Data Binding Overview

Unreal Data Binding Fundamentals

If you’re unfamiliar with Rive’s Data Binding feature, please see Data Binding to get an understanding of the fundamental concepts.

🔧 Data Binding Overview

The Rive Unreal Plugin integrates the Rive ViewModel architecture into Unreal Engine, enabling dynamic data-driven content and interaction. Through data binding, you can expose gameplay variables, user input, or UI state directly to your Rive animations using a declarative model.

🔩 Core Components

• URiveViewModel: Represents a Rive-defined schema with properties and instance templates.
• URiveViewModelInstance: Holds runtime values for a ViewModel. Wraps rive::ViewModelInstanceRuntime and provides typed property accessors.
• URiveViewModelInstanceValue: Base class for all runtime properties. Derived types include:
  • URiveViewModelInstanceBoolean
  • URiveViewModelInstanceNumber
  • URiveViewModelInstanceString
  • URiveViewModelInstanceColor
  • URiveViewModelInstanceEnum
  • URiveViewModelInstanceTrigger
  • Nested ViewModels: URiveViewModelInstance
• Binding Targets: Instances can be bound to:
  • URiveArtboard – sets the data context for a Rive artboard and it’s associated state machine.
  • FRiveStateMachine – synchronizes ViewModel data with state machine inputs and outputs and binds it to the state machine’s artboard.

🔄 Lifecycle

1. Load ViewModel via URiveFile:

   URiveViewModel* ViewModel = RiveFile->GetViewModelByName("MyData"); 
   

2. Create Instance:

   URiveViewModelInstance* Instance = ViewModel->CreateInstance(); 
   

3. Bind to Artboard:

   Artboard->SetViewModelInstance(Instance);
   

4. Interact with Properties (e.g. trigger a state or update text):

   Instance->SetStringPropertyValue("Username", "RiveUser");
   Instance->FireTriggerProperty("Login"); 
   

5. Respond to Changes:

   NameProperty->BindToValueChange(MyCallback); 
   

⚙️ Architecture Highlights

• Properties and ViewModel Instances expose typed getters/setters in both C++ and Blueprints.
• ViewModelInstances can contain nested ViewModel instances.
• Callbacks are tracked and invoked safely via HandleCallbacks() (called per-frame by URiveArtboard::AdvanceStateMachine()).