Weave Loader

A runtime mod loader for Minecraft Legacy Edition (Xbox 360 / PS3 / Windows 64-bit port). Weave Loader injects into the game process, hooks engine functions via PDB symbol resolution, and hosts the .NET runtime so mods can be written in C#. Zero game source modifications required.

Features

• DLL injection -- Launcher starts the game suspended, injects the runtime DLL, then resumes
• PDB symbol resolution -- Uses raw PDB parsing (no DIA dependency) to locate game functions by their mangled names at runtime
• Function hooking -- MinHook detours on game lifecycle functions (init, tick, static constructors, rendering)
• Full .NET hosting -- .NET 8 CoreCLR is loaded inside the game process via hostfxr; mods are standard C# class libraries
• Block and item registration -- Create real game objects (Tile, TileItem, Item) by calling the game's own constructors through resolved PDB symbols
• Dynamic texture atlas merging -- Mod textures are merged into copies of the game's atlases at runtime using empty cells; vanilla game files are never touched
• Creative inventory injection -- Mod items appear in the correct creative tabs with proper pagination
• Localized display names -- Mod strings are injected directly into the game's StringTable vector, bypassing inlined GetString calls
• Crash reporting -- Vectored exception handler produces detailed crash logs with register dumps, symbolicated stack traces, and loaded module lists
• Main menu branding -- Renders loader version and mod count on the main menu via the game's own font renderer
• Furnace recipes -- Register smelting recipes with input, output, and XP values
• Event system -- Subscribe to block break, block place, chat, entity spawn, and player join events

Architecture

┌──────────────────────────────────────────────────────────────┐
│                     WeaveLoader.Launcher                     │
│              Starts game, injects runtime DLL                │
└────────────────────────────┬─────────────────────────────────┘
                             │ CreateRemoteThread
┌────────────────────────────▼─────────────────────────────────┐
│                    WeaveLoaderRuntime.dll                     │
│  C++ runtime injected into game process                      │
│                                                              │
│  ┌─────────────┐ ┌──────────────┐ ┌───────────────────────┐ │
│  │ PDB Parser  │ │  Hook Mgr    │ │  .NET Host (hostfxr)  │ │
│  │ (raw_pdb)   │ │  (MinHook)   │ │                       │ │
│  └──────┬──────┘ └──────┬───────┘ └───────────┬───────────┘ │
│         │               │                     │             │
│  ┌──────▼──────┐ ┌──────▼───────┐ ┌───────────▼───────────┐ │
│  │ Symbol      │ │ Game Hooks   │ │ WeaveLoader.Core.dll   │ │
│  │ Resolver    │ │ (lifecycle,  │ │ (mod discovery,        │ │
│  │             │ │  textures,   │ │  lifecycle mgmt)       │ │
│  │             │ │  UI, strings)│ │                        │ │
│  └─────────────┘ └─────────────┘ └───────────┬───────────┘ │
│                                               │             │
│  ┌────────────────────────────────────────────▼───────────┐ │
│  │ Native Exports (C ABI)                                 │ │
│  │ register_block, register_item, add_furnace_recipe, ... │ │
│  └────────────────────────────────────────────────────────┘ │
└──────────────────────────────────────────────────────────────┘
                             │ P/Invoke
┌────────────────────────────▼─────────────────────────────────┐
│                      WeaveLoader.API                         │
│        Public C# API that mod authors reference              │
│                                                              │
│  Registry.Block  ·  Registry.Item  ·  Registry.Recipe        │
│  Registry.Entity ·  Registry.Assets · GameEvents             │
│  Logger · CreativeTab · Identifier · [Mod] attribute         │
└──────────────────────────────────────────────────────────────┘
                             │ implements IMod
┌────────────────────────────▼─────────────────────────────────┐
│                        Mod DLLs                              │
│               ExampleMod, user mods, etc.                    │
└──────────────────────────────────────────────────────────────┘

