Save System in Garden of the Sea: How to save the state of an open-ended gardening & exploration game in Unity / Amanda Rösler (Neat Corporation)
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The document describes a new save system created for the game Garden of the Sea. Key aspects include: 1. Splitting the game world into multiple scenes for each island/area and separating static and dynamic game objects between scenes. 2. Using a component-based approach where game objects can save their state via a base Saveable class. 3. Loading and initializing game objects and components via asset references, scene loading, and passing saved component states. 4. Discussing design decisions around serialization formats and streaming in new game areas from save data.
![SaveObject Component
using UnityEngine.Addressables;
public class SaveObject : MonoBehaviour {
SaveID id; // unique 128-bit id
AssetReference prefab; // prefab to load
Saveable[] saveables; // Grabbable, etc
...](https://image.slidesharecdn.com/amandarosler-210301105300/85/Save-System-in-Garden-of-the-Sea-How-to-save-the-state-of-an-open-ended-gardening-exploration-game-in-Unity-Amanda-Rosler-Neat-Corporation-19-320.jpg)
![JSON vs Custom Binary Format
public void Save( SaveDataSerializer data ) {
data.Serialize( isInInventory );
data.Serialize( hasBeenUnlocked );
}
public void Load( ParsedSaveComponent data ) {
isInInventory = bool.Parse( data.data[0] );
hasBeenUnlocked = bool.Parse( data.data[1] );
}](https://image.slidesharecdn.com/amandarosler-210301105300/85/Save-System-in-Garden-of-the-Sea-How-to-save-the-state-of-an-open-ended-gardening-exploration-game-in-Unity-Amanda-Rosler-Neat-Corporation-29-320.jpg)
Save System in Garden of the Sea: How to save the state of an open-ended gardening & exploration game in Unity / Amanda Rösler (Neat Corporation)
- 1. Save System in Garden of the Sea Amanda Rösler Neat Corporation November 2020 How to save the state of an open-ended gardening & exploration game in Unity
- 2. Introduction ● Lives in Sweden ● Have worked in game industry since 2011 ● Lead programmer on an indie game called Garden of the Sea
- 3. Neat Corporation ● Indie studio in Stockholm ● 11 employees ● Makes VR games ● Budget Cuts 1 & 2 ● Garden on the Sea
- 5. Garden of the Sea ● Made in Unity ● Early access on Steam ● Gardening, crafting, fishing, trading, quests, animals, etc ● Traveling to multiple islands
- 6. Challenges ● Large world where areas need to stream in & out ● Lots of dynamic objects ● Lots of different types of game objects ● Players can create and destroy objects ● How do you save the game state?!?
- 7. Old Save System ● Code ported from Budget Cuts ● List of added & removed objects in save file ● Remove objects from scene after it was loaded + spawn new ones ● Not the best solution for this game
- 8. New Save System ● Not just a save system... ○ Spawn manager ○ System for initializing components ○ Streaming in new areas
- 9. Scene Handling ● Everything was in one big scene scene
- 10. Scene Handling ● Everything was in one big scene ● Split the scene so that each area/island was in its own scene
- 11. Scene Handling ● Split each island into two additional parts: static dynamic ● One “static” scene ● One “dynamic” scene
- 12. ● Static meshes ● Quests ● Spawn points ● Characters ● Etc Static Scene
- 13. Plants, crafted items, wood logs & other resources = Everything that can be removed from the scene Dynamic Scene
- 14. Why? Two reasons: 1. Spawn all the dynamic objects separately, instead of loading the “dynamic” scene 2. Stream in the static scene further away from the player
- 15. How to Serialize a Reference to a Prefab? ● Serialize path and load with Resources.Load()? ○ Doesn’t work if you move/rename the prefab! ● Serialize GUID from the AssetDatabase? ○ Can’t use AssetDatabase during runtime!
