A cheeky C implementation of "A simple method to construct isotropic quasirandom blue noise point sequences"

blue_noise.c

// based on C++ implementation by syoyo https://gist.github.com/syoyo/831c4b1926aa88c0da9221211723da2d
// http://extremelearning.com.au/a-simple-method-to-construct-isotropic-quasirandom-blue-noise-point-sequences/

#if __cplusplus
extern "C" {
#endif
static inline void sample_point_2d(
    double p[2],
    int i,          // 1, 2, 3, ...
    double jitter,  // > 0
    double random0, // [0..1)
    double random1  // [0..1)
) {
    static const double sqrtkPI = 1.772453850905516;
    static const double varphi = 1.324717957244746;
    static const double alpha0 = 1.0 / varphi;
    static const double alpha1 = 1.0 / (varphi * varphi);
    static const double delta0 = 0.76;
    static const double delta0_sqrtkPI = delta0 * sqrtkPI;
    static const double i0 = 0.700;

    extern double floor(double);
    extern double sqrt(double);
    const double iDouble = (double)i;
    const double iDelta = iDouble - i0;
    const double jitter_scaled = jitter * delta0_sqrtkPI / (4.0 * sqrt(iDelta));
    const double x0 = alpha0 * iDouble + jitter_scaled * random0;
    const double x1 = alpha1 * iDouble + jitter_scaled * random1;
    p[0] = x0 - floor(x0);
    p[1] = x1 - floor(x1);
}
#if __cplusplus
} // extern "C"
#endif

based on C++ implementation by syoyo https://gist.github.com/syoyo/831c4b1926aa88c0da9221211723da2d

and http://extremelearning.com.au/a-simple-method-to-construct-isotropic-quasirandom-blue-noise-point-sequences/