SaveDuringPlay

A lightweight, zero-overhead framework for Unity that automatically preserves component state modifications made during Play Mode back into Edit Mode.

Unlike standard engine mechanisms or Cinemachine's specific SaveDuringPlay tool, this package offers a generalized, non-invasive architecture optimized for game balancing, level design tweaking, and real-time inspector modification without manual data copying.

Table of Contents

• Features
• How It Works
• Installation
• Usage
• Performance & Production Stripping
• License

Features

• Zero-Configuration Attribute Syntax: Simply decorate any custom MonoBehaviour script with [SaveDuringPlay].
• Rename & Reparent Robustness: Powered by an automated, serialized GUID architecture that tracks components even if objects are renamed or shifted in the hierarchy during runtime.
• Production-Stripped Design: The runtime footprint compiles down to a completely empty shell in standalone builds, ensuring zero memory and processing overhead in production.
• Full Undo Support: All modifications restored upon exiting Play Mode are fully integrated into Unity's Undo ecosystem (Ctrl+Z supported).
• Multi-Scene & Deactivated Object Support: Seamlessly caches state variables across additive scene configurations and handles inactive GameObjects.

How It Works

When entering or exiting Play Mode, Unity completely flushes the C# domain and destroys runtime clones. SaveDuringPlay bypasses this by utilizing a decoupled editor serialization bridge:

1. Injection: The framework automatically injects a hidden, serialized GUID anchor onto target GameObjects via custom Editor hooks upon script compilation or selection.
2. Snapshot Caching: Upon clicking Stop (ExitingPlayMode), the tool evaluates all registered targets, serializes their public and serialized states into a strict string-to-string JSON dictionary cache, and bridges across the boundary.
3. Restoration: Once settled in Edit Mode (EnteredEditMode), the cache is decompressed and safely overwritten onto the freshly reloaded Edit-mode component structures via EditorJsonUtility.

Installation

Via Git URL (Recommended)

Requires Unity 2022.3 or higher. Open Window -> Package Manager, click the + icon, select Add package from git URL..., and enter the following URL:

https://github.com/ProjectGrinder/SaveDuringPlay.git?path=src/SaveDuringPlay/Assets/Plugins/SaveDuringPlay

Usage

Simply slap the [SaveDuringPlay] attribute onto any class inheriting from MonoBehaviour.

using UnityEngine;
using Takayama.SaveDuringPlay;

[SaveDuringPlay]
public class EnemyBalancer : MonoBehaviour
{
    [SerializeField] private float moveSpeed = 5.5f;
    [SerializeField] private int maxHealth = 100;
    
    // Tweak these values dynamically in the Inspector while playing!
    // When you click Stop, your changes are permanently preserved.
}

That's it! The workflow is completely transparent. The backing system takes care of the infrastructure silently behind the scenes.

Performance & Production Stripping

Architectural efficiency is a core priority of this framework. To prevent editor tooling data from leaking into deployment pipelines, the runtime markers use conditional compilation boundaries combined with ISerializationCallbackReceiver:

// High-level overview of the internal compilation footprint in standalone builds:
public sealed class SaveDuringPlayMarker : MonoBehaviour 
{
    // All GUID allocations, reflection lookups, and serialization logic 
    // are entirely stripped out by the compiler in non-editor environments.
}

In production standalone builds, the component has zero fields, consumes zero bytes of memory, and performs no lifecycle execution.

License

This project is licensed under the MIT License - see the LICENSE file for details.