enne2
139 lines
3.3 KiB
GDScript
139 lines
3.3 KiB
GDScript
extends RefCounted
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## Genera proceduralmente un loop musicale da circo (valzer calliope) in WAV.
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## Nessun file audio esterno: tutto sintetizzato a runtime, con loop seamless.
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const SR := 22050
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static func generate() -> AudioStreamWAV:
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var bpm := 132.0
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var beat := 60.0 / bpm
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var bars := 8
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var total_beats := bars * 3
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var total_seconds := total_beats * beat
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var n := int(SR * total_seconds)
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var mix := PackedFloat32Array()
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mix.resize(n)
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# Melodia (calliope) — 8 battute in 3/4
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var melody := [
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[72, 1.0], [76, 1.0], [79, 1.0],
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[72, 1.0], [76, 1.0], [79, 1.0],
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[69, 1.0], [72, 1.0], [76, 1.0],
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[69, 1.0], [72, 1.0], [76, 1.0],
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[65, 1.0], [69, 1.0], [72, 1.0],
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[65, 1.0], [69, 1.0], [72, 1.0],
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[67, 1.0], [71, 1.0], [74, 1.0],
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[72, 2.0], [0, 1.0],
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]
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# Accompagnamento oom-pah-pah: [basso, [accordo]]
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var chords := [
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[48, [60, 64, 67]],
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[48, [60, 64, 67]],
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[45, [57, 60, 64]],
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[45, [57, 60, 64]],
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[41, [53, 57, 60]],
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[41, [53, 57, 60]],
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[43, [55, 59, 62]],
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[48, [60, 64, 67]],
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]
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# Melodia
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var t := 0.0
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for note in melody:
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var midi: int = note[0]
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var beats: float = note[1]
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var dur := beats * beat
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if midi > 0:
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_add_note(mix, t, dur, _freq(midi), 0.5, "calliope")
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t += dur
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# Accompagnamento
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t = 0.0
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for bar in bars:
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var bass: int = chords[bar][0]
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var chord: Array = chords[bar][1]
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_add_note(mix, t, beat * 0.9, _freq(bass), 0.42, "bass")
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for b in [1, 2]:
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var ct: float = t + b * beat
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for m in chord:
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_add_note(mix, ct, beat * 0.8, _freq(int(m)), 0.16, "chord")
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t += 3.0 * beat
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# Fade in/out (30ms) per loop seamless senza click
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var fade := int(SR * 0.03)
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for i in fade:
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var g := float(i) / fade
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mix[i] *= g
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mix[n - 1 - i] *= g
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# Normalizzazione
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var peak := 0.0
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for i in n:
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var a := absf(mix[i])
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if a > peak:
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peak = a
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var norm := 1.0
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if peak > 0.0:
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norm = 0.9 / peak
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var data := PackedByteArray()
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data.resize(n)
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for i in n:
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var v := int(clampf(mix[i] * norm * 127.0, -128.0, 127.0))
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data[i] = v & 0xFF
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var stream := AudioStreamWAV.new()
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stream.format = AudioStreamWAV.FORMAT_8_BITS
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stream.mix_rate = SR
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stream.data = data
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stream.loop_mode = AudioStreamWAV.LOOP_FORWARD
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stream.loop_begin = 0
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stream.loop_end = n
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return stream
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static func _freq(midi: int) -> float:
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return 440.0 * pow(2.0, (midi - 69) / 12.0)
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static func _square(t: float, f: float) -> float:
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return 1.0 if sin(t * f * TAU) > 0.0 else -1.0
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static func _saw(t: float, f: float) -> float:
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return fmod(t * f, 1.0) * 2.0 - 1.0
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static func _envelope(t: float, dur: float) -> float:
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var a := 0.02
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var r := 0.06
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var e := 1.0
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if t < a:
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e = t / a
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var rem := dur - t
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if rem < r:
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e = minf(e, rem / r)
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return e
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static func _add_note(mix: PackedFloat32Array, start: float, dur: float, freq: float, amp: float, kind: String) -> void:
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var start_i := int(start * SR)
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var cnt := int(dur * SR)
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for i in cnt:
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var idx := start_i + i
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if idx < 0 or idx >= mix.size():
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break
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var t := float(i) / SR
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var env := _envelope(t, dur)
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var s := 0.0
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if kind == "calliope":
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var vib := 1.0 + 0.006 * sin(t * 2.0 * PI * 5.0)
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var f := freq * vib
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s = 0.5 * _square(t, f) + 0.3 * _saw(t, f * 1.004) + 0.2 * _square(t, f * 0.996)
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elif kind == "bass":
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s = 0.6 * _saw(t, freq) + 0.4 * _square(t, freq)
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elif kind == "chord":
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s = 0.5 * _square(t, freq) + 0.5 * _saw(t, freq)
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mix[idx] += s * env * amp
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