public void update(int deltaT) {

		if (transitioning) {

			float change = (float) deltaT / (float) SUNRISE_SET_LENGTH;

			if (isDay) {
				brightness -= change;
			} else {
				brightness += change;
			}

			if (timeSince < SUNRISE_SET_LENGTH) {
				timeSince += deltaT;
			} else {
				timeSince = 0;
				transitioning = false;
				isDay = !isDay;
			}

		} else {
			if (timeSince < LENGTH_OF_NIGHT_DAY) {
				timeSince += deltaT;
			} else {
				timeSince = 0;
				transitioning = true;
			}
		}
	}