95 lines
3.6 KiB
Python
95 lines
3.6 KiB
Python
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"""pingpong_bake.py — bake a clip into a palindrome (forward + reversed) loop.
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Plays the clip forward, then backward, as ONE animation: frames [0..N] followed by
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[N-1..1] mirrored (total 2N). The final frame equals frame 0 exactly, so Godot's
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LoopMode.Linear wraps with zero pose gap and zero root drift — the character returns
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to its start point by construction. The trade-off: motion direction reverses at the
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turn point and at the wrap (inherent to the tactic).
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Usage:
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blender --background --python tools/pingpong_bake.py -- \
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--src <in.glb> --out <out.glb> --name <NewClipName>
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"""
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import bpy, sys, argparse
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def parse():
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argv = sys.argv[sys.argv.index("--")+1:] if "--" in sys.argv else []
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p = argparse.ArgumentParser()
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p.add_argument("--src", required=True)
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p.add_argument("--out", required=True)
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p.add_argument("--name", required=True, help="clip name baked into the output")
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return p.parse_args(argv)
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def action_fcurves(a):
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"""All fcurves across Blender 5 slotted-action layers/strips (legacy fallback)."""
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if hasattr(a, "fcurves") and getattr(a, "fcurves", None) is not None:
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return list(a.fcurves)
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fcs = []
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for layer in getattr(a, "layers", []):
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for strip in layer.strips:
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for bag in strip.channelbags:
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fcs.extend(bag.fcurves)
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return fcs
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def main():
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a = parse()
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bpy.ops.wm.read_factory_settings(use_empty=True)
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bpy.ops.import_scene.gltf(filepath=a.src)
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arm = next(o for o in bpy.data.objects if o.type == 'ARMATURE')
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act = arm.animation_data.action
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if getattr(act, "slots", None) and arm.animation_data.action_slot is None:
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arm.animation_data.action_slot = act.slots[0]
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f0, f1 = int(act.frame_range[0]), int(act.frame_range[1])
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n = f1 - f0
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print(f"[pingpong] src clip '{act.name}' frames {f0}..{f1} -> palindrome 0..{2*n}")
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# extend every fcurve in place: append mirrored keys [N-1..0] after frame N
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for fc in action_fcurves(act):
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vals = [fc.evaluate(f0 + k) for k in range(n + 1)]
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base = len(fc.keyframe_points)
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fc.keyframe_points.add(n) # frames N+1 .. 2N
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# rewrite ALL points to a clean dense 0..2N ramp (handles f0 offset too)
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total = 2 * n
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need = total + 1
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have = base + n
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if have < need:
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fc.keyframe_points.add(need - have)
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elif have > need:
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for _ in range(have - need):
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fc.keyframe_points.remove(fc.keyframe_points[-1], fast=True)
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for k in range(need):
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v = vals[k] if k <= n else vals[2 * n - k]
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kp = fc.keyframe_points[k]
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kp.co = (k, v)
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kp.interpolation = 'LINEAR'
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fc.update()
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act.name = a.name
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# drop NLA tracks that came in with the import — only our palindrome track may export
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for t in list(arm.animation_data.nla_tracks):
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arm.animation_data.nla_tracks.remove(t)
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# single NLA track named = clip name (same convention as cc_retarget.py)
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track = arm.animation_data.nla_tracks.new()
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track.name = a.name
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strip = track.strips.new(a.name, 0, act)
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strip.name = a.name
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arm.animation_data.action = None
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for o in [o for o in bpy.data.objects if o.type == 'MESH']:
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bpy.data.objects.remove(o, do_unlink=True)
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bpy.context.scene.frame_start = 0
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bpy.context.scene.frame_end = 2 * n
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bpy.ops.export_scene.gltf(
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filepath=a.out,
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export_animation_mode="NLA_TRACKS",
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export_force_sampling=True,
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export_optimize_animation_size=False,
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)
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print(f"[pingpong] EXPORTED {a.out} clip '{a.name}' ({2*n+1} frames)")
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if __name__ == "__main__":
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main()
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