Sample Tutorial: Cavrnus Car - Unreal

Game Engine	Unreal Engine 5.0
Tutorial Level	Easy
Properties	Sync Material Sync Color Sync String Sync Boolean
Project Files	https://github.com/Cavrnus-Inc/car-configurator-csc-unreal

Installing the Cavrnus Plugin (Unreal Engine)

The Cavrnus Spatial Connector plugin for Unreal has already been installed in this project. For guidance on how to add the CSC-Unreal plugin for your new projects, or to upgrade your plugin to a newer version, see the documentation under “Cavrnus for Administrators”.

This project comes pre-installed with the Cavrnus Spatial Connector plugin enabled. The next steps will connect a specific map in the project to a Cavrnus server.

Testing the Demo

To get an idea of what this demonstration will do, load the preconfigured map called “Cavrnized_CarConfigurator”.

In the Content Browser, under Content/Maps, double-click the “Cavrnized_CarConfigurator” level.
In the outliner, scroll down to the “Cavrnus” folder and click the CavrnusSpatialConnector actor.
In the Details panel, configure the settings for the CavrnusSpatialConnector on the Details panel:
1. Domain Name: cav.dev.cavrn.us
2. Auth Method: Guest Join Auto
3. Guest Join Username: <Enter any name here>
4. Space Join Method: Automatic
5. Automatic Space Join ID: Reference a valid 24-character Space ID from the /wiki/spaces/IKB/pages/815269529. (NOTE: Refer to the documentation on how to create a new Space and retrieve the Space ID).

Click the Play-In-Editor (PIE) button to run the level. (or press Alt-P)
Once the Space is connected, you can click any color button to change the color of the car.
Click the “Stop Simulation” button to stop PIE. (or press the Escape key).
Click the PIE button again to start the simulation.
1. Note that when the Space loads, the car will return to the last color you selected the last time you were loaded into the Space.

The Cavrnus Spatial Connector not only allows you to collaboratively edit scene with remote coworkers, but your changes will persist even after all users have left the Space.

In the next steps, we will connect a new map to a Cavrnus server.

Initial Cavrnus Setup

In the Content Browser, under the “Maps” folder, open the CarConfigurateScene level.
Add the CavrnusSpatialConnector instance to the level from the Cavrnus menu on the Unreal Editor Menu bar.
1. Note that you only need one instance of CavrnusSpatialConnector for a given level.

As described in the Setup Your Scene guide, configure the settings for the CavrnusSpatialConnector on the Details panel:
1. Domain Name: cav.dev.cavrn.us
2. Auth Method: Guest Join Auto
3. Guest Join Username: <Enter any name here>
4. Space Join Method: Automatic
5. Automatic Space Join ID: Reference a valid 24-character Space ID from the /wiki/spaces/IKB/pages/815269529. (NOTE: Refer to the documentation on how to create a new Space and retrieve the Space ID).

At this point, the level is now connected to a server and will directly enter a Space with copresence. The next step adds synchronization of level assets.

Verify Heads Up Display (HUD) Class

This project uses a custom game mode BP_CarConfigGM.
1. From the World Settings panel, expand the Game Mode rollout.
2. In the “GameMode Override” field, note the entry says “BP_CarConfigGM”.
This project also uses a custom HUD Class “BP_HUD_CarConfig” that references a custom Widget Blueprint : WB_CarConfig.

Setup the Synchronization workflow

The synchronization of the car color takes place in 3 steps.

Step 1: Update the Journal with a string value that describes the car color selected.

Step 2: Use the Cavrnus SyncMaterial component to update the car material with a texture corresponding to the color in the Journal.

Step 3: Create a texture map that will serve as a reference between the name (string) value of the color in Step 1 with the texture reference in Step 2.

In the Content Browser, under Content/Widgets, open the Widget Blueprint “WB_CarConfig”.
Click the “Graph” button on the top right of the Widget Blueprint Editor.
1. Note that Event stubs have already been placed for this Blueprint.

Before we can post string properties to a space, we first have to confirm that the space has been connected.

