Grain from My top 3 design “Kisses” I like to add to every app

Grain.metal

#include <metal_stdlib>
using namespace metal;

[[ stitchable ]] half4 grain(float2 position, half4 color, float amount, float time) {
    float noise = fract(sin(dot(floor(position), float2(12.9898, 78.233)) + time) * 43758.5453);
    return half4(color.rgb + half3((noise - 0.5) * amount), color.a);
}