Unity shader 随机数

inline float ValueNoise(float3 pos)
{
     float3 Noise_skew = pos + 0.2127 + pos.x * pos.y * pos.z * 0.3713;
     float3 Noise_rnd = 4.789 * sin(489.123 * (Noise_skew));
     return frac(Noise_rnd.x * Noise_rnd.y * Noise_rnd.z * (1.0 + Noise_skew.x));
 }
...
float random (float2 st, float n) {
 	st = floor(st * n);
    return frac(sin(dot(st.xy, float2(12.9898,78.233)))*43758.5453123);
}
...
col = random(i.uv.xy, 10);
retunr col;