PROCITY/pipeline/clips_export.py

#!/usr/bin/env python3
"""PROCITY R41 §41.1 — stage 1 of 2: Mixamo anim-only FBX -> skeleton-only per-clip GLB.

Runs INSIDE Blender:

    BL=/Applications/Blender.app/Contents/MacOS/Blender
    "$BL" --background --python pipeline/clips_export.py -- \
        --list pipeline/clips_r41.json --fbx <dir of the named FBX> --out <staging dir>

Stage 2 is `pipeline/clips_pack.py` (pure python, no Blender): it merges the per-clip GLBs into
the <=6 grouped GLBs under web/models/clips/ and writes web/assets/motion_manifest.json.

WHY TWO STAGES. MIRPAMO's roadmap item "multi-clip single-GLB export" is not built yet, and the
documented Blender-5 slotted-action hazard (MIRPAMO/CLAUDE.md) bites exactly when you try to move
actions between armatures inside one .blend. Exporting one clip per GLB is the proven path — it is
how web/models/peds/sit.glb and look.glb were made (generator "Khronos glTF Blender I/O v5.1.20",
66 nodes, 0 meshes) — and the merge is then a deterministic glTF-level operation with no Blender
version risk at all.

NO RETARGET IS NEEDED and none is performed: the Mixamo bank and PROCITY's ped fleet are the SAME
mixamorig skeleton (rigs.js `_canon` folds mixamorig1/4/... -> mixamorig), which is the whole point
of the house "one canonical clip bank" law. MIRPAMO's retargeter is for foreign skeletons (CMU/BVH)
and for rigging raw meshes; pointing it at a mixamorig->mixamorig pair would only add error, and it
would emit the ped MESH into the clip file, breaking the zero-draw property that makes this round
affordable. `make smoke` is still run as the tool ground-truth check (see E-progress.md).
"""
import json
import os
import sys

import bpy


def argv_after_ddash():
    return sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []


def parse_args(a):
    out = {}
    i = 0
    while i < len(a):
        out[a[i].lstrip("-")] = a[i + 1]
        i += 2
    return out


def reset():
    bpy.ops.wm.read_factory_settings(use_empty=True)


def import_clip(path):
    bpy.ops.import_scene.fbx(filepath=path, automatic_bone_orientation=False,
                             ignore_leaf_bones=False)
    arms = [o for o in bpy.data.objects if o.type == "ARMATURE"]
    if len(arms) != 1:
        raise RuntimeError("expected exactly 1 armature, got %d in %s" % (len(arms), path))
    return arms[0]


def export_glb(arm, out_path, anim_name):
    # name the action == the clip id so the exported animation carries it
    if arm.animation_data and arm.animation_data.action:
        arm.animation_data.action.name = anim_name
    for o in bpy.data.objects:
        o.select_set(o is arm)
    bpy.context.view_layer.objects.active = arm
    kw = dict(filepath=out_path, export_format="GLB",
              export_animations=True, export_animation_mode="ACTIVE_ACTIONS",
              export_skins=True, export_yup=True,
              export_materials="NONE", export_texcoords=False, export_normals=False,
              export_apply=False, use_selection=True)
    try:
        bpy.ops.export_scene.gltf(**kw)
    except TypeError:                       # older/newer exporter arg drift — retry minimal
        bpy.ops.export_scene.gltf(filepath=out_path, export_format="GLB",
                                  export_animations=True, use_selection=True)


def main():
    a = parse_args(argv_after_ddash())
    sel = json.load(open(a["list"]))
    fbx_dir, out_dir = a["fbx"], a["out"]
    os.makedirs(out_dir, exist_ok=True)
    results, fails = [], []
    for gname, g in sel["groups"].items():
        for c in g["clips"]:
            src = os.path.join(fbx_dir, c["file"])
            dst = os.path.join(out_dir, "%s.glb" % c["id"])
            try:
                reset()
                arm = import_clip(src)
                nbones = len(arm.data.bones)
                act = arm.animation_data.action if arm.animation_data else None
                fs, fe = (act.frame_range if act else (0, 0))
                export_glb(arm, dst, c["id"])
                results.append(dict(id=c["id"], group=gname, file=c["file"], bones=nbones,
                                    frame_start=float(fs), frame_end=float(fe),
                                    fps=bpy.context.scene.render.fps,
                                    bytes=os.path.getsize(dst)))
                print("[ok  ] %-22s %-64s bones=%d frames=%.0f..%.0f -> %d B"
                      % (c["id"], c["file"], nbones, fs, fe, os.path.getsize(dst)))
            except Exception as e:                                    # noqa: BLE001
                fails.append(dict(id=c["id"], file=c["file"], err=repr(e)))
                print("[FAIL] %-22s %s: %r" % (c["id"], c["file"], e))
    with open(os.path.join(out_dir, "_export_results.json"), "w") as f:
        json.dump(dict(ok=results, fail=fails), f, indent=1)
    print("\n%d exported / %d failed" % (len(results), len(fails)))


main()