public static float InverseSqrt(float f)
 {
     return((float)1.0f / MathF.Sqrt(f));
 }
        public static float SmoothStep(float edge0, float edge1, float x)
        {
            float tmp = MathF.Clamp((x - edge0) / (edge1 - edge0), 0.0f, 1.0f);

            return(tmp * tmp * (3.0f - 2.0f * tmp));
        }