constexpr double getFade(const double t_) const noexcept { return t_ * t_ * t_ * (t_ * (t_ * 6 - 15) + 10); } constexpr double getLerp(const double t_, const double a_, const double b_) const noexcept { return a_ + t_ * (b_ - a_); } constexpr double makeGrad(const Pint hash_, const double u_, const double v_) const noexcept { return (((hash_ & 1) == 0) ? u_ : -u_) + (((hash_ & 2) == 0) ? v_ : -v_)