This guide details how to build CARLA from source on Windows. 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://forum.carla.org/c/installation-issues/linux) to post any queries you may have.
In this section you will find details of system requirements, minor and major software installations and Python dependencies that are required before you can begin to build CARLA.
* __165 GB disk space.__ CARLA itself will take around 32 GB and the related major software installations (including Unreal Engine) will take around 133 GB.
* __An adequate GPU.__ CARLA aims for realistic simulations, so the server needs at least a 6 GB GPU though we would recommend 8 GB. 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.
* [__Python3 x64__](https://www.python.org/downloads/) is the main scripting language in CARLA. Having a x32 version installed may cause conflict, so it is highly advisable to have it uninstalled.
Be sure that the above programs are added to the [environment path](https://www.java.com/en/download/help/path.xml). Remember that the path added should correspond to the progam's `bin` directory.
#### Python dependencies
Run the following command to install the dependencies for the Python API client:
Get the 2017 version of Visual Studio from [here](https://developerinsider.co/download-visual-studio-2017-web-installer-iso-community-professional-enterprise/). Choose __Community__ for the free version. Use the _Visual Studio Installer_ to install three additional elements:
* __Windows 8.1 SDK.__ Select it in the _Installation details_ section on the right or go to the _Indivdual Components_ tab and look under the _SDKs, libraries, and frameworks_ heading.
* __x64 Visual C++ Toolset.__ In the _Workloads_ section, choose __Desktop development with C++__. This will enable a x64 command prompt that will be used for the build. Check that it has been installed correctly by pressing the `Windows` button and searching for `x64`. Be careful __not to open a `x86_x64` prompt__.
* __.NET framework 4.6.2__. In the _Workloads_ section, choose __.NET desktop development__ and then in the _Installation details_ panel on the right, select `.NET Framework 4.6.2 development tools`. This is required to build Unreal Engine.
Other Visual Studio versions may cause conflict. Even if these have been uninstalled, some registers may persist. To completely clean Visual Studio from the computer, go to `Program Files (x86)\Microsoft Visual Studio\Installer\resources\app\layout` and run `.\InstallCleanup.exe -full`
From CARLA 0.9.11 onwards we have included fixes to Unreal Engine that require modification to the engine itself. This means that it is no longer possible to use the Unreal Engine version provided by Epic Games Launcher with CARLA and instead we need to build a modified version.
To build the modified version, follow the commands listed below to download the engine's code from source and apply the patches that we provide. Be aware that to download Unreal Engine's source code, __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.
Keep the Unreal Engine folder as close as `C:\\` as you can because if the path exceeds a certain length then `Setup.bat` will return errors in step 3.
1. Open the `UE4.sln` file inside the source folder with Visual Studio 2017.
2. In the build bar ensure that you have selected 'Development Editor', 'Win64' and 'UnrealBuildTool' options. Check [this guide](https://docs.unrealengine.com/en-US/ProductionPipelines/DevelopmentSetup/BuildingUnrealEngine/index.html) if you need any help.
3. In the solution explorer, right-click `UE4` and select `Build`.
5. Once the solution is compiled you can open the engine to check that everything was correct by launching the executable `Engine\Binaries\Win64\UE4Editor.exe`.
!!! Note
If the installation was successful, this should be recognised by Unreal Engine's version selector. You can check this by right-clicking on any `.uproject` file and selecting `Switch Unreal Engine version`. You should see a pop-up showing `Source Build at PATH` where PATH is the installation path that you have chosen. If you can not see this selector or the `Generate Visual Studio project files` when you right-click on `.uproject` files, something went wrong with the Unreal Engine installation and you will likely need to reinstall it correctly.
The button above will take you to the official repository of the project. Either download from there and extract it or clone it using the following command:
The `master` branch contains the latest fixes and features. Stable code is in the `stable` branch and previous CARLA versions have their own branch. Always remember to check the current branch in git with the command `git branch`.
Download the __latest__ assets to work with the current version of CARLA:
1. From the root CARLA directory, navigate to `\Util\ContentVersions.txt`. This document contains the links to the assets for all CARLA releases.
2. Extract the assets in `Unreal\CarlaUE4\Content\Carla`. If the path doesn't exist, create it.
3. Extract the file with a command similar to the following:
tar -xvzf <assets_file_name>.tar.gz.tar -C C:\path\to\carla\Unreal\CarlaUE4\Content\Carla
### Set Unreal Engine environment variable
It is necessary to set an environment variable so that CARLA can find the Unreal Engine installation folder. This allows users to choose which specific version of Unreal Engine is to be used. If no environment variable is specified, then CARLA will search for Unreal Engine in the windows registry and use the first version it finds there.
To set the environment variable:
1. Open Windows Control Panel and go to `Advanced System Settings` or search for `Advanced System Settings` in the Windows search bar.
2. On the `Advanced` panel open `Environment Variables...`.
3. Click `New...` to create the variable.
4. Name the variable `UE4_ROOT` and choose the path to the installation folder of the desired UE4 installation.
- All commands should be run in the root CARLA folder.
- Commands should be executed via the __x64 Native Tools Command Prompt for VS 2017__. Open this by clicking the `Windows` key and searching for `x64`.
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.
__Note that when the compilation is done, you may see a successful output in the terminal even if the compilation of the Python API client was unsuccessful.__ Check for any errors in the terminal output and check that a `.egg` file exists in `PythonAPI\carla\dist`. If you come across any errors, check the [F.A.Q.](build_faq.md) or post in the [CARLA forum](https://forum.carla.org/c/installation-issues/linux).
The following command compiles and launches Unreal Engine. Run this command each time you want to launch the server or use the Unreal Engine editor:
make launch
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:
# Terminal A
cd PythonAPI\examples
pip install -r requirements.txt
python3 spawn_npc.py
# Terminal B
cd PythonAPI\examples
python3 dynamic_weather.py
!!! Note
If you encounter the error `ModuleNotFoundError: No module named 'carla'` while running a script, you may be running a different version of Python than the one used to install the client. Go to `PythonAPI\carla\dist` and check the version of Python used in the `.egg` file.
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`.
Read the **[F.A.Q.](build_faq.md)** page or post in the [CARLA forum](https://forum.carla.org/c/installation-issues/linux) for any issues regarding this guide.
