38 lines
1011 B
Go
38 lines
1011 B
Go
package gen
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type DoublePerlin struct {
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Amplitude float64
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A Octave
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B Octave
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}
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func DoublePerlinFromXoroshiro(x *Xoroshiro, amplitudes []float64, omin int, lenn int, nmax int) (d DoublePerlin) {
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na := -1
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nb := -1
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if nmax > 0 {
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na = (nmax + 1) >> 1
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nb = nmax - na
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}
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d.A = OctaveFromXoroshiro(x, amplitudes, omin, lenn, na)
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d.B = OctaveFromXoroshiro(x, amplitudes, omin, lenn, nb)
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for i := lenn - 1; i >= 0 && amplitudes[i] == 0.0; i-- {
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lenn--
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}
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for i := 0; amplitudes[i] == 0.0; i++ {
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lenn--
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}
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var ampInits = []float64{
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0, 5. / 6, 10. / 9, 15. / 12, 20. / 15, 25. / 18, 30. / 21, 35. / 24, 40. / 27, 45. / 30,
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50. / 33, 55. / 36, 60. / 39, 65. / 42, 70. / 45, 75. / 48, 80. / 51,
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}
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d.Amplitude = ampInits[lenn]
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return
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}
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const DoublePerlinNoiseFactor = 337.0 / 331.0
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func (d *DoublePerlin) Sample(x, y, z float64) float64 {
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return d.Amplitude * (d.A.Sample(x, y, z) + d.B.Sample(x*DoublePerlinNoiseFactor, y*DoublePerlinNoiseFactor, z*DoublePerlinNoiseFactor))
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}
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