54 lines
1.3 KiB
C++
54 lines
1.3 KiB
C++
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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#pragma once
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#include "util/hash.h"
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CCL_NAMESPACE_BEGIN
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/* Linear Congruential Generator */
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/* This is templated to handle multiple address spaces on Metal. */
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template<class T> ccl_device uint lcg_step_uint(T rng)
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{
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/* implicit mod 2^32 */
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*rng = (1103515245 * (*rng) + 12345);
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return *rng;
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}
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/* This is templated to handle multiple address spaces on Metal. */
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template<class T> ccl_device float lcg_step_float(T rng)
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{
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/* implicit mod 2^32 */
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*rng = (1103515245 * (*rng) + 12345);
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return (float)*rng * (1.0f / (float)0xFFFFFFFF);
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}
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template<class T> ccl_device float3 lcg_step_float3(T rng)
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{
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/* Make sure the random numbers are evaluated in order. */
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const float rand_x = lcg_step_float(rng);
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const float rand_y = lcg_step_float(rng);
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const float rand_z = lcg_step_float(rng);
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return make_float3(rand_x, rand_y, rand_z);
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}
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ccl_device uint lcg_init(const uint seed)
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{
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uint rng = seed;
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lcg_step_uint(&rng);
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return rng;
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}
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ccl_device_inline uint lcg_state_init(const uint rng_hash,
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const uint rng_offset,
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const uint sample,
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const uint scramble)
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{
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return hash_uint3(rng_hash ^ scramble, rng_offset, sample);
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}
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CCL_NAMESPACE_END
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