| |
| """Motion fingerprint of a binary FBX: the per-curve value ranges. |
| |
| Two exports of the same motion that differ only by a trailing hold share every |
| curve's (min, max) pair, while genuinely different motions do not. Comparing the |
| whole multiset is far stricter than comparing a single peak-to-peak figure, |
| which can coincide by chance. |
| """ |
| import os, struct, sys, zlib |
|
|
| SCALAR = {"Y": 2, "C": 1, "I": 4, "F": 4, "D": 8, "L": 8} |
| ELEM = {"f": 4, "d": 8, "l": 8, "i": 4, "b": 1} |
| FMT = {"f": "f", "d": "d", "l": "q", "i": "i", "b": "b"} |
|
|
|
|
| def probe(path, nd=3): |
| d = open(path, "rb").read() |
| if d[:21] != b"Kaydara FBX Binary \x00": |
| raise ValueError("not a binary FBX") |
| u64 = struct.unpack("<I", d[23:27])[0] >= 7500 |
| NREC = 25 if u64 else 13 |
| curves = [] |
|
|
| def rd_prop(p, want): |
| t = chr(d[p]); s = p; p += 1 |
| if t in SCALAR: p += SCALAR[t]; return p, None |
| if t in ELEM: |
| n, enc, clen = struct.unpack("<III", d[p:p+12]); p += 12 |
| body = clen if enc else n * ELEM[t] |
| raw = d[p:p+body]; p += body |
| if want and n: |
| try: |
| if enc: raw = zlib.decompress(raw) |
| return p, struct.unpack("<%d%s" % (n, FMT[t]), raw[:n*ELEM[t]]) |
| except Exception: return p, None |
| return p, None |
| if t in "SR": |
| ln = struct.unpack("<I", d[p:p+4])[0]; p += 4 + ln; return p, None |
| raise ValueError("bad prop %r" % t) |
|
|
| def rd_node(p): |
| 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; want = name == b"KeyValueFloat"; vals = None |
| for _ in range(nprop): |
| p, v = rd_prop(p, want) |
| if v is not None: vals = v |
| if want and vals: |
| curves.append((round(min(vals), nd), round(max(vals), nd), len(vals))) |
| while p < end: |
| if d[p:p+NREC] == b"\x00"*NREC: p += NREC; break |
| p = rd_node(p) |
| return end |
|
|
| p = 27 |
| while p < len(d) - 160: |
| if d[p:p+NREC] == b"\x00"*NREC: break |
| p = rd_node(p) |
| ranges = tuple(sorted((a, b) for a, b, _ in curves)) |
| return {"num_curves": len(curves), "ranges": ranges, |
| "keys": tuple(sorted(c for _, _, c in curves))} |
|
|
|
|
| if __name__ == "__main__": |
| for f in sys.argv[1:]: |
| r = probe(f) |
| print("%-30s curves=%-5d fingerprint=%s" % ( |
| os.path.basename(f), r["num_curves"], hash(r["ranges"]))) |
|
|
