Function SimplexNoise

lobster/src/simplex.cpp:350–364

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.

// 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 SimplexNoise(const int octaves, const float persistence, const float scale, const float2 &v) {
    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 += SimplexRawNoise(v.x * frequency, v.y * frequency) * amplitude;
        frequency *= 2;
        maxAmplitude += amplitude;
        amplitude *= persistence;
    }
    return total / maxAmplitude;
}

// 3D Multi-octave Simplex noise.
//