File size: 2,982 Bytes
a84fca7 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | #!/usr/bin/env python3
"""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"]))
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