code: public static float wrapAngleAroundZero (float a) {
  		if (a >= 0) {
  			float rotation = a % MathUtils.PI2;
  			if (rotation > MathUtils.PI) rotation -= MathUtils.PI2;
  			return rotation;
  		} else {
  			float rotation = -a % MathUtils.PI2;
  			if (rotation > MathUtils.PI) rotation -= MathUtils.PI2;
  			return -rotation;
  		}
  	}
docs: Wraps the given angle to the range [-PI, PI]
  @param a the angle in radians
  @return the given angle wrapped to the range [-PI, PI]