float turbulence_2d(int octaves, float lacunarity,
float gain, float scale,
float x, float y)
{
float total = 0.f;
float amplitude = 1.f;
float max = 0.f;
for(int i = 0; i < octaves; ++i)
{
max += amplitude;
total += fabs(raw_noise_2d(x * scale, y * scale)) * amplitude;
scale *= lacunarity;
amplitude *= gain;
}
return total / max;
}
// 2D Multi-octave Simplex noise.
//
// For each octave, a higher frequency/lower amplitude function will be added to the original.
// The higher the persistence [0-1], the more of each succeeding octave will be added.
float octave_noise_2d( const float octaves, const float persistence, const float scale, const float x, const float y )
{
float total = 0;
float frequency = scale;
float amplitude = 1;
// We have to keep track of the largest possible amplitude,
// because each octave adds more, and we need a value in [-1, 1].
float maxAmplitude = 0;
for( int i = 0; i < octaves; i++ )
{
total += raw_noise_2d( x * frequency, y * frequency ) * amplitude;
frequency *= 2;
maxAmplitude += amplitude;
amplitude *= persistence;
}
return total / maxAmplitude;
}
double Simplex::raw_2d(const double& x, const double& y) {
return raw_noise_2d(x,y);
}
// 2D Scaled Simplex raw noise.
//
// Returned value will be between loBound and hiBound.
double scaled_raw_noise_2d( const double loBound, const double hiBound, const double x, const double y ) {
return raw_noise_2d(x, y) * (hiBound - loBound) / 2 + (hiBound + loBound) / 2;
}
// 2D Scaled Simplex raw noise.
//
// Returned value will be between loBound and hiBound.
float scaled_raw_noise_2d( const float loBound, const float hiBound, const float x, const float y ) {
return raw_noise_2d(x, y) * (hiBound - loBound) / 2 + (hiBound + loBound) / 2;
}
