bluenoise.hxx

// Public domain. No guarantees.
// Noise that tends to produce values as far as possible from the current value
// especially with higher depths
class BlueNoise
{
  public:
    BlueNoise(unsigned int seed = 0) : m_rng{seed, 1} { m_previous = m_rng.nextFloat(); }
    float operator()() noexcept
    {
        float maxdist = 0.0f;
        float z0 = 0.0f;
        for (int i = 0; i < m_depth; ++i)
        {
            // nextFloat should produce a uniform random number in range 0.0 - 1.0
            float z1 = m_rng.nextFloat();
            float dist = std::abs(z1 - m_previous);
            if (dist > maxdist)
            {
                maxdist = dist;
                z0 = z1;
            }
        }
        m_previous = z0;
        return m_previous;
    }
    // too low depth isn't that different from regular random numbers
    // too high depth starts pretty much oscillating between very high and very low numbers
    void setDepth(int d) noexcept { m_depth = std::clamp(d, 1, 32); }
    int getDepth() const noexcept { return m_depth; }

  private:
    xenakios::Xoroshiro128Plus m_rng;
    float m_previous = 0.0f;
    int m_depth = 4;
};