Educational project demonstrating IL2CPP runtime interaction from native C++ on Android

This project is in very early development. It is raw, minimally tested, and will have bugs. It has been tested on a limited number of devices and Unity versions.

If you encounter issues:

• This is open source — fix it and submit a PR instead of complaining
• Check the issues page first
• Provide full logcat output when reporting crashes
• Understand that IL2CPP internals vary between Unity versions — what works on one game may not work on another

No guarantees. No support promises. Contributions welcome.

UnityRenderer is a research framework that demonstrates how to create and render Unity UI elements entirely from native C++ on Android. It interacts with Unity's IL2CPP runtime to instantiate GameObjects, add UI components (Canvas, Image, Text, Button), handle touch input, and manage a widget-based overlay panel — all without writing any C# code.

• Hook-free UI creation — Uses il2cpp_thread_attach + il2cpp_runtime_invoke for safe object creation from any thread
• Modular widget system — Toggle, SeekBar, Checkbox, Category headers with extensible base class
• Touch input handling — Screen-to-canvas coordinate conversion, hit testing, drag-to-move
• OOP architecture — Clean separation: core/, ui/, input/, entry/ layers
• RAII memory management — unique_ptr widget ownership, no raw new/delete
• Auto-layout engine — Widgets auto-position vertically with configurable spacing
• Deferred font assignment — Fonts created on render thread, assigned to all text components
• Minimal footprint — Single Dobby hook for input polling only

app/src/main/cpp/
├── entry/
│   └── Entry.cpp               ← JNI entry point, init orchestration
├── core/
│   ├── Types.hpp               ← IL2CPP/Unity struct definitions + enums
│   ├── Il2CppRuntime.hpp/cpp   ← IL2CPP lifecycle (library wait, attach, assemblies)
│   ├── Il2CppResolver.hpp/cpp  ← Method/class resolution with caching
│   └── UnityEngine.hpp/cpp     ← Typed function pointers for Unity API
├── ui/
│   ├── Canvas.hpp/cpp          ← Canvas + CanvasScaler + Raycaster
│   ├── Widget.hpp/cpp          ← Abstract base class for all widgets
│   ├── Menu.hpp/cpp            ← Menu controller (layout, drag, visibility)
│   └── widgets/
│       ├── Toggle.hpp/cpp      ← On/off switch with visual feedback
│       ├── SeekBar.hpp/cpp     ← Horizontal slider with fill bar
│       ├── Checkbox.hpp/cpp    ← Checkmark toggle
│       └── Category.hpp/cpp    ← Non-interactive section header
├── input/
│   └── TouchInput.hpp/cpp      ← Touch polling + coordinate conversion
├── util/
│   ├── Log.hpp                 ← Android logcat macros
│   └── Obfuscate.hpp           ← Compile-time string obfuscation
├── Il2cpp/                     ← IL2CPP helper library (xDL-based)
└── xdl/                        ← Enhanced dlopen/dlsym (HexHacking)

1. Library Loading — dlopen("libunity.so") loads the Unity engine into the process
2. IL2CPP Bootstrap — Waits for libil2cpp.so to appear in /proc/self/maps, then resolves all IL2CPP API exports via xDL
3. Thread Attachment — il2cpp_thread_attach(domain) makes our native thread valid for IL2CPP calls
4. API Resolution — Resolves ~40 Unity method pointers (GameObject, Canvas, Image, Text, etc.) from IL2CPP metadata
5. UI Construction — Creates Canvas → Panel → Widgets hierarchy using il2cpp_runtime_invoke
6. Input Hook — Minimal Dobby hook on Canvas.SendWillRenderCanvases for per-frame touch polling and font assignment
7. Touch Loop — Converts screen coordinates to canvas space, hit-tests widgets, handles drag

• Android Studio Arctic Fox or later
• Android NDK 25+ (installed via SDK Manager)
• CMake 3.22.1+
• JDK 11+

git clone https://github.com/springmusk026/UnityRenderer.git
cd UnityRenderer
./gradlew assembleDebug

The output APK will be at app/build/outputs/apk/debug/app-debug.apk

1. Create ui/widgets/YourWidget.hpp inheriting from Widget
2. Implement Create(void* parent) — build your GameObjects
3. Implement OnTouch(int phase, Vec2 localPos) — handle interaction
4. Implement AssignFont(void* font) — set font on your Text components
5. Add factory method in Menu.hpp/cpp
6. Call it in Entry.cpp before Build()

// In Entry.cpp:
menu.AddToggle("Feature [ON]", "Feature [OFF]", false, 1);
menu.AddSeekBar("Value", 0, 100, 50, 2);
menu.AddCheckbox("Option", false, 3);

This project is for educational and research purposes only. It demonstrates IL2CPP runtime internals, Unity's component architecture, and native-managed code interaction patterns. Use responsibly and in compliance with applicable terms of service.

MIT License — see LICENSE for details.