Visual State Machine V2 (VSM2)

Overview

Currently still a work in progress and subject to breaking changes. Visual State Machine is a Unity package designed to simplify the creation and management of state machines in Unity projects. It provides a visual editor for designing state machines, making it easier to create complex behaviors without writing extensive code.

vsm2_3.mp4

Features

• Visual Editor: Design state machines using a user-friendly graphical interface.
• Unity Integration: Seamlessly integrates with Unity, allowing for easy implementation in your game projects.
• Custom State Support: Create your own states to handle specific game behaviors.
• Transition Management: Easily manage transitions between states with intuitive controls.

Installation

To install Visual State Machine in your Unity project, follow these steps:

1. Via package manager add a package from git url https://github.com/PaulNonatomic/VisualStateMachineV2.git

Usage

1. Create a state machine asset from the project panel. Right click -> Create -> State Machine -> State Machine
2. Either right click and select "Add State" or drag out from the Entry State

Usage.mp4

3. The State Selection window appears listing all available states.
   • States are grouped by namespace with the inbuilt states appearing at the top.
   • The group of states nearest to the location of the state machine asset will open by default but all states remain accessible.

4. Create a custom state. Here's the built in DelayState as an example.

• Add a Transition attribute to an exposed event Action in order for it to appear upon the states node in the State Machine Editor
• Serialized and public properties are also exposed in the states node in the State Machine Editor. Note fields should be populated with value types and assets and not scene types.

[NodeWidth(width:190), NodeColor(NodeColor.Teal), NodeIcon(NodeIcon.Clock)]
public class DelayState : BaseDelayState
{
    [Transition(frameDelay:0)]
    public event Action OnComplete;
    
    [NonSerialized]
    private float _elapsedTime;

    public override void OnEnterState()
    {
        _elapsedTime = 0f;
    }
    
    public override void OnUpdateState()
    {
        _elapsedTime += Time.deltaTime;

        if (_elapsedTime < Duration) return;
        OnComplete?.Invoke();
    }

    public override void OnExitState()
    {
        //...
    }
}

5. Create a game object with a StateMachineController component upon it and assign it your new state machine asset.
6. Run the application with the StateMachineController selected to see the state of your state machine within the State Machine Editor window.

Loops with Jump Nodes

Add JumpOutState state and set it's Id. Then create a JumpInState with the corresponding Id to jump from one node to another.

Looping.mp4

Transition Delay

The process of transitioning between nodes originally incurred no delay at all but when wiring up a looping state machine it could cause a stack overflow. To prevent this a delay of 1 frame has been added to all transitions by default, but this can be configured on a per transition bases by passing a frameDelay value through the Transition attribute, but please use with caution as a frameDelay of 0 can cause a stack overflow.

Copy & Paste

The State Machine Editor supports copy and paste within and between state machines.

CopyAndPaste.mp4

Shared Data

States have access to a shared data store

public class StateOne : State
{
    [Transition] public event Action OnComplete;

    public override void OnEnterState()
    {
        SharedData.SetData("age", 42);
        OnComplete?.Invoke();
    }

    public override void OnExitState()
    {
        //...
    }
}
    
public class StateTwo : State
{
    [Transition] public event Action OnComplete;
    
    public override void OnEnterState()
    {
        var age = SharedData.GetData<int>("age");
        Debug.Log($"StateTwo - Age:{age}");
        
        OnComplete?.Invoke();
    }

    public override void OnExitState()
    {
        //...
    }
}

This same data store is exposed externally to the state machine through the StateMachineController.SharedData

License

VisualStateMachineV2 is licensed under the MIT license