Similar to Blueprints, you can share user-created functions between asset graphs by making the function "public". Unlike Blueprints, which only share functions to child classes, Control Rig functions can be shared project-wide. You can create custom function libraries, and share them with all Control Rig graphs in your project.
This document provides a guide for the best practices for creating function libraries in Control Rig, and shows how you can access the default engine-provided function library.
New Function Library
The following steps will show you how to create and use a new Control Rig function library.
Create Control Rig Container
As custom functions can only exist inside Control Rig Assets, the first step will be to create a Control Rig Asset. This Control Rig should not be linked to any particular Skeletal Mesh, as it will be used primarily to contain your functions.
In the Content Browser, click Add (+), then select Animation > Control Rig. In the Create Control Rig Blueprint dialog window, select ControlRig and click Create. Open the Control Rig after it is created.
For the purposes of this asset, your function libraries are Control Rig Assets, and do not include dependencies on any particular skeleton. As a container of functions, this allows for the asset to be as lightweight as possible.
Create Public Function
In the Control Rig Editor, create a new function by clicking Add (+) on the Functions section of My Blueprint.
Next, select the function, and in the Details panel set Access Specifier to Public. This makes the function publicly accessible in all Control Rigs.
Setup Data in Function
From within your function, you can create any arbitrary contained logic you want, including metadata on the function such as tooltip descriptions and context menu categories.
In this example, For Each and Set Control Visibility nodes were created and connected to the function's Entry and Return nodes.
To create variable inputs on the Entry node, select Entry and click Add (+) on the Inputs category in the Details panel. In this example, the following variables were created:
- Rig Element Key, as an Array type.
- Boolean, as a Single type.
Next, connect the variable inputs to their corresponding nodes.
Optionally, you can also edit the Node Settings properties in the Details panel to add categorization, tooltip, or other helpful properties to the function.
| Name | Description |
|---|---|
| Category | Filling this property puts the node within the named context menu category. This category is visible when adding the node in the Control Rig graph.  |
| Keywords | Adds search terms you can use to find this function when searching for it using the context menu.  |
| Description | Adds a tooltip description for this function. You can view the tooltip when hovering your cursor either on the context menu item, or on the node after it is added to the graph.  |
| Color | Sets the color of the function node header. You can preview the look of your node by expanding the Node Defaults category.  |
Referencing the Function
To add your shared function in another Control Rig, right-click in the Rig Graph and add your function from the context menu. Shared functions also display their folder path in the node header for reference.
Double-clicking on a shared function node opens the Control Rig Asset containing the function, and the function logic.
Localizing Functions
In cases where you want to diverge the logic of the function from the shared version, you can localize the function, which creates a local copy of the function logic within your current Rig Graph.
To do this, right-click on the function node and select Localize Function. In the dialog window, ensure the function is enabled and click OK.
The function now converts to a local function, where you can diverge the logic locally.
Standard Function Library
By default, Unreal Engine contains a Control Rig Standard Function Library, which can be referenced to understand how to construct your own function libraries. Additionally, it contains a variety of functions that can be used to assist your own rigging workflows.
The Standard Function Library is located within the Control Rig Plugin folder. To access it, open the Content Browser and ensure the plugin folder is enabled by clicking Settings and enabling Show Engine Content and Show Plugin Content.
Next, navigate to and open StandardFunctionLibrary located in Engine > Plugins > Control Rig Content > StandardFunctionLibrary.
Once open, you can view the various functions in the My Blueprint panel.
Because the Standard Function Library is provided by Engine Content, any changes that you make in this asset will be overridden if you reinstall or update Unreal Engine. We reccomend instead to create your own Function Library and not modify the Engine Content one.