From the Execution Pin of the Event Construct node, attach the function Await Any Space Connection.
1. This dispatcher is part of the Cavrnus Function Library
Bind a custom Event to the “On Connected” pin of the Await Any Space Connection node.
1. Give this a logical name, such as “SetCurrentSpaceConnection”.
Right-click the “Space Connection” pin in SetCurrentSpaceConnection and select “Promote to Variable”.
1. Give the variable a logical name, such as “SpaceConnection”.
From the list of Variables under “My Blueprint”, drag the “Connected?” boolean variable and drop it on the execution pin of the Set Space Connection node.
1. This will add a Set node for that variable.
2. Check the box in the Set Connected? node to set it to true.

Now that the connection to a Space is confirmed, let’s set the behavior for the HUD buttons.

For each On Clicked event for the 5 button colors, connect a Post String Property Update node to the “True” pin of the branch node.
1. Space Connection: Drag the “SpaceConnection” variable onto this pin to connect it as a get node.
2. Container Name: Car
3. Property Name: CarColor
4. Property Value: Reference the “Property Value” in the table below

Button Color	Property Value	Texture File Name
White	car-color-white	car-color-white.png
Black	car-color-black	car-color-black.png
Red	car-color-red	car-color-red.png
Blue	car-color-blue	car-color-blue.png
Yellow	car-color-yellow	car-color-yellow.png

Step 1 is complete. Now let’s use the SyncMaterial component to update the car paint.

Navigate to the “Cavrnus” folder in the Outliner and open the BP_CarController in the Blueprint editor.
The BeginPlay event for this Blueprint is already setup to create a dynamic material instance (MID) and assign it to all of the painted surfaces of the car.
1. We’re going to insert a synchronization step into this blueprint.

In the Components panel, add a SyncMaterial component and CavrnusPropertiesContainer component.
1. In the CavrnusPropertiesContainer component, set the Container field to “Car”.
In the gap between Create Dynamic Material Instance and Get All Actors of Class with Tag, insert a Set Material Instance node.
1. Connect the “Return Value” of Create Dynamic Material Instance to the “New Material Instance” of the Set Material Instance node.
2. Drag the SyncMaterial component from the Components panel onto the “Target” pin for this node to attach a Get node.
From the Get SyncMaterial node above, create a Get Children Components node.
1. This will return an array of Material Sync components that SyncMaterial references.
2. To see this list, select SyncMaterial from the Components panel, and then expand the “Material Sync Map” rollout in the Details panel. Each of these Map elements is synchronized at runtime.
Insert a For Each Loop after Set Material Instance.
1. This will loop through each item in the Material Sync Map.
Insert a Cast to SyncMaterialTextureParam node after the For Each Loop.
1. The SyncMaterialTextureParam component will synchronize the texture we want to swap in the paint material.
From the “As Sync Material Texture Param” pin, drag a setter for the TextureMap variable.
1. This variable is a dictionary that stores mapping between texture names and corresponding texture references.
Promote the TextureMap pin to a variable and give it a logical name, such as “CarTextureMap”.

With Step 2 complete, all that remains is to define the Texture-Property map as described in the table above.

Select the CarTextureMap variable in the Variables panel.
In the details panel, under “Default Value”, add an element for each button in the HUD, corresponding to car paint colors.
1. Click the plus sign to add a map element to the Car Texture Map.
2. Name the element based on the Property Value in the table above.
3. Select the corresponding Texture File Name as described in the table above.
4. Repeat this for each item in the table.

And that’s it! The project is now fully connected to the Cavrnus server, with shared string properties that translate to texture swaps in the car material.

It’s worth noting that if you have matching projects in Unity and/or Unreal where the texture/property maps match (case-sensitive!), then running the applications in the same Space will synchronize in real-time!

Setting Up Copresence

Copresence in the scene requires a little setup for your Avatars. Fortunately, you can get started very quickly by using existing Character blueprints in the CSC plugin.

In the Details panel, under “Game Mode”, expand the “Selected GameMode” rollout.
Set the “Default Pawn Class” to BP_DesktopFlyModePawn.
1. Any Cavrnized character blueprint will work. This one is configured for desktops and moves in all directions.
Confirm that all inputs have been defined for your project.
For more information about setting up avatars for copresence using the CSC plugin, see the Avatar Documentation.

Final Product

With the Sync Material component added, not only can you synchronize the texture references, scalar and vector parameter in materials can be shared as well! Opacity, roughness, emissivity, any property that can be referenced as a data point or string value can be shared in real-time and stored in a persistent Space!