# Build Linux

*Last Updated on December 1, 2020*

Please read the [general build guide](BUILD.md) for information on dependencies required for all platforms. Only Linux specific instructions are found in this file.

You can use the [Vircadia Builder](https://github.com/vircadia/vircadia-builder) to build on Linux more easily. Alternatively, you can follow the manual steps below.

## Ubuntu 16.04/18.04 specific build guide
### Ubuntu 16.04 only
Add the following line to *.bash_profile*  
`export QT_QPA_FONTDIR=/usr/share/fonts/truetype/dejavu/`
### Ubuntu 18.04 server only
Add the universe repository:  
_(This is not enabled by default on the server edition)_
```bash
sudo add-apt-repository universe
sudo apt-get update
```
#### Install build tools:
-  First update the repositories:  
```bash
sudo apt-get update -y
sudo apt-get upgrade -y
```
-  git
```bash
sudo apt-get install git -y
```
Verify by git --version  
-  g++
```bash
sudo apt-get install g++ -y
```
Verify by g++ --version  
-  *Ubuntu 18.04* cmake
```bash
sudo apt-get install cmake -y
```
Verify by cmake --version  
- *Ubuntu 16.04* cmake  
```bash
wget https://cmake.org/files/v3.14/cmake-3.14.2-Linux-x86_64.sh
sudo sh cmake-3.14.2-Linux-x86_64.sh --prefix=/usr/local --exclude-subdir
```
#### Install build dependencies:
-  OpenSSL:
```bash
sudo apt-get install libssl-dev
```
Verify with `openssl version`  
- OpenGL:
```bash
sudo apt-get install libgl1-mesa-dev -y
sudo ln -s /usr/lib/x86_64-linux-gnu/libGL.so.346.35 /usr/lib/x86_64-linux-gnu/libGL.so.1.2.0
```
- Verify OpenGL:
  - First install mesa-utils with the command `sudo apt install mesa-utils -y`
  - Then run `glxinfo | grep "OpenGL version"`  
#### To compile interface in a server you must install:
```bash
sudo apt-get -y install libpulse0 libnss3 libnspr4 libfontconfig1 libxcursor1 libxcomposite1 libxtst6 libxslt1.1
```
-  Misc dependencies:
```bash
sudo apt-get install libasound2 libxmu-dev libxi-dev freeglut3-dev libasound2-dev libjack0 libjack-dev libxrandr-dev libudev-dev libssl-dev zlib1g-dev
```
-  Install Python 3 and required packages:
```bash
sudo apt-get install python python3 python3-distro
```
-  Install node, required to build the jsdoc documentation:
```bash
sudo apt-get install nodejs
```

### Get code and checkout the branch you need

Clone this repository:
```bash
git clone https://github.com/vircadia/vircadia.git
```

To compile a DEV version checkout the branch you need. To get a list of all tags:
```bash
git fetch -a
```

Then checkout the main branch with:
```bash
git checkout master
```

### Using a custom Qt build

Qt binaries are only provided for Ubuntu. In order to build on other distributions, a Qt5 install
needs to be provided by setting the `VIRCADIA_QT_PATH` environment variable to a directory containing
a Qt install.

### Using the system's Qt

The system's Qt can be used, if the development packages are installed, by setting the
`VIRCADIA_USE_SYSTEM_QT` environment variable. The minimum recommended version is Qt 5.15.2, which is
also the last version available in the Qt 5 branch. It is expected that Linux distributions will have
Qt 5.15.2 available for a long time.

### Compiling

Create the build directory:
```bash
cd vircadia
mkdir build
cd build
```

Prepare makefiles:
```bash
cmake ..
```

- If cmake fails with a vcpkg error - delete /tmp/hifi/vcpkg.  

Start compilation of the server and get a cup of coffee:
```bash
make domain-server assignment-client
```

To compile interface:
```bash
make interface
```

The commands above will compile with a single thread. If you have enough memory,
you can decrease your build time using the `-j` flag. Since most x64 CPUs
support two threads per core, this works out to CPU_COUNT*2. As an example, if
you have a 2 core machine, you could use:
```
make -j4 interface
```

In a server, it does not make sense to compile interface.

### Running the software

#### Domain server

Running domain server:
```bash
./domain-server/domain-server
```

#### Assignment clients

Running assignment client:
```bash
./assignment-client/assignment-client -n 6
```

#### Interface

Running interface:
```bash
./interface/interface
```

Go to localhost in the running interface.

#### Notes

If your goal is to set up a development environment, it is desirable to set the
directory that vcpkg builds into with the `HIFI_VCPKG_BASE` environment variable.
For example, you might set `HIFI_VCPKG_BASE` to `/home/$USER/vcpkg`.
By default, vcpkg will build in the system `/tmp` directory.

If build is intended for packaging or creation of AppImage, `VIRCADIA_CPU_ARCHITECTURE`
CMake variable needs to be set to architecture specific value.
It defaults to `-march=native -mtune=native`, which yields builds optimized for particular
machine, but builds will not work on machines lacking same CPU instructions.
For packaging and AppImage it is recommended to set it to different value, for example `-msse3`.
Setting `VIRCADIA_CPU_ARCHITECTURE` to empty string will use default compiler settings and yield
maximum compatibility.