Function sanitize_gltf_for_blender

tools/cycles_reference/render.py:186–240

Produce a Blender-friendly copy of the bistro glTF. Bloom's bistro.gltf lists every texture twice: once as `foo.png` (the original source from FBX2glTF) and once as `foo.dds` via the `MSFT_texture_dds` extension. The `.png` files were removed after `etcpak.sh` converted them to BC7

(src_path)

def sanitize_gltf_for_blender(src_path):
    """Produce a Blender-friendly copy of the bistro glTF.

    Bloom's bistro.gltf lists every texture twice: once as `foo.png` (the
    original source from FBX2glTF) and once as `foo.dds` via the
    `MSFT_texture_dds` extension. The `.png` files were removed after
    `etcpak.sh` converted them to BC7 DDS, so Blender's glTF importer
    crashes trying to pack the missing PNGs.

    Blender 5.0 can load DDS natively, so we generate a patched copy with
    every missing `.png` URI rewritten to its existing `.dds` sibling and
    the MSFT_texture_dds extension stripped from textures. The patched
    file is cached next to the original so we only do this once.
    """
    base_dir = os.path.dirname(src_path)
    out_path = os.path.join(base_dir, "bistro_blender.gltf")

    # Regenerate if missing or older than source
    if (os.path.isfile(out_path)
            and os.path.getmtime(out_path) >= os.path.getmtime(src_path)):
        return out_path

    with open(src_path, "r") as f:
        g = json.load(f)

    patched = 0
    for im in g.get("images", []):
        uri = im.get("uri", "")
        if not uri:
            continue
        full = os.path.join(base_dir, uri)
        if os.path.exists(full):
            continue
        if uri.lower().endswith(".png"):
            dds = uri[:-4] + ".dds"
            if os.path.exists(os.path.join(base_dir, dds)):
                im["uri"] = dds
                patched += 1

    # Strip MSFT_texture_dds extension from textures — each texture now
    # resolves directly to the DDS source (or an untouched real PNG).
    for tex in g.get("textures", []):
        exts = tex.get("extensions")
        if exts and "MSFT_texture_dds" in exts:
            del exts["MSFT_texture_dds"]
            if not exts:
                del tex["extensions"]
    used = g.get("extensionsUsed", [])
    if "MSFT_texture_dds" in used:
        used.remove("MSFT_texture_dds")

    with open(out_path, "w") as f:
        json.dump(g, f)
    print(f"[cycles_reference] wrote sanitized gltf ({patched} png->dds URIs): {out_path}")
    return out_path


def import_scene_gltf():