random_seq.h

 
 
#pragma once
 
#include "random.h"
#include "hashes.h"
#include "noise.h"
 
namespace ghassanpl::noise
{
    using ghassanpl::integer::splitmix64;
 
 
    uint64_t SquirrelNoise3(uint64_t seed, uint64_t position)
    {
        const uint64_t BIT_NOISE1 = 0xB5297A4DB5297A4D;
        const uint64_t BIT_NOISE2 = 0x68E31DA468E31DA4;
        const uint64_t BIT_NOISE3 = 0x1B56C4E91B56C4E9;
 
        uint64_t mangled = position;
        mangled *= BIT_NOISE1;
        mangled += seed;
        mangled ^= (mangled >> 8);
        mangled += BIT_NOISE2;
        mangled ^= (mangled << 8);
        mangled *= BIT_NOISE3;
        mangled ^= (mangled >> 8);
        return mangled;
    }
 
    [[nodiscard]] constexpr uint32_t SquirrelNoise5(uint32_t seed, int32_t position)
    {
        constexpr uint32_t SQ5_BIT_NOISE1 = 0xd2a80a3f; // 11010010101010000000101000111111
        constexpr uint32_t SQ5_BIT_NOISE2 = 0xa884f197; // 10101000100001001111000110010111
        constexpr uint32_t SQ5_BIT_NOISE3 = 0x6C736F4B; // 01101100011100110110111101001011
        constexpr uint32_t SQ5_BIT_NOISE4 = 0xB79F3ABB; // 10110111100111110011101010111011
        constexpr uint32_t SQ5_BIT_NOISE5 = 0x1b56c4f5; // 00011011010101101100010011110101
 
        auto mangledBits = (uint32_t)position;
        mangledBits *= SQ5_BIT_NOISE1;
        mangledBits += seed;
        mangledBits ^= (mangledBits >> 9);
        mangledBits += SQ5_BIT_NOISE2;
        mangledBits ^= (mangledBits >> 11);
        mangledBits *= SQ5_BIT_NOISE3;
        mangledBits ^= (mangledBits >> 13);
        mangledBits += SQ5_BIT_NOISE4;
        mangledBits ^= (mangledBits >> 15);
        mangledBits *= SQ5_BIT_NOISE5;
        mangledBits ^= (mangledBits >> 17);
        return mangledBits;
    }
 
    constexpr uint32_t Get2dNoiseUint(int32_t indexX, int32_t indexY, uint32_t seed)
    {
        constexpr int PRIME_NUMBER = 198491317; // Large prime number with non-boring bits
        return SquirrelNoise5(indexX + (PRIME_NUMBER * indexY), seed);
    }
 
    constexpr double Get1dNoiseZeroToOne(int32_t index, uint32_t seed)
    {
        constexpr double ONE_OVER_MAX_UINT = (1.0 / (double)0xFFFFFFFF);
        return ONE_OVER_MAX_UINT * (double)SquirrelNoise5(index, seed);
    }
 
    constexpr double Get2dNoiseZeroToOne(int32_t indexX, int32_t indexY, uint32_t seed)
    {
        constexpr double ONE_OVER_MAX_UINT = (1.0 / (double)0xFFFFFFFF);
        return ONE_OVER_MAX_UINT * (double)Get2dNoiseUint(indexX, indexY, seed);
    }
}