CARLA has developed a co-simulation feature with PTV-Vissim. This allows to distribute the tasks at will, and exploit the capabilities of each simulation in favour of the user.
* Buy a license for [__PTV-Vissim simulator__](https://www.ptvgroup.com/en/solutions/products/ptv-vissim/). It is necessary to acquire the Driving Simulator Interface add-on.
* In the PTV-Vissim installation folder, look for a `DrivingSimulatorProxy.dll`. Move it to `C:\Windows\System32`.
Once that is done, the PTV-Vissim environment has to be set to run the co-simulation.
Everything related with this feature can be found in `Co-Simulation/PTV-Vissim`. CARLA provides some examples that contain environments for __Town01__, and __Town03__.
To run a co-simulation, use the script `PTV-Vissim/run_synchronization.py`. This has one mandatory argument containing the PTV-Vissim environment, and some other optional arguments.
Both simulations will run in synchrony. The actions or events happening in one simulator will propagate to the other. So far, the feature only includes vehicle movement, and spawning. The spawning is limited due to PTV-Vissim types.
* If a vehicle is spawned in CARLA, and in PTV-Vissim the setting is `Vehicle type: car`, the vehicle spawned will be a car. No matter if it as a motorbike in CARLA. In the examples provided, the vehicle type is set to `car`.
* If a vehicle is spawned in PTV-Vissim, CARLA will use a vehicle of the same type. The dimensions and characteristics will be similar, but not exactly the same.
* __Activate the driving simulator__. Go to `Base Data/Network settings/Driving simulator` and enable the option.
* __Specify the vehicle and pedestrian types__. These are the types that will be used in PTV-Vissim to sync with the spawnings done in CARLA. By default are empty.
* __Export the environment as `.inpx`__. Create the environment, export it, and run the co-simulation with `run_synchronization.py`.
