eds-game-for-ftp-game-jam-2022

What is it? Not sure yet- looks like it's gonna be a bit like a multiplayer Asteroids.

Context

• FTP is the place I work
• One of the team members suggested a game jam
• I've been dying for an excuse to learn Rust

Approach

• Rust as programming language
• Bevy as game engine
• Rapier for physics
• WebAssembly as the runtime
• WebSockets as the network transport

Architecture

Roles

• Server
  • Runs an x86-built app in a Docker container
  • Uses xvfb to make Bevy okay with not having a display
  • Essentially runs the simulation (handles all the physics etc)
  • Consumes inputs from Clients at published rate
  • Publishes updates to Clients at ? Hz via WebSocket
• Client
  • Runs a WASM-built app in a web page
  • Publishes inputs to Server at ? Hz via WebSocket
  • Consumes updates from Server at published rate
  • Sets absolute transform, rotation and velocity of players on each update
  • Runs it's own physics simulation in between updates to provide convincing interpolation

Deployment

• xvfb container
  • Just provides a garbage bin to throw rendered frames into
• server container
  • Builds the x86 app and runs it, listening for WebSocket traffic on port 8080
• client container
  • Builds the WASM app, briefly runs it using wasm-server-runner so it can extract the static content
  • Serves up the static content using Nginx
• proxy container
  • Provides a single presence for the static content from the client and WebSocket in the server

TODO

Things I need to do:

• Reduce the network overhead
  • Send smaller messages / no messages when there are no changes
  • Don't send messages as frequently?
• Reduce the CPU overhead on the server
  • I think it's because I'm naively servicing the WebSocket at 60Hz when I could probably let it buffer for a bit longer

Things I want to do:

• Implement gamepad controls
• Implement controls for mobile somehow
• Add some scoring and other standard game stuff

Prerequisites (for macOS at least)

I basically the getting started page from the Bevy website.

• Rust
• zld

Quick start

If you have Docker and Docker Compose, you can simply run the following:

docker-compose up

Then open the game by navigating to https://127.0.0.1:1334.

Development

One-time

rustup target add wasm32-unknown-unknown
cargo install wasm-server-runner
cargo update

While iterating

I have a process that's something like this:

• Run the server natively (on my Mac)
• Run the client using wasm-server-runner
• Run the proxy container on it's own to provide the single presence
• Access http://127.0.0.1 to test my changes

So the commands up being something like:

# in shell 1
cargo build --target x86_64-apple-darwin --bin server --features server && target/x86_64-apple-darwin/debug/server

# in shell 2
export WASM_SERVER_RUNNER_ADDRESS=0.0.0.0; cargo build --target wasm32-unknown-unknown --bin client --features client && wasm-server-runner target/wasm32-unknown-unknown/debug/client.wasm

# in shell 3
cd proxy && ./build.sh && PROXY_PORT=80 ./deploy.sh