Reacting to Animation State Changes

AnimationStateTest.cs

using UnityEngine;
using UniRx;
using UniRx.Triggers;
using System;

[RequireComponent(typeof(Animator))]
public class AnimationStateTest : MonoBehaviour {

    void Start () {

        var animator = GetComponent<Animator>();

        animator.OnEnterState("Base Layer.AState")
            .Subscribe(_ =>
                Debug.Log("Entered AState")
            ).AddTo(this);

        animator.OnEnterState("Base Layer.BState")
            .Subscribe(_ =>
                Debug.Log("Entered BState")
            ).AddTo(this);


        // User input to change state machine state
        // A
        int AHash = Animator.StringToHash("A");
        Observable.EveryUpdate()
            .Where(_ => Input.GetKeyDown(KeyCode.A))
            .Subscribe(_ =>
                animator.SetTrigger(AHash)
            ).AddTo(this);

        // B
        int BHash = Animator.StringToHash("B");
        Observable.EveryUpdate()
            .Where(_ => Input.GetKeyDown(KeyCode.B))
            .Subscribe(_ =>
                animator.SetTrigger(BHash)
            ).AddTo(this);
    }	
}

public static class AnimationExtensions {
    public static IObservable<ObservableStateMachineTrigger.OnStateInfo> OnEnterState( this Animator animator, string fullPath ) {
        // Listen for state machine changes
        var observableStateMachineTrigger = animator.GetBehaviour<ObservableStateMachineTrigger>();

        if( observableStateMachineTrigger == null ) {
            Debug.LogError("Missing ObservableStateMachineTrigger Behaviour", animator.gameObject);
            return Observable.Empty<ObservableStateMachineTrigger.OnStateInfo>();
        }

        int fullPathHash = Animator.StringToHash(fullPath);
        return observableStateMachineTrigger.OnStateEnterAsObservable()
            .Where( onStateInfo => onStateInfo.StateInfo.fullPathHash == fullPathHash);
    }
}