static public float atan2_fast(float y, float x) {
		// From: http://dspguru.com/comp.dsp/tricks/alg/fxdatan2.htm
		float abs_y = y < 0 ? -y : y;
		float angle;
		if (x >= 0)
			angle = 0.7853981633974483f - 0.7853981633974483f * (x - abs_y) / (x + abs_y);
		else
			angle = 2.356194490192345f - 0.7853981633974483f * (x + abs_y) / (abs_y - x);
		return y < 0 ? -angle : angle;
	}