Comping Gen

generator/comping_rhythm.py

@@ -64,7 +64,7 @@ def flatten(inputs):
   result['duration'] = generator.model.rational(cursor)
   return result
 
-def validate_events(events, part):
+def validate_events(events, part, lengths=None):
   ordered = sorted(events, key=lambda e: e.start)
   for e in ordered:
     duration = e.end - e.start
@@ -80,13 +80,20 @@ def validate_events(events, part):
       raise ValueError('electric comping requires chord events')
   if any(a.end > b.start for a, b in zip(ordered, ordered[1:])):
     raise ValueError('separate comping events cannot overlap; use one combined sustain')
+  if part == 'acoustic' and lengths is not None:
+    cursor = fractions.Fraction()
+    for length in lengths:
+      first = next((e for e in ordered if cursor <= e.start < cursor + length), None)
+      if first and first.lane not in ('bass', 'combined'):
+        raise ValueError('first acoustic attack in each measure must include bass')
+      cursor += length
 
 def fit(pattern, measure, prior, part, *, anticipate=False, limit=None):
   """Bind a complete figure to written harmony, with bounded early arrivals."""
   length = generator.model.fraction(measure['duration'])
   limit = length if limit is None else min(length, limit)
   harmony = spans(measure, prior)
-  events, exceptions = [], []
+  events, exceptions, available = [], [], []
   for row in pattern['events']:
     start = fractions.Fraction(row['onset'])
     end = min(start + fractions.Fraction(row['duration']), limit)
@@ -96,6 +103,22 @@ def fit(pattern, measure, prior, part, *, anticipate=False, limit=None):
     if active is None or active[2] is None:
       exceptions.append(('space', 'no written harmony at ' + str(start)))
       continue
+    available.append((dict(row), start, end, active))
+  lengths = tuple(map(fractions.Fraction, pattern.get('lengths', (length,))))
+  if part == 'acoustic' and generator.vocabulary.accompaniment(part)['first_attack'] == 'bass_or_combined':
+    cursor = fractions.Fraction()
+    for span in lengths:
+      local = [(row, start) for row, start, _, _ in available if cursor <= start < cursor + span]
+      if local and local[0][0]['layer'] == 'upper':
+        first, onset = local[0]
+        later = next(((row, start) for row, start in local[1:] if row['layer'] == 'bass'), None)
+        first['layer'] = 'bass'
+        first.pop('anticipate', None)
+        if later:
+          later[0]['layer'] = 'upper'
+        exceptions.append(('layer_assignment', f'bass first at {onset}' + (f'; upper exchanged with bass at {later[1]}' if later else '; no later bass to exchange')))
+      cursor += span
+  for row, start, end, active in available:
     _, boundary, chord = active
     target = None
     if anticipate and row.get('anticipate') and row['layer'] in ('upper', 'electric'):
@@ -105,7 +128,7 @@ def fit(pattern, measure, prior, part, *, anticipate=False, limit=None):
     end = min(end, boundary)
     events.append(Attack(row['layer'], start, end, target))
   try:
-    validate_events(events, part)
+    validate_events(events, part, lengths)
   except ValueError:
     return None
   return tuple(events), tuple(exceptions)