145 lines
3.1 KiB
C++
145 lines
3.1 KiB
C++
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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/** \file
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* \ingroup bli
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*/
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#pragma once
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#include "BLI_float2.hh"
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#include "BLI_float3.hh"
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#include "BLI_math.h"
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#include "BLI_span.hh"
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#include "BLI_utildefines.h"
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namespace blender {
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class RandomNumberGenerator {
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private:
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uint64_t x_;
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public:
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RandomNumberGenerator(uint32_t seed = 0)
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{
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this->seed(seed);
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}
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/**
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* Set the seed for future random numbers.
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*/
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void seed(uint32_t seed)
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{
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constexpr uint64_t lowseed = 0x330E;
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x_ = (static_cast<uint64_t>(seed) << 16) | lowseed;
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}
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void seed_random(uint32_t seed);
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uint32_t get_uint32()
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{
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this->step();
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return static_cast<uint32_t>(x_ >> 17);
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}
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int32_t get_int32()
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{
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this->step();
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return static_cast<int32_t>(x_ >> 17);
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}
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/**
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* \return Random value (0..N), but never N.
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*/
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int32_t get_int32(int32_t max_exclusive)
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{
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BLI_assert(max_exclusive > 0);
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return this->get_int32() % max_exclusive;
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}
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/**
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* \return Random value (0..1), but never 1.0.
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*/
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double get_double()
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{
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return (double)this->get_int32() / 0x80000000;
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}
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/**
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* \return Random value (0..1), but never 1.0.
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*/
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float get_float()
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{
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return (float)this->get_int32() / 0x80000000;
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}
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template<typename T> void shuffle(MutableSpan<T> values)
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{
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/* Cannot shuffle arrays of this size yet. */
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BLI_assert(values.size() <= INT32_MAX);
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for (int i = values.size() - 1; i >= 2; i--) {
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int j = this->get_int32(i);
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if (i != j) {
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std::swap(values[i], values[j]);
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}
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}
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}
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/**
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* Compute uniformly distributed barycentric coordinates.
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*/
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float3 get_barycentric_coordinates()
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{
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float rand1 = this->get_float();
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float rand2 = this->get_float();
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if (rand1 + rand2 > 1.0f) {
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rand1 = 1.0f - rand1;
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rand2 = 1.0f - rand2;
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}
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return float3(rand1, rand2, 1.0f - rand1 - rand2);
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}
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float2 get_unit_float2();
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float3 get_unit_float3();
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float2 get_triangle_sample(float2 v1, float2 v2, float2 v3);
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void get_bytes(MutableSpan<char> r_bytes);
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/**
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* Simulate getting \a n random values.
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*/
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void skip(int64_t n)
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{
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while (n--) {
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this->step();
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}
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}
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private:
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void step()
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{
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constexpr uint64_t multiplier = 0x5DEECE66Dll;
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constexpr uint64_t addend = 0xB;
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constexpr uint64_t mask = 0x0000FFFFFFFFFFFFll;
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x_ = (multiplier * x_ + addend) & mask;
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}
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};
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} // namespace blender
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