Installation and Setup

1. Follow the instructions in CARLA's documentation to install the Unreal 4 Engine (version 4.18) and build the CARLA project from the source for Linux.
   • Make certain CARLA and all its dependencies work before proceeding.
2. Install VictoryPlugin for UE4. For more information on Plugins and their installation, look here.
3. Merge the Trolley Mod into the CARLA project folder; it contains modified CARLA assets that must replace the local assets with the same name for the Trolley Mod to work. If the user cloned the CARLA repository into a directory named UnrealEngine_4.18 as outlined in the CARLA documentation, then the Trolley Mod files should be placed in .../UnrealEngine_4.18/carla/Unreal/CarlaUE4.
4. Make certain that the Trolley Mod replaces assets of the same name in the CARLA project. Don't be afraid of losing CARLA's original functionality; the Trolley Mod only adds data properties to existing CARLA Actors and adds some Actors of its own.
5. Enable Blutilities to be run on the UE4. After opening the CarlaUE4 project in the Editor, click the "Edit" tab in the top left of the viewport, and then click "Editor Preferences..." Under the "Experimental" section, check the box beside "Editor Utility Blueprints (Blutility)."
6. Set the boolean variables bSpawnWalkers in WalkerSpawnerBase.h and bSpawnVehicles in VehicleSpawnerBase.h to false; this prevents unwanted Actors from spawning into the level. Afterwards, recompile the CARLA project (look here for instructions to do so).
7. Optional: remove CARLA's default HUD. This displays a line of text along the screen when the simulation is running, which can break immersion. There are two ways to do this:
   • The most direct way is pressing the "G" key when the simulation is running. However, this must be done every time.
   • A more permanent solution is modifying the GameMode. With the project open in the Editor, click on the Blueprints button, navigate to the "GameMode: Edit CarlaGameMode" dropdown menu and change the HUD class to "HUD."
8. Optional: remove any unneeded control bindings. To do so, click on the Settings button in the Editor and click on the "Input" tab under the "Engine" section. From here, you can remove any key bindings that are considered detrimental to the operation of the experiment.
9. Congratulations! The Trolley Mod is now ready to run.

Important note: set the boolean variables bSpawnWalkers in WalkerSpawnerBase.h and bSpawnVehicles in VehicleSpawnerBase.h to true if you wish to use CARLA's native spawning scripts later.