/// <summary>
/// Calculate a billow fractal
/// </summary>
/// <param name="x">x location</param>
/// <param name="z">z location</param>
/// <returns></returns>
public float GetValue_Billow(float x, float z)
{
float value = 0f;
float signal = 0f;
float persistence = 1f;
float nx, nz;
x += m_seed;
z += m_seed;
x += m_XOffset;
z += m_ZOffset;
x *= m_frequency;
z *= m_frequency;
for (int octave = 0; octave < m_octaves; octave++)
{
nx = x;
nz = z;
signal = SimplexNoiseGenerator.Generate(nx, nz);
signal = 2f * Mathf.Abs(signal) - 1f;
value += signal * persistence;
x *= m_lacunarity;
z *= m_lacunarity;
persistence *= m_persistence;
}
value += m_YOffset * 2.4f;
return(value);
}
/// <summary>
/// Calculate a ridged multi fractal
/// </summary>
/// <param name="x">x location</param>
/// <param name="z">z location</param>
/// <returns></returns>
public float GetValue_RidgedMulti(float x, float z)
{
float signal = 0.0f;
float value = 0.0f;
float weight = 1.0f;
float offset = 1f;
float gain = m_persistence;
float nx, nz;
x += m_seed;
z += m_seed;
x += m_XOffset;
z += m_ZOffset;
x *= m_frequency;
z *= m_frequency;
for (int octave = 0; octave < m_octaves; octave++)
{
nx = x;
nz = z;
//Get the coherent-noise value from input value and add it to final result
signal = SimplexNoiseGenerator.Generate(nx, nz);
//Make the ridges
signal = Mathf.Abs(signal);
signal = offset - signal;
//Square signal to increase sharpness of ridges.
signal *= signal;
//The weighting from previous octave is applied to the signal.
signal *= weight;
//Weight successive contributions by previous signal.
weight = signal * gain;
if (weight > 1.0)
{
weight = 1.0f;
}
if (weight < 0.0f)
{
weight = 0.0f;
}
//Add the signal to output value.
value += signal * m_spectralWeights[octave];
//Next Octave
x *= m_lacunarity;
z *= m_lacunarity;
}
value = (value * 1.25f) - 1.0f;
value += m_YOffset;
return(value);
}
