85 lines
3.0 KiB
Python
85 lines
3.0 KiB
Python
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"""For each finger bone, report how much geometry it actually OWNS (verts where it is the
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dominant influence) and where that geometry sits. On a two-finger hand rig the five-finger
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bone set is present but several chains own nothing, or several chains share one fused mass.
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usage: hand_bone_ownership.py body.glb [side l|r]
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"""
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import json, struct, sys, math
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from pathlib import Path
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from collections import defaultdict
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FING = ("thumb", "index", "middle", "ring", "pinky")
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side = sys.argv[2] if len(sys.argv) > 2 else None
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def read_glb(p):
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d = Path(p).read_bytes()
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length = struct.unpack_from("<I", d, 8)[0]
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off = 12
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g = b_ = None
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while off < length:
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clen, ct = struct.unpack_from("<II", d, off)
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off += 8
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if ct == 0x4E4F534A:
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g = json.loads(d[off:off + clen])
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else:
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b_ = d[off:off + clen]
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off += clen
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return g, b_
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def acc(g, b, i):
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a = g["accessors"][i]
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bv = g["bufferViews"][a["bufferView"]]
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nc = {"SCALAR": 1, "VEC2": 2, "VEC3": 3, "VEC4": 4, "MAT4": 16}[a["type"]]
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fmt = {5121: "B", 5123: "H", 5125: "I", 5126: "f"}[a["componentType"]]
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size = struct.calcsize(fmt) * nc
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stride = bv.get("byteStride") or size
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off = bv.get("byteOffset", 0) + a.get("byteOffset", 0)
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return [struct.unpack_from("<%d%s" % (nc, fmt), b, off + k * stride)
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for k in range(a["count"])], a["componentType"]
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g, b = read_glb(sys.argv[1])
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names = [nd.get("name", "") for nd in g["nodes"]]
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prim = g["meshes"][0]["primitives"][0]
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att = prim["attributes"]
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skin = next(nd["skin"] for nd in g["nodes"] if nd.get("mesh") == 0 and "skin" in nd)
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joints = g["skins"][skin]["joints"]
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jname = [names[j] for j in joints]
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P, _ = acc(g, b, att["POSITION"])
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J, _ = acc(g, b, att["JOINTS_0"])
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W, wt = acc(g, b, att["WEIGHTS_0"])
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wsc = 1.0 if wt == 5126 else (1 / 255 if wt == 5121 else 1 / 65535)
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own = defaultdict(list)
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for vi, (p, jrow, wrow) in enumerate(zip(P, J, W)):
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best = (0.0, None)
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for j, w in zip(jrow, wrow):
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w *= wsc
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if w > best[0]:
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best = (w, jname[j])
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if best[1] and any(t in best[1].lower() for t in FING):
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if side and not best[1].lower().endswith("_" + side):
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continue
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own[best[1]].append(p)
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print(f"{Path(sys.argv[1]).name} dominant-owner geometry per finger bone"
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f"{' (side ' + side + ')' if side else ''}\n")
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print(f" {'bone':20s} {'verts':>7s} {'z-centre':>9s} {'z-span':>8s} {'x-centre':>9s}")
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for fam in FING:
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rows = [(n, v) for n, v in own.items() if fam in n.lower()]
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if not rows:
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print(f" {fam:20s} {'0':>7s} -- owns no geometry --")
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continue
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for n in sorted(r[0] for r in rows):
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ps = own[n]
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zc = sum(p[2] for p in ps) / len(ps) * 100
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zs = (max(p[2] for p in ps) - min(p[2] for p in ps)) * 100
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xc = sum(p[0] for p in ps) / len(ps) * 100
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print(f" {n:20s} {len(ps):7d} {zc:8.1f}cm {zs:7.1f}cm {xc:8.1f}cm")
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print()
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tot = sum(len(v) for v in own.values())
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print(f" total finger-owned verts: {tot}")
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