Find the highest node in your scene tree that needs to be concerned with save data to use as the root of your save file. Use AutoInject to provide the root save chunk to all its descendant nodes.
[!TIP]
Check out the Chickensoft Game Demo for a complete, working example of using SaveFileBuilder to save composed states of everything that needs to be persisted in a game.
using Chickensoft.Introspection;
using Chickensoft.AutoInject;
using Chickensoft.SaveFileBuilder;
using Godot;
[Meta(typeof(IAutoNode))]
public partial class Game : Node3D {
public SaveFile<GameData> SaveFile { get; set; } = default!;
// Provide the root save chunk to all descendant nodes.
ISaveChunk<GameData> IProvide<ISaveChunk<GameData>>.Value() => SaveFile.Root;
public void Setup() {
SaveFile = new SaveFile<GameData>(
root: new SaveChunk<GameData>(
onSave: (chunk) => {
// Use root chunk to get child chunks that were added to us
// lower in the scene tree.
var gameData = new GameData() {
MapData = chunk.GetChunkSaveData<MapData>(),
PlayerData = chunk.GetChunkSaveData<PlayerData>(),
PlayerCameraData = chunk.GetChunkSaveData<PlayerCameraData>()
};
return gameData;
},
onLoad: (chunk, data) => {
// Break up the game data and send it to the child chunks so that
// they can load the data into the nodes they belong to.
chunk.LoadChunkSaveData(data.MapData);
chunk.LoadChunkSaveData(data.PlayerData);
chunk.LoadChunkSaveData(data.PlayerCameraData);
}
),
onSave: async (GameData data) => {
// Save the game data to disk.
var json = JsonSerializer.Serialize(data, JsonOptions);
await FileSystem.File.WriteAllTextAsync(SaveFilePath, json);
},
onLoad: async () => {
// Load the game data from disk.
if (!FileSystem.File.Exists(SaveFilePath)) {
GD.Print("No save file to load :'(");
return null;
}
var json = await FileSystem.File.ReadAllTextAsync(SaveFilePath);
return JsonSerializer.Deserialize<GameData>(json, JsonOptions);
}
);
...
}
}
🍪 Defining Save Chunks
SaveChunks are smaller pieces of save data that are composed together into the overall save file's data. Simply add a chunk to a descendant node of the scene with the root SaveChunk and register it with the root save chunk once you've resolved dependencies with AutoInject.
[Meta(typeof(IAutoNode))]
public partial class Player : CharacterBody3D {
[Dependency]
public ISaveChunk<GameData> GameChunk => this.DependOn<ISaveChunk<GameData>>();
public ISaveChunk<PlayerData> PlayerChunk { get; set; } = default!;
public void Setup() {
...
PlayerChunk = new SaveChunk<PlayerData>(
onSave: (chunk) => new PlayerData() {
GlobalTransform = GlobalTransform,
StateMachine = (PlayerLogic)PlayerLogic,
Velocity = Velocity
},
onLoad: (chunk, data) => {
GlobalTransform = data.GlobalTransform;
Velocity = data.Velocity;
PlayerLogic.RestoreFrom(data.StateMachine);
PlayerLogic.Start();
}
);
...
}
public void OnResolved() {
// Add a child to our parent save chunk (the game chunk) so that it can
// look up the player chunk when loading and saving the game.
GameChunk.AddChunk(PlayerChunk);
...
}
}
Once a save chunk has been added to a parent save chunk, the parent save chunk can access it from the callbacks specified by onSave and onLoad, querying its data or forcing it load data into its node.
