Soloing

generator/solo/profiles.py

@@ -0,0 +1,55 @@
+"""Sounding-register references and hard solo instrument domains."""
+from __future__ import annotations
+
+import dataclasses
+from fractions import Fraction as F
+
+import generator.fretboard
+
+
+@dataclasses.dataclass(frozen=True)
+class Instrument:
+  part: str = ''
+  strings: tuple[int, ...] = (1, 2, 3, 4, 5, 6)
+  reference: int | None = None
+  melody_range: tuple[int, int] | None = None
+
+  @property
+  def register(self):
+    tuning = [p for s, p in generator.fretboard.STANDARD_TUNING if s in self.strings]
+    return min(tuning) + 1, max(tuning) + 12
+
+  def permits(self, number):
+    return any(p.string_number in self.strings for p in generator.fretboard.single_positions_for_pitch(F(number)))
+
+  def cost(self, number):
+    return min(1., max(0, abs(number - self.reference) - 4) / 12) if self.reference is not None else 0.
+
+
+UNRESTRICTED = Instrument()
+
+
+def weighted_center(notes):
+  values = sorted((n.pitch.number(), n.end - n.start) for n in notes)
+  total = sum((d for _, d in values), F())
+  elapsed = F()
+  for number, duration in values:
+    elapsed += duration
+    if elapsed >= total / 2:
+      return number
+  return 60
+
+
+def for_part(part, analysis=None):
+  if part not in ('acoustic', 'electric'):
+    raise ValueError('unknown solo instrument: ' + part)
+  strings = (2, 3, 4, 5, 6) if part == 'acoustic' else (1, 2, 3, 4)
+  if analysis is None or not analysis.melody:
+    return Instrument(part, strings)
+  # Analysis contains the prepared concert source. Electric melody is written
+  # two octaves up and sounds one down (parts.build_measure), hence +12.
+  # Use the source voice, never the highest added harmonization voice.
+  shift = 12 if part == 'electric' else 0
+  notes = tuple(n for n in analysis.melody if n.end > analysis.body_offset)
+  return Instrument(part, strings, weighted_center(notes) + shift,
+    (min(n.pitch.number() for n in notes) + shift, max(n.pitch.number() for n in notes) + shift))