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/* ***** Jenkins Lookup3 Hash Functions ***** */
/* Source: http://burtleburtle.net/bob/c/lookup3.c */
#define rot(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
#define mix(a, b, c) \
{ \
a -= c; \
a ^= rot(c, 4); \
c += b; \
b -= a; \
b ^= rot(a, 6); \
a += c; \
c -= b; \
c ^= rot(b, 8); \
b += a; \
a -= c; \
a ^= rot(c, 16); \
c += b; \
b -= a; \
b ^= rot(a, 19); \
a += c; \
c -= b; \
c ^= rot(b, 4); \
b += a; \
}
#define final(a, b, c) \
{ \
c ^= b; \
c -= rot(b, 14); \
a ^= c; \
a -= rot(c, 11); \
b ^= a; \
b -= rot(a, 25); \
c ^= b; \
c -= rot(b, 16); \
a ^= c; \
a -= rot(c, 4); \
b ^= a; \
b -= rot(a, 14); \
c ^= b; \
c -= rot(b, 24); \
}
uint hash_uint(uint kx)
{
uint a, b, c;
a = b = c = 0xdeadbeefu + (1u << 2u) + 13u;
a += kx;
final(a, b, c);
return c;
}
uint hash_uint2(uint kx, uint ky)
{
uint a, b, c;
a = b = c = 0xdeadbeefu + (2u << 2u) + 13u;
b += ky;
a += kx;
final(a, b, c);
return c;
}
uint hash_uint3(uint kx, uint ky, uint kz)
{
uint a, b, c;
a = b = c = 0xdeadbeefu + (3u << 2u) + 13u;
c += kz;
b += ky;
a += kx;
final(a, b, c);
return c;
}
uint hash_uint4(uint kx, uint ky, uint kz, uint kw)
{
uint a, b, c;
a = b = c = 0xdeadbeefu + (4u << 2u) + 13u;
a += kx;
b += ky;
c += kz;
mix(a, b, c);
a += kw;
final(a, b, c);
return c;
}
#undef rot
#undef final
#undef mix
uint hash_int(int kx)
{
return hash_uint(uint(kx));
}
uint hash_int2(int kx, int ky)
{
return hash_uint2(uint(kx), uint(ky));
}
uint hash_int3(int kx, int ky, int kz)
{
return hash_uint3(uint(kx), uint(ky), uint(kz));
}
uint hash_int4(int kx, int ky, int kz, int kw)
{
return hash_uint4(uint(kx), uint(ky), uint(kz), uint(kw));
}
/* Hashing uint or uint[234] into a float in the range [0, 1]. */
float hash_uint_to_float(uint kx)
{
return float(hash_uint(kx)) / float(0xFFFFFFFFu);
}
float hash_uint2_to_float(uint kx, uint ky)
{
return float(hash_uint2(kx, ky)) / float(0xFFFFFFFFu);
}
float hash_uint3_to_float(uint kx, uint ky, uint kz)
{
return float(hash_uint3(kx, ky, kz)) / float(0xFFFFFFFFu);
}
float hash_uint4_to_float(uint kx, uint ky, uint kz, uint kw)
{
return float(hash_uint4(kx, ky, kz, kw)) / float(0xFFFFFFFFu);
}
/* Hashing float or vec[234] into a float in the range [0, 1]. */
float hash_float_to_float(float k)
{
return hash_uint_to_float(floatBitsToUint(k));
}
float hash_vec2_to_float(vec2 k)
{
return hash_uint2_to_float(floatBitsToUint(k.x), floatBitsToUint(k.y));
}
float hash_vec3_to_float(vec3 k)
{
return hash_uint3_to_float(floatBitsToUint(k.x), floatBitsToUint(k.y), floatBitsToUint(k.z));
}
float hash_vec4_to_float(vec4 k)
{
return hash_uint4_to_float(
floatBitsToUint(k.x), floatBitsToUint(k.y), floatBitsToUint(k.z), floatBitsToUint(k.w));
}
/* Hashing vec[234] into vec[234] of components in the range [0, 1]. */
vec2 hash_vec2_to_vec2(vec2 k)
{
return vec2(hash_vec2_to_float(k), hash_vec3_to_float(vec3(k, 1.0)));
}
vec3 hash_vec3_to_vec3(vec3 k)
{
return vec3(
hash_vec3_to_float(k), hash_vec4_to_float(vec4(k, 1.0)), hash_vec4_to_float(vec4(k, 2.0)));
}
vec4 hash_vec4_to_vec4(vec4 k)
{
return vec4(hash_vec4_to_float(k.xyzw),
hash_vec4_to_float(k.wxyz),
hash_vec4_to_float(k.zwxy),
hash_vec4_to_float(k.yzwx));
}
/* Hashing float or vec[234] into vec3 of components in range [0, 1]. */
vec3 hash_float_to_vec3(float k)
{
return vec3(
hash_float_to_float(k), hash_vec2_to_float(vec2(k, 1.0)), hash_vec2_to_float(vec2(k, 2.0)));
}
vec3 hash_vec2_to_vec3(vec2 k)
{
return vec3(
hash_vec2_to_float(k), hash_vec3_to_float(vec3(k, 1.0)), hash_vec3_to_float(vec3(k, 2.0)));
}
vec3 hash_vec4_to_vec3(vec4 k)
{
return vec3(hash_vec4_to_float(k.xyzw), hash_vec4_to_float(k.zxwy), hash_vec4_to_float(k.wzyx));
}
/* Other Hash Functions */
float integer_noise(int n)
{
int nn;
n = (n + 1013) & 0x7fffffff;
n = (n >> 13) ^ n;
nn = (n * (n * n * 60493 + 19990303) + 1376312589) & 0x7fffffff;
return 0.5 * (float(nn) / 1073741824.0);
}
float wang_hash_noise(uint s)
{
s = (s ^ 61u) ^ (s >> 16u);
s *= 9u;
s = s ^ (s >> 4u);
s *= 0x27d4eb2du;
s = s ^ (s >> 15u);
return fract(float(s) / 4294967296.0);
}
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