std::mutex surf_lock;

    // Load all the images.
    for(const auto& f : file_paths) {
        std::thread([&surf_lock, &surfs](const std::string path) {
            surf_lock.lock();

            surface temp = image::get_image(path);
            if(!temp.null()) {
                surfs.push_back({ std::move(temp), path});
            }

            surf_lock.unlock();
        }, f);
    }