144 lines
2.6 KiB
HLSL
144 lines
2.6 KiB
HLSL
#ifndef _SAMPLING_HASHES_HLSL_
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#define _SAMPLING_HASHES_HLSL_
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// Low bias hash from https://github.com/skeeto/hash-prospector
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uint LowBiasHash32(uint x, uint seed = 0)
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{
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x += seed;
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x ^= x >> 16;
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x *= 0x21f0aaad;
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x ^= x >> 15;
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x *= 0xd35a2d97;
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x ^= x >> 15;
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return x;
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}
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// Murmur Hash from https://github.com/aappleby/smhasher/wiki/MurmurHash3
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uint MurmurAdd(uint hash, uint item)
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{
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item *= 0xcc9e2d51;
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item = (item << 15) | (item >> 17);
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item *= 0x1b873593;
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hash ^= item;
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hash = (hash << 13) | (hash >> 19);
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hash = hash * 5 + 0xe6546b64;
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return hash;
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}
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uint MurmurFinalize(uint hash)
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{
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hash ^= hash >> 16;
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hash *= 0x85ebca6b;
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hash ^= hash >> 13;
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hash *= 0xc2b2ae35;
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hash ^= hash >> 16;
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return hash;
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}
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uint MurmurHash(uint x, uint seed = 0)
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{
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uint h = seed;
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h = MurmurAdd(h, x);
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return MurmurFinalize(h);
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}
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uint MurmurHash(uint2 x, uint seed = 0)
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{
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uint h = seed;
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h = MurmurAdd(h, x.x);
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h = MurmurAdd(h, x.y);
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return MurmurFinalize(h);
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}
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uint MurmurHash(uint3 x, uint seed = 0)
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{
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uint h = seed;
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h = MurmurAdd(h, x.x);
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h = MurmurAdd(h, x.y);
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h = MurmurAdd(h, x.z);
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return MurmurFinalize(h);
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}
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uint MurmurHash(uint4 x, uint seed = 0)
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{
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uint h = seed;
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h = MurmurAdd(h, x.x);
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h = MurmurAdd(h, x.y);
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h = MurmurAdd(h, x.z);
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h = MurmurAdd(h, x.w);
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return MurmurFinalize(h);
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}
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uint XorShift32(uint rngState)
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{
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rngState ^= rngState << 13;
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rngState ^= rngState >> 17;
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rngState ^= rngState << 5;
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return rngState;
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}
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// From PCG: A Family of Simple Fast Space-Efficient Statistically Good Algorithms for Random Number Generation.
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// and "Hash Functions for GPU Rendering" paper
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uint Pcg(uint v)
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{
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uint state = v * 747796405u + 2891336453u;
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uint word = ((state >> ((state >> 28u) + 4u)) ^ state) * 277803737u;
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return (word >> 22u) ^ word;
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}
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uint2 Pcg2d(uint2 v)
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{
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v = v * 1664525u + 1013904223u;
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v.x += v.y * 1664525u;
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v.y += v.x * 1664525u;
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v = v ^ (v >> 16u);
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v.x += v.y * 1664525u;
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v.y += v.x * 1664525u;
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v = v ^ (v >> 16u);
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return v;
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}
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uint3 Pcg3d(uint3 v)
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{
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v = v * 1664525u + 1013904223u;
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v.x += v.y * v.z;
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v.y += v.z * v.x;
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v.z += v.x * v.y;
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v ^= v >> 16u;
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v.x += v.y * v.z;
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v.y += v.z * v.x;
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v.z += v.x * v.y;
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return v;
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}
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uint4 Pcg4d(uint4 v)
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{
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v = v * 1664525u + 1013904223u;
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v.x += v.y * v.w;
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v.y += v.z * v.x;
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v.z += v.x * v.y;
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v.w += v.y * v.z;
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v = v ^ (v >> 16u);
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v.x += v.y * v.w;
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v.y += v.z * v.x;
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v.z += v.x * v.y;
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v.w += v.y * v.z;
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return v;
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}
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#endif // _SAMPLING_HASHES_HLSL_
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