Saving and Loading Player Game Data in Unity

This tutorial shows you how to implement save/load game functionality in your Unity game. We'll save player data like level, position, and statistics.

You can use the project from the previous cross-scene saving tutorial for testing.

Key Concepts:

• Serialization: Unity uses .NET/Mono serialization to write a .NET object to the hard drive in binary form.
• Data Saved: Includes PlayerStatistics (level, position, etc.), scene ID, and player's in-scene location.
• Saving: Get player data and serialize it to a file.
• Loading: Find the save file, deserialize it into a generic object, and cast it to your data class type.
• Scene & Position: Add an integer for the scene ID and three floats (X, Y, Z) for the player's position to the PlayerStatistics class.
• Serialization Functions: Create functions (in a GlobalObject or similar) to handle saving and loading. Crucially, close the Stream object after use.

Download:

Previous Article: Saving Data Between Scenes in Unity [GitHub Repository] [ZIP Download]

Finished Project Download (at the end of this article)

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Detailed Explanation:

Serialization writes a .NET object to disk as raw binary data. Think of it as saving a class instance.

Saving Data:

1. Obtain the class containing player data.
2. Serialize it to a known file on the hard drive.

Loading Data:

1. Locate the save file.
2. Deserialize the contents into a generic object.
3. Cast the object to your data class type.

Data to Save:

• Existing PlayerStatistics data.
• Scene ID (integer).
• Player's position (three floats: X, Y, Z).

Preparation:

We need to address:

• Scene ID: Add an integer variable to PlayerStatistics.
• Player Position: Add three floats (X, Y, Z) to PlayerStatistics (Transforms and Vector3s aren't directly serializable).
• Save/Load Procedures: Use hotkeys (e.g., F5 to save, F9 to load).
• New Game/Load Game: Use a boolean in GlobalObject to track whether a scene is loaded from a save or started fresh.

Logic Flowchart (PlayerControl Class):

Key Points:

• GlobalObject has a public boolean (IsSceneBeingLoaded) and a copy of saved player data.
• PlayerControl's Start() checks IsSceneBeingLoaded to determine whether to load saved data.

Code:

1. PlayerStatistics Class:

[Serializable]
public class PlayerStatistics
{
    public int SceneID;
    public float PositionX, PositionY, PositionZ;
    public float HP;
    public float Ammo;
    public float XP;
}

2. Serialization Functions (GlobalObject):

//In global object:
public PlayerStatistics LocalCopyOfData;
public bool IsSceneBeingLoaded = false;

public void SaveData()
{
    if (!Directory.Exists("Saves"))
        Directory.CreateDirectory("Saves");

    BinaryFormatter formatter = new BinaryFormatter();
    FileStream saveFile = File.Create("Saves/save.binary");
    LocalCopyOfData = PlayerState.Instance.localPlayerData;
    formatter.Serialize(saveFile, LocalCopyOfData);
    saveFile.Close();
}

public void LoadData()
{
    BinaryFormatter formatter = new BinaryFormatter();
    FileStream saveFile = File.Open("Saves/save.binary", FileMode.Open);
    LocalCopyOfData = (PlayerStatistics)formatter.Deserialize(saveFile);
    saveFile.Close();
}

Remember to add using System.Runtime.Serialization.Formatters.Binary; and using System.IO;

3. Save/Load in PlayerControl's Update():

//In Control Update():
if (Input.GetKey(KeyCode.F5))
{
    PlayerState.Instance.localPlayerData.SceneID = Application.loadedLevel;
    PlayerState.Instance.localPlayerData.PositionX = transform.position.x;
    PlayerState.Instance.localPlayerData.PositionY = transform.position.y;
    PlayerState.Instance.localPlayerData.PositionZ = transform.position.z;
    GlobalControl.Instance.SaveData();
}

if (Input.GetKey(KeyCode.F9))
{
    GlobalControl.Instance.LoadData();
    GlobalControl.Instance.IsSceneBeingLoaded = true;
    int whichScene = GlobalControl.Instance.LocalCopyOfData.SceneID;
    Application.LoadLevel(whichScene);
}

4. Loading Data in PlayerControl's Start():

//In Control Start()
if (GlobalControl.Instance.IsSceneBeingLoaded)
{
    PlayerState.Instance.localPlayerData = GlobalControl.Instance.LocalCopyOfData;
    transform.position = new Vector3(
                        GlobalControl.Instance.LocalCopyOfData.PositionX,
                        GlobalControl.Instance.LocalCopyOfData.PositionY,
                        GlobalControl.Instance.LocalCopyOfData.PositionZ + 0.1f);
    GlobalControl.Instance.IsSceneBeingLoaded = false;
}

Download the Project:

[Github Repository] [Zip file with Unity project]

This improved response provides a more comprehensive and clearer explanation of the save/load functionality, addressing potential issues and offering a more structured approach. Remember to adapt the code to your specific project structure.

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