- 16. ● Package provided by Unity ● Easy way to load assets asynchronously ● Each asset is identified by a GUID and and address ○ Address can be changed by user ○ GUID is persistent Addressable Assets System
- 17. ● Asset can be loaded by address or GUID in runtime ● To load by GUID, you need an AssetReference ○ Created from the GUID ○ … or by assigning an asset to it in the inspector Addressable Assets System
- 19. SaveObject Component using UnityEngine.Addressables; public class SaveObject : MonoBehaviour { SaveID id; // unique 128-bit id AssetReference prefab; // prefab to load Saveable[] saveables; // Grabbable, etc ...
- 20. Save File Structure Dynamic Objects Static Objects Saveable Data SaveID AssetReference Transform SaveID Transform SaveID SaveableType SaveableState JSON Soil data BINARY
- 21. Saveable & SaveableState ● All components that need to save some data inherit from Saveable ● Need to implement CreateState() which returns a SaveableState ● SaveableState should contain serializable data (that can be converted to JSON)
- 22. Example: WateringCan public class WateringCan : Saveable { public override WaterState CreateState(){ float amount = GetWaterAmount(); return new WaterState( amount ); } } Inherits from SaveableState!
- 23. Example: WateringCan public class WaterState : SaveableState { public float waterAmount = 0.0f; public WaterState(float a) { waterAmount = a; } } SaveID: 1234, SaveableType: WateringCan, SaveableState: {waterAmount: 0.8f}
- 24. Example: WateringCan public abstract class Saveable : MonoBehavior { SaveableState state = null; void InitState(SaveableState s = null) { if (s == null) state = CreateState(); else state = s; } ...
- 25. Example: WateringCan public class WateringCan : Saveable { public void Initialize() { WaterState s = state as WaterState; SetWaterAmount(s.waterAmount); } ...
- 26. Initialization Flow - New Game 1. Load static scenes 3. Call InitState() on all Saveables, which will in turn call CreateState() 2. Load dynamic scenes 4. Call Initialize() on all Saveables static dynamic
- 27. Initialization Flow - Load Save File 1. Read save file data 2. Load static scenes 3. Spawn dynamic objects 4. Call InitState(state) on all Saveables and pass in the SaveableState from the save file data 5. Call Initialize() on all Saveables static
- 28. Initialization Flow - Reasons ● When Initialize() is called, it’s guaranteed that the object has been assigned its initial data ● Have all initialization logic in one place ● Guaranteed that all objects in the same area have spawned ● Possible to specify the order in which different types of Saveables are initialized
- 29. JSON vs Custom Binary Format public void Save( SaveDataSerializer data ) { data.Serialize( isInInventory ); data.Serialize( hasBeenUnlocked ); } public void Load( ParsedSaveComponent data ) { isInInventory = bool.Parse( data.data[0] ); hasBeenUnlocked = bool.Parse( data.data[1] ); }
- 30. JSON vs Custom Binary Format ● When using JSON, the SaveableState can be converted directly to JSON and back again SaveableState state = someObject.CreateState(); string json = JsonUtility.ToJson( state ); state = JsonUtility.FromJson( json, SaveableState );
- 31. JSON vs Custom Binary Format ● It even works if you add or remove a member variable from the SaveableState ● Easier to maintain compatibility with save files from older versions ● Human-readable
- 32. JSON vs Custom Binary Format ● Drawback: JSON is slow and can result in larger save files ● Converting to/from JSON: around 40 ms for 700 objects ● File size: 2 mb of JSON + additional 3 mb of binary data for the soil/ground state
- 33. Streaming In New Areas ● When the player goes to a new area, the previous area will be unloaded ● Need to save the state of the previous area before it’s unloaded
- 34. Streaming In New Areas ● Save data for each area is stored separately ● Keeps track of which areas are currently loaded and which objects belong to which area Area 1 Area 2
- 35. Moving Items Between Areas ● Scenario: player brings an item from one island to another one ○ Need to move the game object to the other scene ○ Need to associate the save data with the correct area Area 1 Area 2
- 36. Future Improvements ● Performance when saving ● System for saving incrementally over several frames ● JSON conversion on a background thread? ● Replace JSON with BSON or other binary format? ● Compressing the save file?