38 lines
1.0 KiB
Go
38 lines
1.0 KiB
Go
package gen
|
|
|
|
type DoublePerlin struct {
|
|
Amplitude float64
|
|
A Octave
|
|
B Octave
|
|
}
|
|
|
|
func DoublePerlinFromXoroshiro(x Xoroshiro, amplitudes []float64, omin int, lenn int, nmax int) (d DoublePerlin) {
|
|
na := -1
|
|
nb := -1
|
|
if nmax > 0 {
|
|
na = (nmax + 1) >> 1
|
|
nb = nmax - na
|
|
}
|
|
d.A = OctaveFromXoroshiro(x, amplitudes, omin, lenn, na)
|
|
d.B = OctaveFromXoroshiro(x, amplitudes, omin, lenn, nb)
|
|
|
|
for i := lenn - 1; i >= 0 && amplitudes[i] == 0.0; i-- {
|
|
lenn--
|
|
}
|
|
for i := 0; amplitudes[i] == 0.0; i++ {
|
|
lenn--
|
|
}
|
|
var ampInits = []float64{ // (5 ./ 3) * len / (len + 1), len = 2..16
|
|
0, 5 / 6, 10 / 9, 15 / 12, 20 / 15, 25 / 18, 30 / 21, 35 / 24, 40 / 27, 45 / 30,
|
|
50 / 33, 55 / 36, 60 / 39, 65 / 42, 70 / 45, 75 / 48, 80 / 51,
|
|
}
|
|
d.Amplitude = ampInits[lenn]
|
|
return
|
|
}
|
|
|
|
const DoublePerlinNoiseFactor = 337.0 / 331.0
|
|
|
|
func (d *DoublePerlin) Sample(x, y, z float64) float64 {
|
|
return d.Amplitude * (d.A.Sample(x, y, z) + d.B.Sample(x*DoublePerlinNoiseFactor, y*DoublePerlinNoiseFactor, z*DoublePerlinNoiseFactor))
|
|
}
|