Unity的Animator动画系统-——StateMachineBehaviours，用来实现怪物的行为。

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前言

今天记录下unity的Animator中用到的StateMachineBehaviours这个API

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一、StateMachineBehaviours简介

从字面理解，就是状态机行为，官方的解释也都可以查的到，去查unity官方的API就可以了，说下自己的理解，
如图所示，只要继承了StateMachineBehaviours就可以直接使用Add Behaviour添加脚本了，这个抽象类里面有几个关于状态的虚方法，我们可以直接继承类然后去重写，感觉也应该是一整个动画系统的生命周期了，具体脚本这里贴一下

// Decompiled with JetBrains decompiler
// Type: UnityEngine.StateMachineBehaviour
// Assembly: UnityEngine.AnimationModule, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
// MVID: 049BE2AF-E36F-487E-B06E-F49D51A0BAB6
// Assembly location: C:\Program Files\Unity\Editor\Data\Managed\UnityEngine\UnityEngine.AnimationModule.dll

using UnityEngine.Animations;
using UnityEngine.Scripting;

namespace UnityEngine
{
    
  /// <summary>
  ///   <para>StateMachineBehaviour is a component that can be added to a state machine state. It's the base class every script on a state derives from.</para>
  /// </summary>
  [RequiredByNativeCode]
  public abstract class StateMachineBehaviour : ScriptableObject
  {
    
    public virtual void OnStateEnter(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex)
    {
    
    }

    public virtual void OnStateUpdate(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex)
    {
    
    }

    public virtual void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
    {
    
    }

    public virtual void OnStateMove(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
    {
    
    }

    public virtual void OnStateIK(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
    {
    
    }

    /// <summary>
    ///   <para>Called on the first Update frame when making a transition to a state machine. This is not called when making a transition into a state machine sub-state.</para>
    /// </summary>
    /// <param name="animator">The Animator playing this state machine.</param>
    /// <param name="stateMachinePathHash">The full path hash for this state machine.</param>
    public virtual void OnStateMachineEnter(Animator animator, int stateMachinePathHash)
    {
    
    }

    /// <summary>
    ///   <para>Called on the last Update frame when making a transition out of a StateMachine. This is not called when making a transition into a StateMachine sub-state.</para>
    /// </summary>
    /// <param name="animator">The Animator playing this state machine.</param>
    /// <param name="stateMachinePathHash">The full path hash for this state machine.</param>
    public virtual void OnStateMachineExit(Animator animator, int stateMachinePathHash)
    {
    
    }

    public virtual void OnStateEnter(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex,
      AnimatorControllerPlayable controller)
    {
    
    }

    public virtual void OnStateUpdate(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex,
      AnimatorControllerPlayable controller)
    {
    
    }

    public virtual void OnStateExit(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex,
      AnimatorControllerPlayable controller)
    {
    
    }

    public virtual void OnStateMove(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex,
      AnimatorControllerPlayable controller)
    {
    
    }

    public virtual void OnStateIK(
      Animator animator,
      AnimatorStateInfo stateInfo,
      int layerIndex,
      AnimatorControllerPlayable controller)
    {
    
    }

    public virtual void OnStateMachineEnter(
      Animator animator,
      int stateMachinePathHash,
      AnimatorControllerPlayable controller)
    {
    
    }

    public virtual void OnStateMachineExit(
      Animator animator,
      int stateMachinePathHash,
      AnimatorControllerPlayable controller)
    {
    
    }
  }
}

想详细的了解也可以直接代码里看。

二、用法举例

1.把要用到的虚方法封装一下

 public abstract class SealedSMB : StateMachineBehaviour
    {
    
        public sealed override void OnStateEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        public sealed override void OnStateUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        public sealed override void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }
    }

2.接下来就可以用到封装好的SealedSMB了，代码如下：

这里用到了泛型的约束必须是继承MonoBehaviour的

public class SceneLinkedSMB<TMonoBehaviour> : SealedSMB 
        where TMonoBehaviour : MonoBehaviour
    {
    
        protected TMonoBehaviour m_MonoBehaviour;
    
        bool m_FirstFrameHappened;
        bool m_LastFrameHappened;

        public static void Initialise (Animator animator, TMonoBehaviour monoBehaviour)
        {
    
