Rhythm Patterns

generator/comping.py

@@ -284,6 +284,17 @@ class Canonical:
       offset = sum((generator.model.fraction(m['duration']) for m, _, i in original_group if i < start), fractions.Fraction())
       if original_group[0][2] in self.patterns:
         pattern, anticipate = self.patterns[original_group[0][2]]
+        if offset:
+          # Fit the incoming context before slicing. A raw template sustain
+          # may already have ended at a chord change; projecting it first
+          # would resurrect that note as an unintended new downbeat attack.
+          context = tuple((source if i == index else sources[i], prior if i == index else carried[i], i)
+            for _, _, i in original_group if i <= end)
+          incoming = generator.comping_rhythm.realize(pattern, context, self.part, self.melody, anticipate=anticipate, limit=offset + limit if limit is not None else None, boundary=True)
+          if incoming is None:
+            raise ValueError(f'source measure {source["number"]}: selected groove cannot fit incoming harmony')
+          pattern = {**pattern, 'events': [{'onset': str(e.start), 'duration': str(e.end - e.start),
+            'layer': e.lane, 'anticipate': e.harmonic_time is not None and e.lane in ('upper', 'electric')} for e in incoming.events]}
         pattern = generator.comping_rhythm.project(pattern, offset, tuple(generator.model.fraction(m['duration']) for m, _, _ in group))
         rhythm = generator.comping_rhythm.realize(pattern, group, self.part, self.melody, anticipate=anticipate, limit=limit, boundary=True)
         if rhythm is None: