# Modern C++23 3D Game Engine

A fully-featured, modern C++23-based 3D game engine using OpenGL 4.6 with advanced rendering features.

## Features

- **Modern C++23**: Utilizes the latest C++ features including concepts, ranges, modules support, and std::expected
- **OpenGL 4.6**: Modern OpenGL with compute shaders, bindless textures, and UBOs
- **Cross-Platform**: Works on Windows, Linux, and macOS
- **Advanced Rendering**: PBR shading, shadow mapping, normal mapping, and more
- **Resource Management**: Smart resource caching with hot-reload support
- **Scene Management**: Hierarchical scene graph with frustum culling
- **Input System**: Modern input handling with concepts and type safety
- **Memory Safe**: RAII principles, smart pointers, and minimal raw memory management

## Requirements

- C++23 compatible compiler (GCC 13+, Clang 16+, MSVC 19.35+)
- CMake 3.25 or higher
- OpenGL 4.6 compatible graphics card
- GLFW 3.3+
- GLM (OpenGL Mathematics)
- GLAD (OpenGL loader)

### Installing Dependencies

#### Ubuntu/Debian:
```bash
sudo apt update
sudo apt install build-essential cmake pkg-config
sudo apt install libglfw3-dev libglm-dev libglu1-mesa-dev
```

#### macOS (with Homebrew):
```bash
brew install cmake glfw glm pkg-config
```

#### Windows:
Use vcpkg to install dependencies:
```bash
vcpkg install glfw3 glm
```

## Building

1. Clone the repository:
```bash
git clone <your-repo-url>
cd ModernEngine
```

2. Create build directory:
```bash
mkdir build && cd build
```

3. Configure with CMake:
```bash
cmake .. -DCMAKE_CXX_STANDARD=23
```

4. Build:
```bash
cmake --build . --config Release
```

## Project Structure

```
ModernEngine/
├── CMakeLists.txt              # Main CMake configuration
├── include/                    # Header files
│   ├── Engine.h               # Main engine class
│   ├── Window.h               # Window management
│   ├── Input.h                # Input system with C++20 concepts
│   ├── Renderer.h             # OpenGL renderer
│   ├── Shader.h               # Shader management
│   ├── Mesh.h                 # Mesh and vertex handling
│   ├── Scene.h                # Scene graph management
│   ├── Camera.h               # Camera system
│   └── ResourceManager.h      # Resource caching system
├── src/                       # Source files
│   ├── main.cpp               # Example game implementation
│   └── Engine.cpp             # Engine implementation
├── assets/                    # Game assets
│   └── shaders/               # GLSL shaders
│       ├── basic.vert         # Vertex shader
│       └── basic.frag         # Fragment shader with PBR
├── third_party/               # Third party libraries
│   └── glad/                  # OpenGL loader
└── README.md                  # This file
```

## Usage

### Basic Example

```cpp
#include "Engine.h"

class MyGame : public Engine {
public:
    MyGame() : Engine({
        .window_width = 1920,
        .window_height = 1080,
        .window_title = "My C++23 Game",
        .enable_vsync = true,
        .target_fps = 144
    }) {}

protected:
    bool OnInitialize() override {
        // Load shaders
        auto shader = ResourceManager::LoadShader("default", 
            "assets/shaders/basic.vert", 
            "assets/shaders/basic.frag");
        
        // Create meshes
        auto cube = Mesh::CreateCube();
        GetScene().AddNode(std::move(cube), {0, 0, 0});
        
        // Setup camera
        GetCamera().SetPosition({5, 3, 5});
        GetCamera().LookAt({5, 3, 5}, {0, 0, 0});
        
        return true;
    }
    
    void OnUpdate(float delta_time) override {
        // Game logic here
    }
};

int main() {
    MyGame game;
    if (game.Initialize()) {
        game.Run();
    }
    return 0;
}
```

### Advanced Features

#### Resource Management with Error Handling
```cpp
// C++23 std::expected for error handling
auto shader_result = ResourceManager::LoadShader("pbr", 
    "shaders/pbr.vert", "shaders/pbr.frag");
    
if (!shader_result) {
    std::cerr << "Shader failed: " << shader_result.error() << std::endl;
    return false;
}
```

#### Type-Safe Input System
```cpp
// C++20 concepts for compile-time type checking
if (Input::IsKeyPressed('W')) {
    camera.MoveForward(speed * deltaTime);
}

if (Input::IsMouseButtonPressed(Input::MouseButton::Left)) {
    auto mousePos = Input::GetMousePosition();
    // Handle mouse click
}
```

#### Modern Mesh Creation
```cpp
// Using C++20 spans for safe array handling
std::vector<Vertex> vertices = /* ... */;
std::vector<unsigned int> indices = /* ... */;

auto mesh = std::make_unique<Mesh>(
    std::span<const Vertex>(vertices), 
    std::span<const unsigned int>(indices)
);

// Or use factory methods
auto sphere = Mesh::CreateSphere(32, 16);
auto cube = Mesh::CreateCube();
```

## Modern C++23 Features Used

- **Concepts**: Type-safe templates with compile-time validation
- **Ranges**: Modern iteration and algorithm composition  
- **std::expected**: Proper error handling without exceptions
- **Modules**: Import std for faster compilation (where supported)
- **Spaceship Operator**: Automatic comparison operators
- **Designated Initializers**: Clean struct initialization
- **[[nodiscard]]**: Preventing accidental value discarding
- **constexpr**: Compile-time computation
- **RAII**: Automatic resource management

## Performance Features

- **Uniform Buffer Objects**: Efficient uniform data transfer
- **Instanced Rendering**: Draw many objects with one call  
- **Frustum Culling**: Only render visible objects
- **Hot Reloading**: Live shader and asset reloading
- **Memory Pools**: Reduced allocation overhead
- **Cache-Friendly Design**: Data structures optimized for CPU cache

## AI God Mode

Let Claude play god in the world. The engine exposes a JSON HTTP API on
`localhost:9090`; `ai_god.py` wires Claude up to it via tool-use and lets the
model experiment autonomously — querying state, spawning geometry, moving
the camera, iterating on compositions.

```bash
pip install -r requirements.txt
export ANTHROPIC_API_KEY=sk-ant-...
./build/ModernEngine &
python ai_god.py
```

Useful flags: `--max-turns N`, `--port 9090`, `--prompt "build a solar system"`.

## Contributing

1. Ensure your compiler supports C++23
2. Follow the existing code style
3. Add tests for new features
4. Update documentation

## License

MIT License - See LICENSE file for details

## Acknowledgments

- OpenGL community for excellent documentation
- GLM for mathematics library
- GLFW for cross-platform window management
- C++ standardization committee for modern language features