            SceneLinkedSMB<TMonoBehaviour>[] sceneLinkedSMBs = animator.GetBehaviours<SceneLinkedSMB<TMonoBehaviour>>();

            for (int i = 0; i < sceneLinkedSMBs.Length; i++)
            {
    
                sceneLinkedSMBs[i].InternalInitialise(animator, monoBehaviour);
            }
        }

        protected void InternalInitialise (Animator animator, TMonoBehaviour monoBehaviour)
        {
    
            m_MonoBehaviour = monoBehaviour;
            OnStart (animator);
        }

        public sealed override void OnStateEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller)
        {
    
            m_FirstFrameHappened = false;

            OnSLStateEnter(animator, stateInfo, layerIndex);
            OnSLStateEnter (animator, stateInfo, layerIndex, controller);
        }

        public sealed override void OnStateUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller)
        {
    
            if(!animator.gameObject.activeSelf)
                return;
        
            if (animator.IsInTransition(layerIndex) && animator.GetNextAnimatorStateInfo(layerIndex).fullPathHash == stateInfo.fullPathHash)
            {
    
                OnSLTransitionToStateUpdate(animator, stateInfo, layerIndex);
                OnSLTransitionToStateUpdate(animator, stateInfo, layerIndex, controller);
            }

            if (!animator.IsInTransition(layerIndex) && m_FirstFrameHappened)
            {
    
                OnSLStateNoTransitionUpdate(animator, stateInfo, layerIndex);
                OnSLStateNoTransitionUpdate(animator, stateInfo, layerIndex, controller);
            }
        
            if (animator.IsInTransition(layerIndex) && !m_LastFrameHappened && m_FirstFrameHappened)
            {
    
                m_LastFrameHappened = true;
            
                OnSLStatePreExit(animator, stateInfo, layerIndex);
                OnSLStatePreExit(animator, stateInfo, layerIndex, controller);
            }

            if (!animator.IsInTransition(layerIndex) && !m_FirstFrameHappened)
            {
    
                m_FirstFrameHappened = true;

                OnSLStatePostEnter(animator, stateInfo, layerIndex);
                OnSLStatePostEnter(animator, stateInfo, layerIndex, controller);
            }

            if (animator.IsInTransition(layerIndex) && animator.GetCurrentAnimatorStateInfo(layerIndex).fullPathHash == stateInfo.fullPathHash)
            {
    
                OnSLTransitionFromStateUpdate(animator, stateInfo, layerIndex);
                OnSLTransitionFromStateUpdate(animator, stateInfo, layerIndex, controller);
            }
        }

        public sealed override void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller)
        {
    
            m_LastFrameHappened = false;

            OnSLStateExit(animator, stateInfo, layerIndex);
            OnSLStateExit(animator, stateInfo, layerIndex, controller);
        }

        /// <summary>
        /// Called by a MonoBehaviour in the scene during its Start function.
        /// </summary>
        public virtual void OnStart(Animator animator) {
     }

        /// <summary>
        /// Called before Updates when execution of the state first starts (on transition to the state).
        /// </summary>
        public virtual void OnSLStateEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }
    
        /// <summary>
        /// Called after OnSLStateEnter every frame during transition to the state.
        /// </summary>
        public virtual void OnSLTransitionToStateUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        /// <summary>
        /// Called on the first frame after the transition to the state has finished.
        /// </summary>
        public virtual void OnSLStatePostEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        /// <summary>
        /// Called every frame after PostEnter when the state is not being transitioned to or from.
        /// </summary>
        public virtual void OnSLStateNoTransitionUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        /// <summary>
        /// Called on the first frame after the transition from the state has started.  Note that if the transition has a duration of less than a frame, this will not be called.
        /// </summary>
        public virtual void OnSLStatePreExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        /// <summary>
        /// Called after OnSLStatePreExit every frame during transition to the state.
        /// </summary>
        public virtual void OnSLTransitionFromStateUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        /// <summary>
        /// Called after Updates when execution of the state first finshes (after transition from the state).
        /// </summary>
        public virtual void OnSLStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex) {
     }

        /// <summary>
        /// Called before Updates when execution of the state first starts (on transition to the state).
        /// </summary>
        public virtual void OnSLStateEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }

        /// <summary>
        /// Called after OnSLStateEnter every frame during transition to the state.
        /// </summary>
        public virtual void OnSLTransitionToStateUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }

        /// <summary>
        /// Called on the first frame after the transition to the state has finished.
        /// </summary>
        public virtual void OnSLStatePostEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }

        /// <summary>
        /// Called every frame when the state is not being transitioned to or from.
        /// </summary>
        public virtual void OnSLStateNoTransitionUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }

        /// <summary>
        /// Called on the first frame after the transition from the state has started.  Note that if the transition has a duration of less than a frame, this will not be called.
        /// </summary>
        public virtual void OnSLStatePreExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }

        /// <summary>
        /// Called after OnSLStatePreExit every frame during transition to the state.
        /// </summary>
        public virtual void OnSLTransitionFromStateUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }

        /// <summary>
        /// Called after Updates when execution of the state first finshes (after transition from the state).
        /// </summary>
        public virtual void OnSLStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex, AnimatorControllerPlayable controller) {
     }
    }

3.怪物具体的行为类

一会儿用的到

using Gamekit3D.Message;
using UnityEngine;

namespace Gamekit3D
{
    
    [DefaultExecutionOrder(100)]
    public class ChomperBehavior : MonoBehaviour, IMessageReceiver
    {
    
        public static readonly int hashInPursuit = Animator.StringToHash("InPursuit");
        public static readonly int hashAttack = Animator.StringToHash("Attack");
        public static readonly int hashHit = Animator.StringToHash("Hit");
        public static readonly int hashVerticalDot = Animator.StringToHash("VerticalHitDot");
        public static readonly int hashHorizontalDot = Animator.StringToHash("HorizontalHitDot");
        public static readonly int hashThrown = Animator.StringToHash("Thrown");
        public static readonly int hashGrounded = Animator.StringToHash("Grounded");
        public static readonly int hashVerticalVelocity = Animator.StringToHash("VerticalVelocity");
        public static readonly int hashSpotted = Animator.StringToHash("Spotted");
        public static readonly int hashNearBase = Animator.StringToHash("NearBase");

        public static readonly int hashIdleState = Animator.StringToHash("ChomperIdle");

        public EnemyController controller {
     get {
     return m_Controller; } }

        public PlayerController target {
     get {
     return m_Target; } }
        public TargetDistributor.TargetFollower followerData {
     get {
     return m_FollowerInstance; } }

        public Vector3 originalPosition {
     get; protected set; }
        [System.NonSerialized]
        public float attackDistance = 3;

        public MeleeWeapon meleeWeapon;
        public TargetScanner playerScanner;
        [Tooltip("Time in seconde before the Chomper stop pursuing the player when the player is out of sight")]
        public float timeToStopPursuit;

        [Header("Audio")]
        public RandomAudioPlayer attackAudio;
        public RandomAudioPlayer frontStepAudio;
        public RandomAudioPlayer backStepAudio;
        public RandomAudioPlayer hitAudio;
        public RandomAudioPlayer gruntAudio;
        public RandomAudioPlayer deathAudio;
        public RandomAudioPlayer spottedAudio;

        protected float m_TimerSinceLostTarget = 0.0f;

        protected PlayerController m_Target = null;
        protected EnemyController m_Controller;
        protected TargetDistributor.TargetFollower m_FollowerInstance = null;

        protected void OnEnable()
        {
    
            m_Controller = GetComponentInChildren<EnemyController>();

            originalPosition = transform.position;

            meleeWeapon.SetOwner(gameObject);

            m_Controller.animator.Play(hashIdleState, 0, Random.value);

            SceneLinkedSMB<ChomperBehavior>.Initialise(m_Controller.animator, this);
        }

        /// <summary>
        /// Called by animation events.
        /// </summary>
        /// <param name="frontFoot">Has a value of 1 when it's a front foot stepping and 0 when it's a back foot.</param>
        void PlayStep(int frontFoot)
        {
    
            if (frontStepAudio != null && frontFoot == 1)
                frontStepAudio.PlayRandomClip();
            else if (backStepAudio != null && frontFoot == 0)
                backStepAudio.PlayRandomClip ();
        }

