    streams[i].generate(letterSize * i);

  }

}

​

function draw() {

  background(0, 150);

​

  streams.forEach(function(stream) {

    stream.display();

  });

}

​

class Letter {

  constructor(x, y, speed, opacity) {

    this.x = x;

    this.y = y;

    this.value = '';

    this.speed = speed;

    this.interval = round(random(5, 20));

    this.first = false;

    this.opacity = opacity;

  }

​

  change() {

    if (frameCount % this.interval == 0)

      this.value = String.fromCharCode(

        0x30A0 + round(random(0, 96))

      );

  }

​

  step() {

    this.y += this.speed;

    this.y = this.y % hl;

    this.change();

    this.display();

  }

​

  display() {

    if (this.first) 

      fill(180, 255, 180, this.opacity);

    else

      fill(0, 255, 70, this.opacity);

    text(this.value, this.x, this.y);

  }

}

​

class Stream {

  constructor() {

    this.stream = [];

    this.n = round(random(5, 30));

    this.speed = random(1, 5);

  }

​

  generate(x) {

    let y = random(-1000, 0);

    let opacity = 255;

    let opDec = (255 / (width / this.n))  / fade;

    for (let i = 0; i < this.n; i++) {

      this.stream.push(new Letter(x, y, this.speed, opacity))

      y -= letterSize;

      opacity -= opDec;

    }

    this.stream[0].first = true & !round(random());

  }

​

  display() {

    this.stream.forEach(function(letter) {

      letter.step();

    });

  }

}