How to save/load data in game?

Scripting
#1

Hello. Excuse me if this is a stupid question, but how can I save ingame data when exit, and load again when launch game?
For example, in a scene a Door (or 100) can be OPEN or CLOSED.
There is a way to go through the scene objects list and get their values? Must I use std::fstream in script to save a bin file or there is another way? It is better do this in scene script? Can I do this in visual scripting?

#2

We have som utilities for implementing savesystem for a game (kind of game-specific feature, not a general solution to be in engine). My tips are:

  • You can use Tags to mark actors as savable - for gameplay objects like doors, player, erc. so you can iterate over objects on the scene and get the list of them to save
  • Actors and Scripts are inheriting from SceneObject and implement ISerializable interface in C++ that contains nice ways of data serialization for the gameplay state. Example code:
rapidjson_flax::StringBuffer buffer;
CompactJsonWriter writer(buffer);
writer.SceneObject(myActorOrScript);
String mySavedStatAsString(buffer.GetString());
  • We have some in-build methods to save objects state (eg. used by editor undo system): Actor::ToBytes, Actor::FromBytes, Actor::ToJson, Actor::FromJson

Finally, here I showed C++ more like examples but those methods are also available in C# and Visual Script. The only problem in Visual Script might be the lack of good Arrays support (work in progress). So I would suggest implementing saveystsem in C# or C++.

1 Like
#3

I think it’s clear. My next question was about arrays in visual script, but I’ll wait then xD
Thank you, I’ll coming back to engine.

#4

Is there an easy way to save just one variable like Unity’s PlayerPrefs? I’m wanting to save a high score variable.

#5

We don’t have PlayerPrefs but the game can use file stored in-app data folder which can be a simple json or even plain text.

An example would be:

public static class GameSettings
{
    private static Dictionary<string, string> _data;
    private static string _path;

    public static Dictionary<string, string> Data
    {
        get
        {
            if (_data == null)
                Load();
            return _data;
        }
    }

    /// <summary>
    /// Loads the settings.
    /// </summary>
    public static void Load()
    {
        if (_data != null)
            return;
        _path = Path.Combine(Globals.ProductLocalFolder, "Game.settings");
        _data = new Dictionary<string, string>();
        if (File.Exists(_path))
        {
            var json = File.ReadAllText(_path);
            FlaxEngine.Json.JsonSerializer.Deserialize(_data, json);
        }
    }

    /// <summary>
    /// Saves the current settings.
    /// </summary>
    public static void Save()
    {
        if (_data == null)
            return;
        var json = FlaxEngine.Json.JsonSerializer.Serialize(_data);
        var dir = Path.GetDirectoryName(_path);
        if (!Directory.Exists(dir))
            Directory.CreateDirectory(dir);
        File.WriteAllText(_path, json);
    }
}
#6

Thank you very much! This is kind of how Godot does their save system, so this shouldn’t be too hard for me to use.