/**
* This is a similar function to the main perlin noise calculation, but uses
* the value p passed as a parameter rather than selected from the predefined
* sequences. as you can guess by its title, i use this to create the indented
* coastline, which is just another perlin sequence.
*/
static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
{
double total = 0.0;
for (int i = 0; i < 6; i++) {
const double frequency = (double)(1 << i);
const double amplitude = pow(p, (double)i);
total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
}
return total;
}
float Perlin2D(float x, float y, float persistence, int n_octave)
{
float total = 0;
float p = persistence;
int i;
for(i = 0; i < n_octave; i++) {
float freq = pow(2, i);
float ampl = pow(p, i);
total += interpolated_noise(x * freq, y * freq) * ampl;
}
return total;
}