big

tools/extract_animation_subset.py

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+#!/usr/bin/env python3
+"""
+Create a compact animation-only GLB from selected actions in a source GLB.
+
+Usage:
+  blender --background --python tools/extract_animation_subset.py -- \
+      <source.glb> <output.glb> <clip> [<clip> ...]
+
+The source skeleton is retained, all meshes and unrelated actions are removed,
+and each requested action is exported as its own NLA track. This keeps external
+authored animation libraries small enough to ship as retargeting sources.
+"""
+import os
+import sys
+
+import bpy
+
+
+argv = sys.argv
+argv = argv[argv.index("--") + 1:] if "--" in argv else []
+if len(argv) < 3:
+    print(
+        "Usage: blender --background --python "
+        "tools/extract_animation_subset.py -- "
+        "<source.glb> <output.glb> <clip> [<clip> ...]"
+    )
+    sys.exit(1)
+
+SOURCE = argv[0]
+OUTPUT = argv[1]
+REQUESTED = argv[2:]
+
+
+def main():
+    bpy.ops.object.select_all(action="SELECT")
+    bpy.ops.object.delete()
+    bpy.ops.import_scene.gltf(filepath=SOURCE)
+
+    armatures = [obj for obj in bpy.data.objects if obj.type == "ARMATURE"]
+    if len(armatures) != 1:
+        print(f"ERROR: expected one armature, found {len(armatures)}")
+        sys.exit(1)
+    armature = armatures[0]
+
+    missing = [name for name in REQUESTED if bpy.data.actions.get(name) is None]
+    if missing:
+        print(f"ERROR: requested actions not found: {missing}")
+        sys.exit(1)
+
+    for obj in list(bpy.data.objects):
+        if obj != armature:
+            bpy.data.objects.remove(obj, do_unlink=True)
+
+    if not armature.animation_data:
+        armature.animation_data_create()
+    for track in list(armature.animation_data.nla_tracks):
+        armature.animation_data.nla_tracks.remove(track)
+    armature.animation_data.action = None
+
+    keep = set()
+    for name in REQUESTED:
+        action = bpy.data.actions[name]
+        action.use_fake_user = True
+        track = armature.animation_data.nla_tracks.new()
+        track.name = name
+        strip = track.strips.new(name, 0, action)
+        strip.name = name
+        track.mute = True
+        keep.add(action)
+
+    for action in list(bpy.data.actions):
+        if action not in keep:
+            bpy.data.actions.remove(action)
+
+    os.makedirs(os.path.dirname(os.path.abspath(OUTPUT)), exist_ok=True)
+    bpy.ops.export_scene.gltf(
+        filepath=OUTPUT,
+        export_format="GLB",
+        export_yup=True,
+        export_animations=True,
+        export_animation_mode="NLA_TRACKS",
+        export_skins=True,
+        export_bake_animation=True,
+    )
+    print(f"Exported {len(keep)} clips to {OUTPUT}")
+
+
+main()