GLSL value noise with

value-noise-with-lut.frag

uniform sampler2D s_noise;

float pn( in vec3 p ) {
  vec3 i = floor(p); p -= i; p *= p*(3. - 2.*p);
  p.xy = texture(s_noise, (p.xy + i.xy + vec2(37, 17)*i.z + .5)/256., -100.).yx;
  return mix(p.x, p.y, p.z);
}

float hash(float h) {
return pn(vec3(h, -h, h + 134.23453));
}

float noise(vec3 x) {
vec3 p = floor(x);
vec3 f = fract(x);
f = f * f * (3.0 - 2.0 * f);

float n = p.x + p.y * 157.0 + 113.0 * p.z;
return mix(
    mix(mix(hash(n + 0.0), hash(n + 1.0), f.x),
        mix(hash(n + 157.0), hash(n + 158.0), f.x), f.y),
    mix(mix(hash(n + 113.0), hash(n + 114.0), f.x),
        mix(hash(n + 270.0), hash(n + 271.0), f.x), f.y), f.z) * 2. - 1.;
}