This guide details how to build CARLA from source on Linux. There are two parts. Part one details system requirements and installations of required software, and part two details how to actually build and run CARLA.
The build process is long (4 hours or more) and involves several kinds of software. It is highly recommended to read through the guide fully before starting.
If you come across errors or difficulties then have a look at the **[F.A.Q.](build_faq.md)** page which offers solutions for the most common complications. Alternatively, use the [CARLA forum](https://github.com/carla-simulator/carla/discussions) to post any queries you may have.
* __Ubuntu 18.04.__ CARLA provides support for previous Ubuntu versions up to 16.04. **However** proper compilers are needed for Unreal Engine to work properly. Dependencies for Ubuntu 18.04 and previous versions are listed separately below. Make sure to install the ones corresponding to your system.
* __130 GB disk space.__ Carla will take around 31 GB and Unreal Engine will take around 91 GB so have about 130 GB free to account for both of these plus additional minor software installations.
* __An adequate GPU.__ CARLA aims for realistic simulations, so the server needs at least a 6 GB GPU although 8 GB is recommended. A dedicated GPU is highly recommended for machine learning.
* __Two TCP ports and good internet connection.__ 2000 and 2001 by default. Make sure that these ports are not blocked by firewalls or any other applications.
__If you are upgrading from CARLA 0.9.12 to 0.9.13__: you must first upgrade the CARLA fork of the UE4 engine to the latest version. See the [__Unreal Engine__](#unreal-engine) section for details on upgrading UE4
CARLA requires many different kinds of software to run. Some are built during the CARLA build process itself, such as *Boost.Python*. Others are binaries that should be installed before starting the build (*cmake*, *clang*, different versions of *Python*, etc.). To install these requirements, run the following commands:
To avoid compatibility issues between Unreal Engine and the CARLA dependencies, use the same compiler version and C++ runtime library to compile everything. The CARLA team uses clang-8 (or clang-10 in Ubuntu 20.04) and LLVM's libc++. Change the default clang version to compile Unreal Engine and the CARLA dependencies.
Starting with CARLA 0.9.12, users have the option to install the CARLA Python API using `pip` or `pip3`. Version 20.3 or higher is required. To check if you have a suitable version, run the following command:
```sh
# For Python 3
pip3 -V
# For Python 2
pip -V
```
If you need to upgrade:
```sh
# For Python 3
pip3 install --upgrade pip
# For Python 2
pip install --upgrade pip
```
You must install the following Python dependencies:
Be aware that to download this fork of Unreal Engine, __you need to have a GitHub account linked to Unreal Engine's account__. If you don't have this set up, please follow [this guide](https://www.unrealengine.com/en-US/ue4-on-github) before going any further.
__1.__ Clone the content for CARLA's fork of Unreal Engine 4.26 to your local computer:
The button above will take you to the official repository of the project. Either download from there and extract it locally or clone it using the following command:
The `master` branch contains the current release of CARLA with the latest fixes and features. Previous CARLA versions are tagged with the version name. Always remember to check the current branch in git with the command `git branch`.
You will need to download the __latest__ assets to work with the current version of CARLA. We provide a script to automate this process. To use the script, run the following command in the CARLA root folder:
The Python API client grants control over the simulation. Compilation of the Python API client is required the first time you build CARLA and again after you perform any updates. After the client is compiled, you will be able to run scripts to interact with the simulation.
The following command compiles the Python API client:
The CARLA client library will be built in two distinct, mutually exclusive forms. This gives users the freedom to choose which form they prefer to run the CARLA client code. The two forms include `.egg` files and `.whl` files. Choose __one__ of the following options below to use the client library:
__A. `.egg` file__
>The `.egg` file does not need to be installed. All of CARLA's example scripts automatically [look for this file](build_system.md#versions-prior-to-0912) when importing CARLA.
>If you previously installed a CARLA `.whl`, the `.whl` will take precedence over an `.egg` file.
__B. `.whl` file__
>The `.whl` file should be installed using `pip` or `pip3`:
```sh
# Python 3
pip3 install <path/to/wheel>.whl
# Python 2
pip install <path/to/wheel>.whl
```
>This `.whl` file cannot be distributed as it is built specifically for your OS.
!!! Warning
Issues can arise through the use of different methods to install the CARLA client library and having different versions of CARLA on your system. It is recommended to use virtual environments when installing the `.whl` and to [uninstall](build_faq.md#how-do-i-uninstall-the-carla-client-library) any previously installed client libraries before installing new ones.
The project may ask to build other instances such as `UE4Editor-Carla.dll` the first time. Agree in order to open the project. During the first launch, the editor may show warnings regarding shaders and mesh distance fields. These take some time to be loaded and the map will not show properly until then.
__3.__ __Start the simulation__:
Press **Play** to start the server simulation. The camera can be moved with `WASD` keys and rotated by clicking the scene while moving the mouse around.
Test the simulator using the example scripts inside `PythonAPI\examples`. With the simulator running, open a new terminal for each script and run the following commands to spawn some life into the town and create a weather cycle:
If the simulation is running at a very low FPS rate, go to `Edit -> Editor preferences -> Performance` in the Unreal Engine editor and disable `Use less CPU when in background`.
### Other make commands
There are more `make` commands that you may find useful. Find them in the table below:
Read the **[F.A.Q.](build_faq.md)** page or post in the [CARLA forum](https://github.com/carla-simulator/carla/discussions) for any issues regarding this guide.
