hullowheel-server

Server part of HulloWheel, a virtual gaming wheel for Android + Linux

Why?

I'm a lover of Euro Truck Simulator 2. I love overspeeding in it. Problems are:

1. I play on Linux (Ubuntu + Steam OS)
2. I don't have a physical joystick / game wheel
3. There were no virtual "wheel + gas pedal + brake" controller for Linux, although there is a great gamepad for both Linux and Windows written by rmst. But we drive trucks man, we want no yokes. Gas pedal and brake man!
4. Making my own game controller is cool.

What then?

I had the following inputs:

1. An Android phone
2. Inspiration from this repository by zvxryb
3. ETS2 (that was how I tested my wheel)

and the following output:

1. HulloWheel, a Android client + Linux server combination. See Hacking for details

Installing

There is a pre-built program available in the release page. It is only for 64-bit Linux though. If your system is not, you'll have to build the program yourself.

Once downloaded, there are no installation step. Just run it.

Running

./HulloWheel-x86_64 # Or only ./HulloWheel if you built it yourself

Also see the available options by:

./HulloWheel-x86_64 --help

Building

Dependencies

A list of libraries required:

# tools
cmake
make
gengetopt

# libraries + headers
zlib
pthread

On Ubuntu / Debian:

# With root privilege
apt-get install cmake make zlib1g zlib1g-dev libpthread-stubs0-dev gengetopt

I don't know other systems. Please make a PR to this README if you know. Thanks.

Build steps

# Install dependencies first
https://github.com/hulloanson/hullowheel-server.git
cd hullowheel-server
./build.sh

A binary named HulloWheel will appear at the root directory. Run it. Try it out with https://github.com/hulloanson/hullowheel-android

Run

./VWheel
# Press Ctrl-C / send SIGINT to stop it.

TODOs

Known issues

1. Now server normalizes client values. It shouldn't happen. Should leave it up to the client.

2. Performance. Now it lags behind a bit.

   Possible reasons:

   • Now each frame averages 29 bytes gzipped, which contains the state of all 24 buttons and 3 axes (wheel, gas, brake). Perhaps send only the modified inputs?

3. The only way to configure which port to listen to is to modify the code. Add argument support.

4. Have to restart server and android app after disconnects. Probably due to UDP intricacies I'm not familiar with.

   • Solved. Now the server auto-restarts on timeout

Hope-to-have Features

1. Runs on Windows
2. GUI

Try it with other games!

Now works with:

• Euro Truck Simulator 2
• jstest

Please add to this list if you find HulloWheel works with a game / software. Thanks.

Hacking

Overview of this server code

I tried to keep it clean and clever, but I so rarely touch C. Roast me all you want.

3 parts:

Main

Entrypoint. It:

• sets up a wheel called "HulloWheel" (uinput blablabla.); then
• starts a UDP server on port 20000 on a separate thread; and then
• listens for interrupts and tear down the wheel and server

Wheel

Everything about the wheel. Creating the wheel, registering on uinput, writing event input, etc. Exposes function emit that Server uses

Server

The listening socket part. The data decompressing part. The data parsing part. Also "emits" input events.

Also layout of a "frame":

0                  4                  8                  12                                                     36
|------------------|------------------|------------------|------------------------------------------------------|
|  wheel (float)   |  gas (float)     |  brake (float)   | buttons (byte) * 24                                  |
|------------------|------------------|------------------|------------------------------------------------------|

Note: all floats are 32-bit precision float, little endian

Misc

Logging

The HulloWheel server uses macrologger (courtesy to https://github.com/dmcrodrigues/macro-logger) for logging. Kinda simple I know, but I don't want a full-blown library with additional configurations files / (de-)initalizing lines. Educate me if there was more well-tested and simple ones.

Contributing

First a big thank you for your efforts. Please always make PRs on the dev branch.