PostFBXImport.py

import unreal

# ---- CONFIG ----
INSTANCE_PREFIX = "MI_"
TEXTURE_PREFIX = "T_"
# texture suffix -> parent material parameter name (case-sensitive!)
PARAMS = {"D": "D", "N": "N", "R": "R", "M": "M"}
# ----------------

eal = unreal.EditorAssetLibrary
mel = unreal.MaterialEditingLibrary


def get_selected_folder():
    """Return the folder selected in the Content Browser."""
    folders = unreal.EditorUtilityLibrary.get_selected_folder_paths()
    if folders:
        path = folders[0]
        # UE5 can return paths like "/All/Game/..."
        if path.startswith("/All/"):
            path = path[4:]
        return path

    # Fallback: use the folder of the first selected asset
    assets = unreal.EditorUtilityLibrary.get_selected_assets()
    if assets:
        pkg = assets[0].get_path_name().split(".")[0]
        return pkg.rsplit("/", 1)[0]

    return None


def pkg_path(asset_path):
    # "/Game/Folder/Name.Name" -> "/Game/Folder/Name"
    return asset_path.split(".")[0]


def configure_texture(tex, suffix):
    """Set sRGB / compression to match the texture's role."""
    if suffix == "D":
        tex.set_editor_property("srgb", True)
        tex.set_editor_property("compression_settings", unreal.TextureCompressionSettings.TC_DEFAULT)
    elif suffix == "N":
        tex.set_editor_property("srgb", False)
        tex.set_editor_property("compression_settings", unreal.TextureCompressionSettings.TC_NORMALMAP)
    else:  # R, M
        tex.set_editor_property("srgb", False)
        tex.set_editor_property("compression_settings", unreal.TextureCompressionSettings.TC_MASKS)
    eal.save_loaded_asset(tex)


def run():
    import_folder = get_selected_folder()
    if not import_folder:
        unreal.log_error("Select a folder (or an asset) in the Content Browser first.")
        return
    unreal.log(f"Processing folder: {import_folder}")

    all_paths = eal.list_assets(import_folder, recursive=True, include_folder=False)

    # index textures and instances by name
    textures, instances = {}, []
    for p in all_paths:
        asset = eal.load_asset(p)
        if isinstance(asset, unreal.Texture2D):
            textures[asset.get_name()] = asset
        elif isinstance(asset, unreal.MaterialInstanceConstant):
            instances.append(asset)

    for mi in instances:
        old_name = mi.get_name()
        base = old_name[len(INSTANCE_PREFIX):] if old_name.startswith(INSTANCE_PREFIX) else old_name

        # assign textures
        for suffix, param in PARAMS.items():
            tex = textures.get(f"{TEXTURE_PREFIX}{base}_{suffix}")
            if tex:
                configure_texture(tex, suffix)
                mel.set_material_instance_texture_parameter_value(mi, param, tex)
            else:
                unreal.log_warning(f"[{base}] missing texture {TEXTURE_PREFIX}{base}_{suffix}")

        mel.update_material_instance(mi)
        eal.save_loaded_asset(mi)

        # rename last (rename_asset fixes references, e.g. on the static mesh)
        if not old_name.startswith(INSTANCE_PREFIX):
            old_path = pkg_path(mi.get_path_name())
            folder = old_path.rsplit("/", 1)[0]
            new_path = f"{folder}/{INSTANCE_PREFIX}{base}"
            if not eal.rename_asset(old_path, new_path):
                unreal.log_warning(f"Could not rename {old_path}")

    unreal.log(f"Processed {len(instances)} material instances")


run()