servicepoint-tanks

Building and running

With Nix

Using the power of nix, you can just nix run git+https://git.berlin.ccc.de/vinzenz/servicepoint-tanks!

To build from local source:

# no submodules required
git clone https://github.com/kaesaecracker/servicepoint-tanks.git
cd servicepoint-tanks
nix build .#
result/bin/TanksServer

You can also use the provided devShells (nix develop .#) and follow the manual steps.

For proper IDE suggestions, you may need to initialize the submodules. They are not used for building by Nix though.

The hard way

# initialize the submodules
git clone https://github.com/kaesaecracker/servicepoint-tanks.git
cd servicepoint-tanks
git submodule update --init --recursive

# build
cd tank-frontent
npm install
npm run build
cd ../tanks-backend
dotnet build

The Docker builds are currently broken and need some updates for the new library repo structure.

Backend

• Uses the C# bindings from the servicepoint library for communication with the display.
• Stack: .NET / C# / ASP.NET / AOT-compiled
• Both traditional JSON over HTTP APIs and real-time WebSocket communication
• runs all game logic
• sends image and text to the service point display
• sends image to clients
• The game has a dynamic update rate. Hundreds of updates per second on a laptop are expected.
• One frame is ~7KB, not including the text and player specific data
• maps can be loaded from png files containing black and white pixels or simple text files
• some values (like tank speed) can be configured but are fixed at run time
• By default, the backend also hosts the frontend

Frontend

• Stack: React / Vite / TypeScript / plain CSS
• There is no server component dedicated to the frontend, everything is a single page after build
• Shows map rendered on server by setting canvas image data
• Sends user input to server
• real time communication via WebSockets, HTTP for the REST

Binary formats

Controls WebSocket

• Client sends 2 byte messages.
  • on or off: 0x01 or 0x02
  • input: Forward=0x01, Backward=0x02, Left=0x03, Right=0x04, Shoot=0x05
• The server never sends any messages.

Observer screen WebSocket

• same image for all clients
• server sends same format as for the service point display
• client responds with empty message to request the next frame

Player screen WebSocket

• image is rendered per player
• server sends same message as the observer WebSocket, but includes an additional 4 bits per set bit in the observer payload
  • first bit: belongs to current player
  • second bit: (reserved)
  • third and fourth bit: type of something
    • 00: wall
    • 01: tank
    • 10: bullet
    • 11: (reserved)
• client responds with empty message to request the next frame