WorldOptimiser

Automatic World Optimization for ReplayMod Compatibility

A Minecraft Forge mod that automatically optimizes worlds when mod changes are detected, specifically designed to solve ReplayMod block ID mismatch issues.

🎯 Purpose

This mod was created to solve a critical issue with ReforgedPlay Mod (version 0.3.1) where adding or removing mods that contain blocks, models, or textures causes ReplayMod to display incorrect textures and models in replay recordings.

The Problem

ReplayMod works perfectly when a world is generated with a fixed set of mods
Issues arise when you add or remove mods containing blocks, models, or textures
This changes the reference ID list, causing ReplayMod to jumble block IDs
Previous manual fix: Download world → Open in singleplayer → Manually optimize → Re-upload
This was tedious and risky for server environments where mods need to be changed on-the-fly

The Solution

WorldOptimiser automatically detects mod list changes and triggers the world optimization process that you would normally do manually through the "Optimize World" button in singleplayer. This recalibrates the ID mappings and fixes ReplayMod compatibility issues.

✨ Features

Automatic Detection: Monitors for mod additions, removals, and version changes
Smart Optimization: Only runs when actual mod changes are detected
Server-Side: Works on both dedicated servers and integrated servers
Non-Intrusive: Runs seamlessly in the background during world startup
Replay-Safe: Ensures your ReplayMod recordings display correctly after mod changes

🔧 How It Works

Startup Check: When a world loads, the mod reads the saved mod list from level.dat
Comparison: Compares the saved mod list with currently loaded mods
Detection: Identifies any additions, removals, or version changes
Optimization: Automatically runs the world optimization process if changes are detected
Completion: World starts normally with updated ID mappings

📋 Requirements

Minecraft: 1.20.1
Forge: 47.4.0 or higher
Java: 17+

📦 Installation

Download the latest release from the releases page
Place worldoptimiser-1.0.jar in your mods folder
Start your server/world - the mod will automatically handle optimization when needed

🎮 Usage

No configuration required! The mod works automatically:

Install the mod
Add/remove other mods as needed
Start your world - optimization happens automatically if mod changes are detected
Your ReplayMod recordings will now display correctly

📝 Log Output

When the mod detects changes, you'll see messages like:

[Server thread/WARN] [worldoptimiser]: Detected new mods world will be optimised on startup
[Server thread/INFO] [worldoptimiser/worldupgrader]: World will be optimised it may take a while, please wait...
[Server thread/INFO] [worldoptimiser/worldupgrader]: World optimisation complete

🐛 Known Issues

World optimization can take some time for large worlds
The process blocks world startup until completion (this is necessary for proper ID remapping)

👨‍💻 Created For

This mod was specifically created for @protagnst to solve ReplayMod compatibility issues in their content creation workflow.

💼 Custom Development

Need a custom mod solution for your specific use case? I'm available for hire for custom Minecraft mod development and similar technical solutions.

Contact: Available for custom development work - reach out if you have similar issues that need solving!

📄 Technical Details

Mod ID: worldoptimiser
Version: 1.0
Author: Pelotrio

Compatibility Note

This issue was specific to ReforgedPlay Mod v0.3.1 on Forge 1.20.1. Previous versions (Forge 1.16.5 and Fabric versions) handled ID changes automatically, but this functionality was lost in the 1.20.1 Forge version.

🔧 For Developers

The mod hooks into Forge's mod loading events and world startup to:

Detect mod list changes via ModMismatchEvent
Read/compare mod lists stored in world NBT data
Trigger Minecraft's built-in WorldUpgrader when needed
Ensure compatibility with ReplayMod's block ID system

This mod solves a specific technical issue with ReplayMod compatibility. If you're experiencing similar block ID or texture mapping issues after mod changes, this tool automates the manual optimization process that was previously required.