Processing and Arduino

I ripped this from an Arduino example. It's very basic but works quite well. Download the lates Arduino software, download the latest Processing Arduino class and add an Arduino board with one LED at pin 13.
For Paco!

import processing.serial.*;

import cc.arduino.*;

Arduino arduino;

color off = color(4, 79, 111);
color on = color(84, 145, 158);

int[] values = { Arduino.LOW, Arduino.LOW, Arduino.LOW, Arduino.LOW,
 Arduino.LOW, Arduino.LOW, Arduino.LOW, Arduino.LOW, Arduino.LOW,
 Arduino.LOW, Arduino.LOW, Arduino.LOW, Arduino.LOW, Arduino.LOW };

void setup() {
  size(470, 200);

  println(Arduino.list());
  arduino = new Arduino(this, Arduino.list()[1]);
  
  for (int i = 0; i <= 13; i++) {
    arduino.pinMode(i, Arduino.OUTPUT);
  }
}

void draw() {
  background(off);
  stroke(on);
  
  for (int i = 0; i <= 13; i++) {
    if (values[i] == Arduino.HIGH)
      fill(on);
    else
      fill(off);
      
    rect(420 - i * 30, 30, 20, 20);
  }
}

void mousePressed()
{
  int pin = (450 - mouseX) / 30;
  println(pin);
  if (values[pin] == Arduino.LOW) {
    arduino.digitalWrite(pin, Arduino.HIGH);
    values[pin] = Arduino.HIGH;
  } else {
    arduino.digitalWrite(pin, Arduino.LOW);
    values[pin] = Arduino.LOW;
  }
}