Project Structure

ModLoader/
├── WeaveLoader.Launcher/      # C# launcher executable
├── WeaveLoaderRuntime/         # C++ DLL injected into the game
│   └── src/
│       ├── dllmain.cpp         # Entry point, init thread
│       ├── PdbParser.cpp       # Raw PDB symbol parsing (no DIA)
│       ├── SymbolResolver.cpp  # Resolves game functions by mangled name
│       ├── HookManager.cpp     # MinHook-based function detouring
│       ├── GameHooks.cpp       # Hook implementations (lifecycle, UI)
│       ├── GameObjectFactory.cpp # Creates Tile/Item objects via resolved ctors
│       ├── CreativeInventory.cpp # Injects mod items into creative tabs
│       ├── ModAtlas.cpp        # Texture atlas merging (terrain.png, items.png)
│       ├── ModStrings.cpp      # String table injection for item names
│       ├── CrashHandler.cpp    # Vectored exception handler + crash logs
│       ├── MainMenuOverlay.cpp # Renders branding text on main menu
│       ├── DotNetHost.cpp      # Hosts .NET CoreCLR via hostfxr
│       ├── NativeExports.cpp   # C exports called by C# via P/Invoke
│       ├── IdRegistry.cpp      # Namespaced ID <-> numeric ID mapping
│       └── LogUtil.cpp         # Timestamped logging to files
├── WeaveLoader.Core/           # C# mod discovery and lifecycle
│   ├── ModDiscovery.cs         # Scans mods/ for IMod implementations
│   ├── ModManager.cs           # Calls lifecycle hooks with error isolation
│   └── WeaveLoaderCore.cs      # Entry points called from C++ runtime
├── WeaveLoader.API/            # C# public API for mod authors
│   ├── IMod.cs                 # Mod interface with lifecycle hooks
│   ├── ModAttribute.cs         # [Mod("id", Name, Version, Author)]
│   ├── Registry.cs             # Static facade for all registries
│   ├── Block/                  # BlockRegistry, BlockProperties, MaterialType
│   ├── Item/                   # ItemRegistry, ItemProperties
│   ├── Recipe/                 # RecipeRegistry (shaped, furnace)
│   ├── Entity/                 # EntityRegistry, EntityDefinition
│   ├── Assets/                 # AssetRegistry (string table access)
│   ├── Events/                 # GameEvents (block break/place, chat, etc.)
│   ├── Logger.cs               # Debug/Info/Warning/Error logging
│   ├── CreativeTab.cs          # Creative inventory tab enum
│   └── Identifier.cs           # Namespaced ID parsing ("namespace:path")
├── ExampleMod/                 # Sample mod demonstrating the API
│   ├── ExampleMod.cs
│   └── assets/
│       ├── blocks/ruby_ore.png
│       └── items/ruby.png
├── build/                      # Shared build output
│   ├── mods/                   # Mod DLLs and assets go here
│   └── logs/                   # weaveloader.log, game_debug.log, crash.log
├── WeaveLoader.sln
├── README.md
└── CONTRIBUTING.md

Building

Prerequisites

• Visual Studio 2022+ with C++ Desktop Development and .NET 8 workloads
• CMake 3.24+
• .NET 8.0 SDK

Build Steps

Build the C++ runtime DLL:

cd WeaveLoaderRuntime
cmake -B build -A x64
cmake --build build --config Release

Build all C# projects (launcher, core, API, example mod):

dotnet build WeaveLoader.sln -c Debug

All outputs land in build/.

Usage

1. Build Weave Loader (see above)
2. Run WeaveLoader.exe -- it prompts for the game executable path on first launch (saved to weaveloader.json)
3. The launcher starts the game suspended, injects WeaveLoaderRuntime.dll, and resumes
4. Mods are loaded from build/mods/ automatically

Log Files

All logs are written to build/logs/:

File	Contents
weaveloader.log	Loader initialization, symbol resolution, hook installation, mod lifecycle
game_debug.log	Game's own OutputDebugString output (captured via hook)
crash.log	Detailed crash reports with symbolicated stack traces

Writing a Mod

1. Create a .NET 8 class library

dotnet new classlib -n MyMod --framework net8.0

2. Reference the API

Add a project reference to WeaveLoader.API:

<ItemGroup>
  <ProjectReference Include="..\WeaveLoader.API\WeaveLoader.API.csproj" />
</ItemGroup>

Set the output to the mods folder:

<PropertyGroup>
  <OutputPath>..\build\mods\$(AssemblyName)</OutputPath>
  <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
</PropertyGroup>

3. Implement IMod

using WeaveLoader.API;
using WeaveLoader.API.Block;
using WeaveLoader.API.Item;
using WeaveLoader.API.Recipe;
using WeaveLoader.API.Events;

[Mod("mymod", Name = "My Mod", Version = "1.0.0", Author = "You")]
public class MyMod : IMod
{
    public void OnInitialize()
    {
        // Register a block
        var oreBlock = Registry.Block.Register("mymod:example_ore",
            new BlockProperties()
                .Material(MaterialType.Stone)
                .Hardness(3.0f)
                .Resistance(15.0f)
                .Sound(SoundType.Stone)
                .Icon("mymod:example_ore")
                .InCreativeTab(CreativeTab.BuildingBlocks)
                .Name("Example Ore"));

        // Register an item
        var gem = Registry.Item.Register("mymod:example_gem",
            new ItemProperties()
                .MaxStackSize(64)
                .Icon("mymod:example_gem")
                .InCreativeTab(CreativeTab.Materials)
                .Name("Example Gem"));

        // Add a smelting recipe
        Registry.Recipe.AddFurnace("mymod:example_ore", "mymod:example_gem", 1.0f);

        // Subscribe to events
        GameEvents.OnBlockBreak += (sender, args) =>
        {
            if (args.BlockId == oreBlock.NumericId)
                Logger.Info("Player broke example ore!");
        };

        Logger.Info("My Mod loaded!");
    }
}

4. Add textures

Place 16x16 PNG textures in your mod's assets folder:

MyMod/
├── assets/
│   ├── blocks/
│   │   └── example_ore.png     # Block texture
│   └── items/
│       └── example_gem.png     # Item texture
├── MyMod.cs
└── MyMod.csproj

The icon name in BlockProperties.Icon() / ItemProperties.Icon() uses the format "modid:texture_name" where texture_name matches the PNG filename (without extension).

