| |
| """Rig fingerprint of a binary FBX: joint names plus their rest offsets. |
| |
| Joint count alone cannot tell two skeletons apart — two rigs can share a count |
| and still differ in proportions. Each joint's `Lcl Translation` is its offset |
| from its parent, i.e. the bone vector, so the (name, offset) set pins down both |
| topology and bone lengths. |
| """ |
| import math, os, struct, sys |
|
|
| SCALAR = {"Y": 2, "C": 1, "I": 4, "F": 4, "D": 8, "L": 8} |
| ELEM = {"f": 4, "d": 8, "l": 8, "i": 4, "b": 1} |
|
|
|
|
| def probe(path, nd=3): |
| d = open(path, "rb").read() |
| if d[:21] != b"Kaydara FBX Binary \x00": |
| raise ValueError("not a binary FBX") |
| version = struct.unpack("<I", d[23:27])[0] |
| u64 = version >= 7500 |
| NREC = 25 if u64 else 13 |
| bones = {} |
|
|
| def rd_prop(p): |
| t = chr(d[p]); s = p; p += 1 |
| if t in SCALAR: |
| p += SCALAR[t]; return p, (t, d[s + 1:p]) |
| if t in ELEM: |
| n, enc, clen = struct.unpack("<III", d[p:p + 12]); p += 12 |
| p += clen if enc else n * ELEM[t] |
| return p, (t, None) |
| if t in "SR": |
| ln = struct.unpack("<I", d[p:p + 4])[0]; p += 4 |
| v = d[p:p + ln]; p += ln |
| return p, (t, v) |
| raise ValueError("bad prop %r" % t) |
|
|
| def rd_node(p, cur=None): |
| if u64: end, nprop, plen = struct.unpack("<QQQ", d[p:p + 24]); q = p + 24 |
| else: end, nprop, plen = struct.unpack("<III", d[p:p + 12]); q = p + 12 |
| if end == 0 and nprop == 0 and plen == 0: |
| return p + NREC |
| nl = d[q]; q += 1; name = d[q:q + nl]; q += nl |
| p = q; props = [] |
| for _ in range(nprop): |
| p, pr = rd_prop(p); props.append(pr) |
| mine = cur |
| if name == b"Model" and len(props) >= 3 and props[2][1] in (b"LimbNode", b"Root"): |
| mine = props[1][1].split(b"\x00\x01")[0].decode("utf-8", "replace") |
| bones.setdefault(mine, (0.0, 0.0, 0.0)) |
| elif name == b"P" and cur is not None and props and props[0][1] == b"Lcl Translation": |
| vals = [struct.unpack("<d", v)[0] for t, v in props if t == "D" and v and len(v) == 8] |
| if len(vals) >= 3: |
| bones[cur] = tuple(vals[-3:]) |
| while p < end: |
| if d[p:p + NREC] == b"\x00" * NREC: p += NREC; break |
| p = rd_node(p, mine) |
| return end |
|
|
| p = 27 |
| while p < len(d) - 160: |
| if d[p:p + NREC] == b"\x00" * NREC: break |
| p = rd_node(p) |
| sig = tuple(sorted((n, round(x, nd), round(y, nd), round(z, nd)) |
| for n, (x, y, z) in bones.items())) |
| total = sum(math.sqrt(x * x + y * y + z * z) for _, (x, y, z) in bones.items()) |
| return {"num_joints": len(bones), "signature": sig, "bone_length_sum": round(total, 3)} |
|
|
|
|
| if __name__ == "__main__": |
| for f in sys.argv[1:]: |
| r = probe(f) |
| print("%-34s joints=%-4d bone_len_sum=%-12.3f" % ( |
| os.path.basename(f), r["num_joints"], r["bone_length_sum"])) |
|
|
