#ifndef RANDOM_GLSL
#define RANDOM_GLSL

layout(set = 0, binding = 1) uniform texture2D t_noise;
layout(set = 0, binding = 2) uniform sampler s_noise;

float hash(vec4 p) {
    p = fract(p * 0.3183099 + 0.1) - fract(p + 23.22121);
    p *= 17.0;
    return (fract(p.x * p.y * (1.0 - p.z) * p.w * (p.x + p.y + p.z + p.w)) - 0.5) * 2.0;
}

#define M1 2047667443U
#define M2 3883706873U
#define M3 3961281721U

float hash_one(uint q) {
    uint n = ((M3 * q) ^ M2) * M1;

    return float(n) * (1.0 / float(0xffffffffU));
}

float hash_two(uvec2 q) {
    q *= uvec2(M1, M2);
    uint n = q.x ^ q.y;
    n = n * (n ^ (n >> 15));
    return float(n) * (1.0 / float(0xffffffffU));
}

float hash_fast(uvec3 q) {
    q *= uvec3(M1, M2, M3);

    uint n = (q.x ^ q.y ^ q.z) * M1;

    return float(n) * (1.0 / float(0xffffffffU));
}

// 2D, but using shifted 2D textures
float noise_2d(vec2 pos) {
    return textureLod(sampler2D(t_noise, s_noise), pos, 0).x;
}

// 3D, but using shifted 2D textures
float noise_3d(vec3 pos) {
    pos.z *= 15.0;
    uint z = uint(trunc(pos.z));
    vec2 offs0 = vec2(hash_one(z), hash_one(z + 73u));
    vec2 offs1 = vec2(hash_one(z + 1u), hash_one(z + 1u + 73u));
    return mix(textureLod(sampler2D(t_noise, s_noise), pos.xy + offs0, 0).x, textureLod(sampler2D(t_noise, s_noise), pos.xy + offs1, 0).x, fract(pos.z));
}

// 3D version of `snoise`
float snoise3(in vec3 x) {
    uvec3 p = uvec3(floor(x) + 10000.0);
    vec3 f = fract(x);
    //f = f * f * (3.0 - 2.0 * f);
    return mix(
        mix(
            mix(hash_fast(p + uvec3(0, 0, 0)), hash_fast(p + uvec3(1, 0, 0)), f.x),
            mix(hash_fast(p + uvec3(0, 1, 0)), hash_fast(p + uvec3(1, 1, 0)), f.x),
            f.y),
        mix(
            mix(hash_fast(p + uvec3(0, 0, 1)), hash_fast(p + uvec3(1, 0, 1)), f.x),
            mix(hash_fast(p + uvec3(0, 1, 1)), hash_fast(p + uvec3(1, 1, 1)), f.x),
            f.y),
        f.z);
}

// 4D noise
float snoise(in vec4 x) {
    vec4 p = floor(x);
    vec4 f = fract(x);
    f = f * f * (3.0 - 2.0 * f);
    return mix(
        mix(
            mix(
                mix(hash(p + vec4(0, 0, 0, 0)), hash(p + vec4(1, 0, 0, 0)), f.x),
                mix(hash(p + vec4(0, 1, 0, 0)), hash(p + vec4(1, 1, 0, 0)), f.x),
                f.y),
            mix(
                mix(hash(p + vec4(0, 0, 1, 0)), hash(p + vec4(1, 0, 1, 0)), f.x),
                mix(hash(p + vec4(0, 1, 1, 0)), hash(p + vec4(1, 1, 1, 0)), f.x),
                f.y),
            f.z),
        mix(
            mix(
                mix(hash(p + vec4(0, 0, 0, 1)), hash(p + vec4(1, 0, 0, 1)), f.x),
                mix(hash(p + vec4(0, 1, 0, 1)), hash(p + vec4(1, 1, 0, 1)), f.x),
                f.y),
            mix(
                mix(hash(p + vec4(0, 0, 1, 1)), hash(p + vec4(1, 0, 1, 1)), f.x),
                mix(hash(p + vec4(0, 1, 1, 1)), hash(p + vec4(1, 1, 1, 1)), f.x),
                f.y),
            f.z),
        f.w);
}

vec3 rand_perm_3(vec3 pos) {
    return abs(sin(pos * vec3(1473.7 * pos.z + 472.3, 8891.1 * pos.x + 723.1, 3813.3 * pos.y + 982.5)));
}

vec4 rand_perm_4(vec4 pos) {
    return sin(473.3 * pos * vec4(317.3 * pos.w + 917.7, 1473.7 * pos.z + 472.3, 8891.1 * pos.x + 723.1, 3813.3 * pos.y + 982.5) / pos.yxwz);
}

vec3 smooth_rand(vec3 pos, float lerp_axis) {
    return vec3(snoise(vec4(pos, lerp_axis)), snoise(vec4(pos + 400.0, lerp_axis)), snoise(vec4(pos + 1000.0, lerp_axis)));
    vec3 r0 = rand_perm_3(vec3(pos.x, pos.y, pos.z) + floor(lerp_axis));
    vec3 r1 = rand_perm_3(vec3(pos.x, pos.y, pos.z) + floor(lerp_axis + 1.0));
    return r0 + (r1 - r0) * fract(lerp_axis);
}

// Transform normal distribution to triangle distribution.
float norm2tri(float n) {
   // TODO: compare perf with adding two normal noise distributions
   bool flip = n > 0.5;
   n = flip ? 1.0 - n : n;
   n = sqrt(n / 2.0);
   n = flip ? 1.0 - n : n;
   return n;
}
#endif