MMO Game

A multiplayer online game built with C++20 featuring a client-server architecture, 3D rendering, and physics simulation.

Features

• 3D rendering with SDL3 GPU API (terrain, grass, effects, UI, skybox)
• Entity Component System architecture using EnTT
• Physics simulation with Jolt Physics
• glTF model loading for characters, buildings, and environment
• HLSL shaders compiled to SPIR-V at build time via SDL_shadercross
• AI and combat systems
• Client-side interpolation for smooth networked movement
• Text rendering with SDL3_ttf
• Gamepad/controller support
• JSON-driven game data configuration (classes, monsters, world, etc.)

Dependencies

Dependencies are managed via CMake FetchContent (automatically downloaded):

• EnTT v3.14.0 (ECS)
• Jolt Physics v5.2.0
• tinygltf v2.9.7
• Standalone Asio 1.30.2
• GLM 1.0.3
• nlohmann/json v3.11.3
• SDL_shadercross (HLSL to SPIR-V shader compilation)

System dependencies (used if available, otherwise automatically built from source):

• SDL3 >= 3.4.0
• SDL3_ttf >= 3.2.2
• SDL3_image >= 3.4.0

Building

Install System Dependencies (Ubuntu/Debian)

# Optional - if not installed, these will be built from source automatically
sudo apt install libsdl3-dev libsdl3-ttf-dev libsdl3-image-dev

Build

mkdir build && cd build
cmake ..
make -j$(nproc)

Produces:

• build/src/server/mmo_server - Game server
• build/src/client/mmo_client - Game client

Running

# Start server (default port 7777)
./build/src/server/mmo_server [port]

# Start client
./build/src/client/mmo_client [-h host] [-p port]

Or use the convenience script:

./start.sh

Controls

Keyboard & Mouse

• WASD / Arrow Keys - Move (camera-relative)
• Right Mouse Button + Drag - Orbit camera
• Mouse Wheel - Zoom in/out
• Left Mouse Button / Space - Attack
• Shift - Sprint
• ESC - Menu

Gamepad

• Left Stick - Move
• Right Stick - Orbit camera
• Right Trigger - Attack
• Left Trigger - Sprint

Project Structure

mmo/
├── src/
│   ├── client/           # Client application
│   │   └── ecs/          # Client-side ECS components
│   ├── engine/           # Core engine (rendering, GPU, input)
│   │   ├── gpu/          # SDL3 GPU abstraction layer
│   │   ├── render/       # Rendering subsystems (terrain, grass, effects, UI)
│   │   ├── scene/        # Scene management
│   │   ├── shaders/      # HLSL shader sources
│   │   └── systems/      # Engine systems (camera)
│   ├── server/           # Server application
│   │   ├── ecs/          # Server-side ECS components
│   │   └── systems/      # Server-side ECS systems (AI, combat, movement, physics)
│   └── protocol/         # Shared networking protocol
├── assets/               # Game assets
│   ├── models/           # glTF models
│   └── textures/         # Texture files
├── data/                 # JSON game configuration
│   ├── classes.json      # Character class definitions
│   ├── monsters.json     # Monster definitions
│   ├── environment.json  # Environment settings
│   ├── server.json       # Server configuration
│   ├── town.json         # Town layout
│   └── world.json        # World settings
└── tools/                # Python utilities