Function materialize_inline_meshes

Scripts/clean_meshes.py:220–290

Rewrite `` `` (MuJoCo's inline-data form) to `` `` by emitting an OBJ next to the rest of the mesh assets. Returns the number of inline meshes materialized. MuJoCo accepts meshes declared inline via ``vertex`` (flat list of 3-tuple floats

(root, mesh_base: Path)

def materialize_inline_meshes(root, mesh_base: Path) -> int:
    """Rewrite ``<mesh vertex="..." face="...">`` (MuJoCo&#x27;s inline-data form)
    to ``<mesh file="...">`` by emitting an OBJ next to the rest of the
    mesh assets. Returns the number of inline meshes materialized.

    MuJoCo accepts meshes declared inline via ``vertex`` (flat list of
    3-tuple floats) and ``face`` (flat list of 3-tuple ints) attributes
    instead of an external ``file``. Unreal's importer can't follow the
    inline form, so we synthesize a real OBJ on disk and rewrite the
    ``<mesh>`` element to point at it. The downstream conversion phase
    then produces a GLB companion just like any other ``file=`` mesh.
    """
    materialized = 0
    mesh_base.mkdir(parents=True, exist_ok=True)
    for mesh_el in list(root.iter("mesh")):
        if mesh_el.get("file"):
            continue
        vertex_attr = mesh_el.get("vertex")
        face_attr = mesh_el.get("face")
        if not vertex_attr or not face_attr:
            continue

        name = mesh_el.get("name")
        if not name:
            print(f"  x Inline mesh has no name; skipping (cannot synthesize filename)")
            continue

        try:
            verts = _parse_floats(vertex_attr)
            faces = [int(t) for t in face_attr.replace(",", " ").split() if t]
        except ValueError as e:
            print(f"  x Failed to parse vertex/face for '{name}': {e}")
            continue

        if len(verts) % 3 != 0 or len(faces) % 3 != 0:
            print(f"  x Inline mesh '{name}' has non-triangular layout "
                  f"(verts={len(verts)}, faces={len(faces)}) — skipping")
            continue

        n_verts = len(verts) // 3
        n_faces = len(faces) // 3

        # Filename-safe stem. MuJoCo names can contain '/' (the scene XML
        # uses slash-paths heavily) which would create stray directories.
        safe_stem = name.replace("/", "_").replace("\\", "_").replace(":", "_")
        obj_path = mesh_base / f"{safe_stem}.obj"

        print(f"\n[inline] Materializing '{name}' -> {obj_path.name} "
              f"({n_verts} verts, {n_faces} faces)")

        # Standard OBJ — vertices are 1-indexed in OBJ but 0-indexed in MuJoCo.
        with open(obj_path, "w", encoding="utf-8") as f:
            f.write(f"# Generated by clean_meshes.py from inline MJCF mesh '{name}'\n")
            for i in range(n_verts):
                f.write(f"v {verts[i*3]:.6f} {verts[i*3+1]:.6f} {verts[i*3+2]:.6f}\n")
            for i in range(n_faces):
                a, b, c = faces[i*3] + 1, faces[i*3+1] + 1, faces[i*3+2] + 1
                f.write(f"f {a} {b} {c}\n")