mc gen start

2026-07-05 10:25:43 +02:00
parent 201e0dfa44
commit a8b090227b
6 changed files with 433 additions and 0 deletions
@@ -0,0 +1,37 @@
+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))
+}