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