There are several tools provided by the CARLA team that allow users to edit maps at will from the Unreal Editor. This tutorial introduces the most relevant tools, according to their purpose.
There is a series of blueprints in `Carla/Blueprints/LevelDesign` that are useful to add props aligned in one direction. All of them use a series of meshes, and a Bezier curve that establishes the path where the props are placed.
There are differences between them, that make them fit specific purposes. However, the all work the same way. Only the parametrization presents differences.
* __Initialize the series__. The blueprints need a __Static Mesh__ that will be repeated. Initially, only one element will appear, standing on the starting point of a Bezier curve with two nodes, beginning and ending.
* __Define the path__. Press __Alt__ over one of the nodes, to create a new one and modify the curve. A new mesh will appear on every node of the curve, and the space between nodes will be filled with elements __separated by a distance__ measure. Adjust the curve using the weights on every node.
* __Customize the pattern__. This is where the blueprints present differences between each other.
!!! Warning
New props will probably interfere with the mesh navigation. If necessary, rebuild that as explained [here](tuto_A_add_map.md#generate-pedestrian-navigation) after doing these changes.
### BP_RepSpline
The blueprint __BP_RepSpline__ adds __individual__ elements along the path defined by a Bezier curve. There are some specificic parameters that change the serialization.
*__Distance between__ — Set the distance between elements.
*__Offset rotation__ — Set a fixed rotation for the different axis.
*__Random rotation__ — Set a range of random rotations for the different axis.
*__Offset translation__ — Set a range of random locations along the different axis.
*__Max Number of Meshes__ — Set the maximum amount of elements that will be place between nodes of the curve.
*__World aligned ZY__ — If selected, the elements will be vertically aligned regarding the world axis.
The blueprint __BP_Spline__ adds __connected__ elements __strictly__ following the path defined by a Bezier curve. The mesh will be warped to fit the path created.
The blueprint __BP_Wall__ adds __connected__ elements along the path defined by a Bezier curve. The mesh will not be warped to fit the curve, but the nodes will be respected.
The power line that connects the pole meshes can be customized.
*__Choose the mesh__ that will be used as wire.
*__Edit the tension__ value. If `0`, the power lines will be staight. The bigger the value, the looser the connection.
*__Set the sockets__. Sockets are empty meshes that represent the connection points of the power line. A wire is created form socket to socket between poles. The amount of sockets can be changed inside the pole meshes.
The blueprint __BP_Procedural_Building__ in `Content/Carla/Blueprints/LevelDesign` creates a realistic building using key meshes that are repeated along the structure. For each of them, the user can provide an array of meshes that will be used at random for variety. The meshes are only created once, and the repetitions will be instances of the same to save up costs.
Blueprints can be used instead of meshes, to allow more variety and customization for the building. Blueprints can use behaviour trees to set illumination inside the building, change the materials used, and much more.
The key meshes will be updated everytime a change is made, and the building will disappear. Enable `Create automatically` or click on `Create Building` to see the new result.
For each of them, except the __Roof__, there is a mesh to fill the center of the floor, and a __Corner__ mesh that will be placed on the sides of the floor. The following picture represents the global structure.
*__Use full blocks__ — If selected, the structure of the building will use only one mesh per floor. No corners nor repetitions will appear in each floor.
*__Doors__ — Meshes that appear in the ground floor, right in front of the central meshes. The amount of dloors and their location can be set. `0` is the initial position, `1` the next base repetition, and so on.
*__Walls__ — Meshes that substitute one or more sides of the building. For example, a plane mesh can be used to paint one side of the building.
<divstyle="text-align: right"><i>On the left, a building with no cornes and one door. <br> On the right, a building with a wall applied to one side of the building. The wall is a texture with no fire escape.</i></div>
The weather can be easily customized by the users in CARLA using the PythonAPI. However, there is some configuration that users can do in order to set the default weather for a map. The weather parameters available for configuration by the following blueprints, are the same accessible from the API. These are described [here](https://carla.readthedocs.io/en/latest/python_api/#carlaweatherparameters).
### BP_Weather
This blueprint is loaded into the world when the simulation starts. It contains the default weather parameters for every map, and these can be modified at will.
__1. Open the BP_Weather__ in `Content/Carla/Blueprints/Weather`.
__2. Go to the Weather group__ in the blueprint.
__3. Choose the desired town__ and modify the parameters.
This blueprint groups all the weather parameters. It can be loaded into the scene when there is no CARLA server running, and used to ea test different configurations before setting a new default weather.