5. Build and run

dotnet build MyMod.csproj
# Output goes to build/mods/MyMod/
# Run WeaveLoader.exe to launch with mods

Mod Lifecycle

Mods go through these phases in order:

Phase	Method	When	Use for
PreInit	OnPreInit()	Before vanilla static constructors	Early configuration
Init	OnInitialize()	After vanilla registries are set up	Registering blocks, items, recipes, events
PostInit	OnPostInitialize()	After Minecraft::init completes	Cross-mod interactions, late setup
Tick	OnTick()	Every game tick (~20 Hz)	Per-frame logic
Shutdown	OnShutdown()	When the game exits	Cleanup, saving state

Each mod's lifecycle methods are wrapped in try/catch, so one mod crashing won't take down others.

API Reference

Registry.Block

RegisteredBlock Register(string id, BlockProperties properties)

Creates a real Tile game object with the specified material, hardness, resistance, and sound type. Automatically creates a corresponding TileItem so the block appears in inventory.

Registry.Item

RegisteredItem Register(string id, ItemProperties properties)

Creates a real Item game object. The constructor parameter is derived from the numeric ID to match the game's internal convention (Item::Item(numericId - 256)).

Registry.Recipe

void AddFurnace(string inputId, string outputId, float xp)

Registers a furnace smelting recipe.

GameEvents

event EventHandler<BlockBreakEventArgs> OnBlockBreak;
event EventHandler<BlockPlaceEventArgs> OnBlockPlace;
event EventHandler<ChatEventArgs> OnChat;
event EventHandler<EntitySpawnEventArgs> OnEntitySpawn;
event EventHandler<PlayerJoinEventArgs> OnPlayerJoin;

Logger

Logger.Debug(string message)
Logger.Info(string message)
Logger.Warning(string message)
Logger.Error(string message)

All log output goes to logs/weaveloader.log with timestamps and log level prefixes.

Identifier

Namespaced string IDs follow the "namespace:path" convention (e.g., "mymod:ruby_ore"). If no namespace is provided, "minecraft" is assumed.

ID Ranges

Type	Numeric Range	Notes
Blocks (Tiles)	174 -- 255	82 slots; maps to TileItem in Item::items[]
Items	3000 -- 31999	Constructor param = numericId - 256
Entities	1000 -- 9999	Reserved for mod entities

How It Works Internally

Symbol Resolution

The runtime opens the game's PDB file and parses it using raw_pdb (no dependency on Microsoft's DIA SDK). It searches public, global, and module symbol streams for decorated C++ names like ??0Tile@@IEAA@HPEAVMaterial@@_N@Z (Tile's protected constructor). The resolved RVAs are added to the module base address to get callable function pointers.

Texture Atlas Merging

1. Mod textures are discovered in mods/*/assets/blocks/ and mods/*/assets/items/
2. The vanilla terrain.png (16x32 grid) and items.png (16x16 grid) are loaded via stb_image
3. Empty cells are identified by checking for fully transparent pixels
4. Mod textures are placed into empty cells
5. The merged atlas is written to mods/ModLoader/generated/ -- vanilla game files are never modified
6. A CreateFileW hook temporarily redirects the game's file opens to the merged atlases during init, then is removed once textures are loaded into GPU memory
7. SimpleIcon objects are created for each mod texture with correct UV coordinates

String Table Injection

The game's CMinecraftApp::GetString(int) is a thin wrapper around StringTable::getString(int), which does a vector index lookup. Since MSVC's link-time optimization inlines GetString at call sites like Item::getHoverName, a MinHook detour alone isn't sufficient. The runtime parses the x64 machine code of GetString to locate the RIP-relative reference to app.m_stringTable, then directly resizes the string table's internal vector and writes mod strings at the allocated indices.

Crash Handler

A vectored exception handler catches access violations and other fatal exceptions. It uses the PDB address index (built during initialization) to resolve crash addresses to symbol names, producing crash reports with full register dumps, symbolicated stack traces, and loaded module lists. The handler also intercepts int 3 breakpoints in game code (used by __debugbreak() for assertions) and skips them so execution continues.

License

MIT