static double _simplex_2d_noise(double x,double y,uint32_t octaves,double persistance,double z)
{
double f=1,a=1,total=0;
for(int o=0; o<octaves; o++)
{
total+= (_simplex_noise(x*f/z,y*f/z,o)*a);
f=2*o;
a=persistance*o;
}
return total;
}
static double _simplex_2d_noise(double x, double y, uint32_t octaves, double persistance, double z)
{
double total = 0;
// parametrization of octaves to match power spectrum of real grain scans
static double f[] = {0.4910, 0.9441, 1.7280};
static double a[] = {0.2340, 0.7850, 1.2150};
for(uint32_t o = 0; o < octaves; o++)
{
total += (_simplex_noise(x * f[o] / z, y * f[o] / z, o) * a[o]);
}
return total;
}
