State Machines

Interact with the Rive State Machine in Unity.

For more information on Rive State Machines see the respective runtime and editor documentation.

State Machines

(Runtime) Rive's state machines provide a way to combine a set of animations and manage the transition between them through a series of inputs that can be programmatically controlled.

State Machine

(Editor) State Machines are a visual way to connect animations together and define the logic that drives the transitions.

Overview

A StateMachine contains Inputs and Events and advances (plays) an animation.

A Rive Widget automatically loads and advances the state machine from your artboard configuration settings. Here's how you can access the loaded state machine in your scripts:

[SerializeField] private RiveWidget m_riveWidget; 

void OnEnable()
{
    m_RiveWidget.OnWidgetStatusChanged += HandleWidgetStatusChanged;
}

private void HandleWidgetStatusChanged()
{
    if (m_RiveWidget.Status == WidgetStatus.Loaded)
    {
        // Do something with m_riveWidget.StateMachine
    }
}

void OnDisable()
{
    m_RiveWidget.OnWidgetStatusChanged -= HandleWidgetStatusChanged;
}

State Machines are instantiated from an Arboard instance:

private StateMachine m_stateMachine;

...

m_stateMachine = m_artboard?.StateMachine(); // default state machine
m_stateMachine = m_artboard?.StateMachine(0); // state machine at index
m_stateMachine = m_artboard?.StateMachine("Name"); // state machine with name

The state machine is played by calling advance and passing in the delta time:

private void Update()
{
    m_stateMachine?.Advance(Time.deltaTime);
}

Accessing Inputs

There are three input types, each extends SMIInput (State Machine Input):

SMIBool contains a .Value property, a boolean that can be set to true or false.
SMITrigger is a boolean that is set to true for one frame by calling the .Fire() method.
SMINumber contains a .Value property, a float that can be set to any value.

State machine inputs can be accessed in a number of different ways.

Access by name

Retrieve a state machine input by name and type.

Trigger:

SMITrigger someTrigger = m_stateMachine.GetTrigger("icon_02_press_trig");
if (someTrigger != null)
{
    someTrigger.Fire();
}

Bool:

SMIBool someBool = m_stateMachine.GetBool("centerHover");
if (someBool == null) return;
Debug.Log(someBool.Value);
someBool.Value = !someBool.Value;
Debug.Log(someBool.Value);

Number:

SMINumber someNumber = m_stateMachine.GetNumber("rating");
if (someNumber == null) return;
Debug.Log(someNumber.Value);
someNumber.Value = 4;
Debug.Log(someNumber.Value);

Access by index

Get the input count (length) and retrieve by index:

Debug.Log(m_stateMachine.InputCount());
SMIInput input = m_stateMachine.Input(1);

Access all inputs

Retrieve a list of all SMIInputs:

var inputs = m_riveStateMachine.Inputs();
foreach (var input in inputs)
{
    switch (input)
    {
        case SMITrigger smiTrigger:
        {
            // Do something
            break;
        }
        case SMIBool smiBool:
        {
            // Do something
            break;
        }
        case SMINumber smiNumber:
        {
            // Do something
            break;
        }
    }
}

Accessing Nested Inputs

For more information about accessing inputs in nested artboards, check out this example.

Additional Resources

For a complete example see the getting-started project in the examples repository and open the StateMachineInputScene scene. Enter Play mode and in the inspector on the Main Camera component, you can interact with all available state machine inputs for the provided animation.

Listeners

Rive Events