        /// <summary>
        /// Called by animation events.
        /// </summary>
        public void Grunt ()
        {
    
            if (gruntAudio != null)
                gruntAudio.PlayRandomClip ();
        }

        public void Spotted()
        {
    
            if (spottedAudio != null)
                spottedAudio.PlayRandomClip();
        }

        protected void OnDisable()
        {
    
            if (m_FollowerInstance != null)
                m_FollowerInstance.distributor.UnregisterFollower(m_FollowerInstance);
        }

        private void FixedUpdate()
        {
    
            m_Controller.animator.SetBool(hashGrounded, controller.grounded);

            Vector3 toBase = originalPosition - transform.position;
            toBase.y = 0;

            m_Controller.animator.SetBool(hashNearBase, toBase.sqrMagnitude < 0.1 * 0.1f);
        }

        public void FindTarget()
        {
    
            //we ignore height difference if the target was already seen
            PlayerController target = playerScanner.Detect(transform, m_Target == null);

            if (m_Target == null)
            {
    
                //we just saw the player for the first time, pick an empty spot to target around them
                if (target != null)
                {
    
                    m_Controller.animator.SetTrigger(hashSpotted);
                    m_Target = target;
                    TargetDistributor distributor = target.GetComponentInChildren<TargetDistributor>();
                    if (distributor != null)
                        m_FollowerInstance = distributor.RegisterNewFollower();
                }
            }
            else
            {
    
                //we lost the target. But chomper have a special behaviour : they only loose the player scent if they move past their detection range
                //and they didn't see the player for a given time. Not if they move out of their detectionAngle. So we check that this is the case before removing the target
                if (target == null)
                {
    
                    m_TimerSinceLostTarget += Time.deltaTime;

                    if (m_TimerSinceLostTarget >= timeToStopPursuit)
                    {
    
                        Vector3 toTarget = m_Target.transform.position - transform.position;

                        if (toTarget.sqrMagnitude > playerScanner.detectionRadius * playerScanner.detectionRadius)
                        {
    
                            if (m_FollowerInstance != null)
                                m_FollowerInstance.distributor.UnregisterFollower(m_FollowerInstance);

                            //the target move out of range, reset the target
                            m_Target = null;
                        }
                    }
                }
                else
                {
    
                    if (target != m_Target)
                    {
    
                        if (m_FollowerInstance != null)
                            m_FollowerInstance.distributor.UnregisterFollower(m_FollowerInstance);

                        m_Target = target;

                        TargetDistributor distributor = target.GetComponentInChildren<TargetDistributor>();
                        if (distributor != null)
                            m_FollowerInstance = distributor.RegisterNewFollower();
                    }

                    m_TimerSinceLostTarget = 0.0f;
                }
            }
        }

        public void StartPursuit()
        {
    
            if (m_FollowerInstance != null)
            {
    
                m_FollowerInstance.requireSlot = true;
                RequestTargetPosition();
            }

            m_Controller.animator.SetBool(hashInPursuit, true);
        }

        public void StopPursuit()
        {
    
            if (m_FollowerInstance != null)
            {
    
                m_FollowerInstance.requireSlot = false;
            }

            m_Controller.animator.SetBool(hashInPursuit, false);
        }

        public void RequestTargetPosition()
        {
    
            Vector3 fromTarget = transform.position - m_Target.transform.position;
            fromTarget.y = 0;

            m_FollowerInstance.requiredPoint = m_Target.transform.position + fromTarget.normalized * attackDistance * 0.9f;
        }

        public void WalkBackToBase()
        {
    
            if (m_FollowerInstance != null)
                m_FollowerInstance.distributor.UnregisterFollower(m_FollowerInstance);
            m_Target = null;
            StopPursuit();
            m_Controller.SetTarget(originalPosition);
            m_Controller.SetFollowNavmeshAgent(true);
        }

        public void TriggerAttack()
        {
    
            m_Controller.animator.SetTrigger(hashAttack);
        }

        public void AttackBegin()
        {
    
            meleeWeapon.BeginAttack(false);
        }

        public void AttackEnd()
        {
    
            meleeWeapon.EndAttack();
        }

        public void OnReceiveMessage(Message.MessageType type, object sender, object msg)
        {
    
