var streams = [];

var fadeInterval = 1.4;

var symbolSize = 15;

​

function setup() {

  createCanvas(

    800,

   600

  );

  background(0);

​

  var x = 0;

  for (var i = 0; i <= width / symbolSize; i++) {

    var stream = new Stream();

    stream.generateSymbols(x, random(-2000, 0));

    streams.push(stream);

    x += symbolSize

  }

​

  textFont('Consolas');

  textSize(symbolSize);

}

​

function draw() {

  background(0, 150);

  streams.forEach(function(stream) {

    stream.render();

  });

}

​

function Symbol(x, y, speed, first, opacity) {

  this.x = x;

  this.y = y;

  this.value;

​

  this.speed = speed;

  this.first = first;

  this.opacity = opacity;

​

  this.switchInterval = round(random(2, 25));

​

  this.setToRandomSymbol = function() {

    var charType = round(random(0, 5));

    if (frameCount % this.switchInterval == 0) {

      if (charType > 1) {

        // set it to Katakana

        this.value = String.fromCharCode(

          0x30A0 + round(random(0, 96))

        );

      } else {

        // set it to numeric

        this.value = round(random(0,9));

      }

    }

  }

​

  this.rain = function() {

    this.y = (this.y >= height) ? 0 : this.y += this.speed;

  }

​

}

​

function Stream() {

  this.symbols = [];

  this.totalSymbols = round(random(5, 35));

  this.speed = random(5, 22);

​

  this.generateSymbols = function(x, y) {

    var opacity = 255;

    var first = round(random(0, 4)) == 1;

    for (var i =0; i <= this.totalSymbols; i++) {

      symbol = new Symbol(

        x,

        y,

        this.speed,

        first,

        opacity

      );

      symbol.setToRandomSymbol();

      this.symbols.push(symbol);

      opacity -= (255 / this.totalSymbols) / fadeInterval;

      y -= symbolSize;

      first = false;

    }

  }

​

  this.render = function() {

    this.symbols.forEach(function(symbol) {

      if (symbol.first) {

        fill(140, 255, 170, symbol.opacity);

      } else {

        fill(0, 255, 70, symbol.opacity);

      }

      text(symbol.value, symbol.x, symbol.y);

      symbol.rain();

      symbol.setToRandomSymbol();

    });

  }

}