khodowany
92 lines
4.1 KiB
Python
92 lines
4.1 KiB
Python
from __future__ import annotations
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from itertools import product
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from generator.transposition import mod12
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from generator import harmony
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from generator.model import NATURAL, alteration
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from generator.guitar import MAX_FRET, MIN_FRET, STANDARD_TUNING, TabPosition, WRITTEN_GUITAR_OCTAVE_OFFSET, within_fret_span
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def chord_pitch_classes(symbol: str | dict) -> tuple[int, ...]:
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return harmony.pitch_classes(harmony.parse_symbol(symbol) if isinstance(symbol, str) else symbol)
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def positions_for_string(string_number: int, open_midi: int, pitch_classes: tuple[int, ...]) -> list[TabPosition]:
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result: list[TabPosition] = []
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for fret in range(MIN_FRET, MAX_FRET + 1):
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midi = open_midi + fret
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if mod12(midi) in pitch_classes:
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result.append(TabPosition(string_number, fret, midi))
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return result
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def candidate_score(candidate: tuple[TabPosition, ...], pitch_classes: tuple[int, ...]) -> int:
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fretted = [position.fret for position in candidate if position.fret > 0]
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if not fretted:
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span = 0
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low = 0
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else:
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span = max(fretted) - min(fretted)
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low = min(fretted)
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covered = {mod12(position.midi) for position in candidate}
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missing = len(set(pitch_classes) - covered)
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open_penalty = sum(1 for position in candidate if position.fret == 0)
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return missing * 1000 + span * 80 + abs(low - 5) * 12 + open_penalty * 8 + sum(position.fret for position in candidate)
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def find_playable_voicing(symbol: str | dict) -> list[TabPosition]:
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definition = harmony.parse_symbol(symbol) if isinstance(symbol, str) else symbol
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semantic_degrees = harmony.degrees(definition)
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voicing = dict(semantic_degrees)
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if 7 in voicing and voicing.get(5) == 0:
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del voicing[5]
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if len(voicing) > 4:
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for degree in (11, 9, 5):
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if len(voicing) > 4 and voicing.get(degree) == 0:
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del voicing[degree]
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root = definition.get('root', {'letter': 'c', 'alter': 0})
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root_pc = NATURAL[root['letter']] + alteration(root['alter'])
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pitch_classes = tuple(dict.fromkeys((root_pc + harmony.degree_semitones(d, a)) % 12 for d, a in voicing.items()))
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bass = definition.get('bass')
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bass_pc = (NATURAL[bass['letter']] + alteration(bass['alter'])) % 12 if bass else None
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if bass_pc is not None and bass_pc not in pitch_classes:
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pitch_classes += (bass_pc,)
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if not pitch_classes:
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return []
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string_sets = ((6, 4, 3, 2), (5, 4, 3, 2), (4, 3, 2, 1), (6, 5, 4, 3), (5, 3, 2, 1))
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by_string = {string_number: positions_for_string(string_number, open_midi, pitch_classes) for string_number, open_midi in STANDARD_TUNING}
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best: tuple[TabPosition, ...] | None = None
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best_score = 10**9
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for string_set in string_sets:
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options = [by_string[string_number] for string_number in string_set]
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if any(not item for item in options):
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continue
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for candidate in product(*options):
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if bass_pc is not None and min(candidate, key=lambda p: p.midi).midi % 12 != bass_pc:
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continue
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if not within_fret_span(candidate):
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continue
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covered = {mod12(position.midi) for position in candidate}
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if not set(pitch_classes).issubset(covered):
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continue
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score = candidate_score(candidate, pitch_classes)
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if score < best_score:
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best = candidate
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best_score = score
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return sorted(best or [], key=lambda item: item.midi)
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def pitches_for_voicing(symbol: str | dict) -> list[dict[str, int | str]]:
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definition = harmony.parse_symbol(symbol) if isinstance(symbol, str) else symbol
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from generator.transposition import shift_pitch
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root = definition.get('root', {'letter': 'c', 'alter': 0})
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spellings = {}
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for degree, alter in harmony.degrees(definition).items():
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p = shift_pitch(root, degree - 1, harmony.degree_semitones(degree, alter))
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spellings[(NATURAL[p['letter']] + alteration(p['alter'])) % 12] = p
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if bass := definition.get('bass'):
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spellings[(NATURAL[bass['letter']] + alteration(bass['alter'])) % 12] = bass
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result = []
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for position in find_playable_voicing(definition):
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midi = position.midi + WRITTEN_GUITAR_OCTAVE_OFFSET
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p = spellings[midi % 12].copy()
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p['octave'] = int((midi - NATURAL[p['letter']] - alteration(p['alter'])) // 12 - 1)
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result.append(p)
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return result
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