            switch (type)
            {
    
                case Message.MessageType.DEAD:
                    Death((Damageable.DamageMessage)msg);
                    break;
                case Message.MessageType.DAMAGED:
                    ApplyDamage((Damageable.DamageMessage)msg);
                    break;
                default:
                    break;
            }
        }

        public void Death(Damageable.DamageMessage msg)
        {
    
            Vector3 pushForce = transform.position - msg.damageSource;

            pushForce.y = 0;

            transform.forward = -pushForce.normalized;
            controller.AddForce(pushForce.normalized * 7.0f - Physics.gravity * 0.6f);

            controller.animator.SetTrigger(hashHit);
            controller.animator.SetTrigger(hashThrown);

            //We unparent the hit source, as it would destroy it with the gameobject when it get replaced by the ragdol otherwise
            deathAudio.transform.SetParent(null, true);
            deathAudio.PlayRandomClip();
            GameObject.Destroy(deathAudio, deathAudio.clip == null ? 0.0f : deathAudio.clip.length + 0.5f);
        }

        public void ApplyDamage(Damageable.DamageMessage msg)
        {
    
            //TODO : make that more generic, (e.g. move it to the MeleeWeapon code with a boolean to enable shaking of camera on hit?)
            if (msg.damager.name == "Staff")
                CameraShake.Shake(0.06f, 0.1f);

            float verticalDot = Vector3.Dot(Vector3.up, msg.direction);
            float horizontalDot = Vector3.Dot(transform.right, msg.direction);

            Vector3 pushForce = transform.position - msg.damageSource;

            pushForce.y = 0;

            transform.forward = -pushForce.normalized;
            controller.AddForce(pushForce.normalized * 5.5f, false);

            controller.animator.SetFloat(hashVerticalDot, verticalDot);
            controller.animator.SetFloat(hashHorizontalDot, horizontalDot);

            controller.animator.SetTrigger(hashHit);

            hitAudio.PlayRandomClip();
        }

#if UNITY_EDITOR
        private void OnDrawGizmosSelected()
        {
    
            playerScanner.EditorGizmo(transform);
        }
#endif
    }
}

4.ChomperSMBIdle类，去调用ChomperBehavior里的行为

ChomperSMBIdle类，主要是设定了一个时间范围，随机时间去触发怪物行为

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Animations;

namespace Gamekit3D
{
    
    public class ChomperSMBIdle : SceneLinkedSMB<ChomperBehavior>
    {
    
        public float minimumIdleGruntTime = 2.0f;
        public float maximumIdleGruntTime = 5.0f;

        protected float remainingToNextGrunt = 0.0f;

        public override void OnStateMachineEnter(Animator animator, int stateMachinePathHash)
        {
    
            if (minimumIdleGruntTime > maximumIdleGruntTime)
                minimumIdleGruntTime = maximumIdleGruntTime;

            remainingToNextGrunt = Random.Range(minimumIdleGruntTime, maximumIdleGruntTime);
        }

        public override void OnSLStateNoTransitionUpdate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
        {
    
            base.OnSLStateNoTransitionUpdate(animator, stateInfo, layerIndex);

            remainingToNextGrunt -= Time.deltaTime;

            if (remainingToNextGrunt < 0)
            {
    
                remainingToNextGrunt = Random.Range(minimumIdleGruntTime, maximumIdleGruntTime);
                m_MonoBehaviour.Grunt();
            }

            m_MonoBehaviour.FindTarget();
            if (m_MonoBehaviour.target != null)
            {
    
                m_MonoBehaviour.StartPursuit();
            }
        }
    }
}

---

总结

虽然代码比较多，但是思路还是蛮简单的，就是封装好StateMachineBehaviours，根据整个生命周期去触发对应的状态，具体执行放在了怪物的ChomperBehavior身上。今天就先说到这吧。
欢迎大佬多多来给萌新指正，欢迎大家来共同探讨。
如果各位看官觉得文章有点点帮助，跪求各位给点个“一键三连”，谢啦~

声明一下：本博文章若非特殊注明皆为原创原文链接
https://blog.csdn.net/Wrinkle2017/article/details/115697318
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