noise.go

package mapgen

type PerlinNoisePRNG struct {
  seed, octaves int
  persistence, frequency, amplitude float64
}

func (prng *PerlinNoisePRNG) NoiseAt(x, y float64) float64 {
  n := int(y) * 47 + int(x) + prng.seed
  n = (n << 13) ^ n
  ni := float64( (n * (n*n * 60493 + 19990303) + 1376312589) & 0x7fffffff )
  return (1.0 - ni / 1073741824)
}