114 lines
2.6 KiB
C++
114 lines
2.6 KiB
C++
// Copyright 2009-2021 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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#pragma once
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#include "vec.h"
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namespace embree {
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struct RandomSampler
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{
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unsigned int s;
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};
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__forceinline unsigned int MurmurHash3_mix(unsigned int hash, unsigned int k)
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{
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const unsigned int c1 = 0xcc9e2d51;
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const unsigned int c2 = 0x1b873593;
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const unsigned int r1 = 15;
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const unsigned int r2 = 13;
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const unsigned int m = 5;
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const unsigned int n = 0xe6546b64;
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k *= c1;
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k = (k << r1) | (k >> (32 - r1));
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k *= c2;
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hash ^= k;
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hash = ((hash << r2) | (hash >> (32 - r2))) * m + n;
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return hash;
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}
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__forceinline unsigned int MurmurHash3_finalize(unsigned int 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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__forceinline unsigned int LCG_next(unsigned int value)
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{
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const unsigned int m = 1664525;
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const unsigned int n = 1013904223;
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return value * m + n;
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}
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__forceinline void RandomSampler_init(RandomSampler& self, int id)
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{
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unsigned int hash = 0;
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hash = MurmurHash3_mix(hash, id);
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hash = MurmurHash3_finalize(hash);
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self.s = hash;
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}
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__forceinline void RandomSampler_init(RandomSampler& self, int pixelId, int sampleId)
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{
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unsigned int hash = 0;
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hash = MurmurHash3_mix(hash, pixelId);
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hash = MurmurHash3_mix(hash, sampleId);
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hash = MurmurHash3_finalize(hash);
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self.s = hash;
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}
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__forceinline void RandomSampler_init(RandomSampler& self, int x, int y, int sampleId)
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{
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RandomSampler_init(self, x | (y << 16), sampleId);
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}
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__forceinline int RandomSampler_getInt(RandomSampler& self) {
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self.s = LCG_next(self.s); return self.s >> 1;
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}
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__forceinline unsigned int RandomSampler_getUInt(RandomSampler& self) {
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self.s = LCG_next(self.s); return self.s;
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}
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__forceinline float RandomSampler_getFloat(RandomSampler& self) {
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return (float)RandomSampler_getInt(self) * 4.656612873077392578125e-10f;
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}
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__forceinline float RandomSampler_get1D(RandomSampler& self) {
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return RandomSampler_getFloat(self);
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}
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__forceinline Vec2f RandomSampler_get2D(RandomSampler& self)
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{
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const float u = RandomSampler_get1D(self);
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const float v = RandomSampler_get1D(self);
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return Vec2f(u,v);
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}
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__forceinline Vec3fa RandomSampler_get3D(RandomSampler& self)
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{
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/*
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const float u = RandomSampler_get1D(self);
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const float v = RandomSampler_get1D(self);
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const float w = RandomSampler_get1D(self);
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return Vec3fa(u,v,w);
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*/
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const int u = RandomSampler_getUInt(self);
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const int v = RandomSampler_getUInt(self);
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const int w = RandomSampler_getUInt(self);
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return Vec3fa(srl(Vec3ia(u,v,w), 1)) * 4.656612873077392578125e-10f;
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}
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} // namespace embree
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