157 lines
3.6 KiB
GLSL
157 lines
3.6 KiB
GLSL
// Copypasted from Mark Jarzynski and Marc Olano, Hash Functions for GPU Rendering, Journal of Computer Graphics Techniques (JCGT), vol. 9, no. 3, 21-38, 2020
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// http://www.jcgt.org/published/0009/03/02/
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// https://www.shadertoy.com/view/XlGcRh
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// xxhash (https://github.com/Cyan4973/xxHash)
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// From https://www.shadertoy.com/view/Xt3cDn
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uint xxhash32(uint p)
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{
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const uint PRIME32_2 = 2246822519U, PRIME32_3 = 3266489917U;
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const uint PRIME32_4 = 668265263U, PRIME32_5 = 374761393U;
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uint h32 = p + PRIME32_5;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 = PRIME32_2*(h32^(h32 >> 15));
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h32 = PRIME32_3*(h32^(h32 >> 13));
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return h32^(h32 >> 16);
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}
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uint xxhash32(uvec2 p)
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{
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const uint PRIME32_2 = 2246822519U, PRIME32_3 = 3266489917U;
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const uint PRIME32_4 = 668265263U, PRIME32_5 = 374761393U;
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uint h32 = p.y + PRIME32_5 + p.x*PRIME32_3;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 = PRIME32_2*(h32^(h32 >> 15));
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h32 = PRIME32_3*(h32^(h32 >> 13));
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return h32^(h32 >> 16);
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}
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uint xxhash32(uvec3 p)
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{
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const uint PRIME32_2 = 2246822519U, PRIME32_3 = 3266489917U;
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const uint PRIME32_4 = 668265263U, PRIME32_5 = 374761393U;
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uint h32 = p.z + PRIME32_5 + p.x*PRIME32_3;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 += p.y * PRIME32_3;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 = PRIME32_2*(h32^(h32 >> 15));
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h32 = PRIME32_3*(h32^(h32 >> 13));
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return h32^(h32 >> 16);
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}
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uint xxhash32(uvec4 p)
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{
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const uint PRIME32_2 = 2246822519U, PRIME32_3 = 3266489917U;
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const uint PRIME32_4 = 668265263U, PRIME32_5 = 374761393U;
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uint h32 = p.w + PRIME32_5 + p.x*PRIME32_3;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 += p.y * PRIME32_3;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 += p.z * PRIME32_3;
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h32 = PRIME32_4*((h32 << 17) | (h32 >> (32 - 17)));
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h32 = PRIME32_2*(h32^(h32 >> 15));
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h32 = PRIME32_3*(h32^(h32 >> 13));
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return h32^(h32 >> 16);
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}
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// https://www.pcg-random.org/
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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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uvec2 pcg2d(uvec2 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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// http://www.jcgt.org/published/0009/03/02/
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uvec3 pcg3d(uvec3 v) {
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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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// http://www.jcgt.org/published/0009/03/02/
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uvec3 pcg3d16(uvec3 v)
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{
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v = v * 12829u + 47989u;
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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.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 >>= 16u;
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return v;
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}
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// http://www.jcgt.org/published/0009/03/02/
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uvec4 pcg4d(uvec4 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 >> 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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uint rand01_state = 0;
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uint rand() {
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return rand01_state = xxhash32(rand01_state);
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}
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uint rand_range(uint rmax) {
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return rand() % rmax;
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}
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float uintToFloat01(uint x) {
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return uintBitsToFloat(0x3f800000 | (x & 0x007fffff)) - 1.;
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}
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float rand01() {
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return uintToFloat01(rand());
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}
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vec3 rand3_f01(uvec3 seed) {
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uvec3 v = pcg3d(seed);
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return vec3(uintToFloat01(v.x), uintToFloat01(v.y), uintToFloat01(v.z));
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} |