4-17 Wandering NPCs

前一章我們完成了簡單的NPC系統，但是NPC在場景中亂跑，這樣的感覺很奇怪對吧？所以本章要教大家製作走路的NPC。

首先，請大家看看NPC使用的ThirdPersonAnimatorControl。

在Animator視窗點擊Grounded狀態。

從Inspector視窗會看見Motion的部分使用的Blend Tree，請點兩下開啟。

開啟後會看見如下圖的視窗，當紅點在中央下方時，角色的狀態是不會動的Idle狀態。

當紅點調整到最上面，就會發現角色開始跑起來了。

如果將紅點慢慢移到下方，角色的動作又會變得緩慢，像是在走路一樣。

所以，根據以上介紹的機制，透過調整Forward數值，可以控制角色的動作是偏向走路或者跑步。程式碼中在Character.cs中的UpdateAnimator方法，於forwardAmount中乘以一個參數，名為animatorForwardCap，這個參數會設為SerializeField。

修改後的Character.cs如下：

using System;
using UnityEngine;
using UnityEngine.AI;
using RPG.CameraUI;

namespace RPG.Character{
 [SelectionBase]
 public class Character : MonoBehaviour
 {
  [Header("Audio")]
  [Range(0.0f, 1.0f)][SerializeField] float spatialBlend = 1f;

  [Header("Capsule Collider")]
  [SerializeField] Vector3 colliderCenter = new Vector3(0, 1, 0);
  [SerializeField] float colliderRadius = 0.3f;
  [SerializeField] float colliderHeight = 1.5f;

  [Header("Animator")]
  [SerializeField] RuntimeAnimatorController animatorController;
  [SerializeField] AnimatorOverrideController animatorOverrideController;
  [SerializeField] Avatar avatar;
  [Range(0.0f, 1.0f)][SerializeField] float animatorForwardCap = 1f;

  [Header("Movement")]
  [SerializeField] float moveSpeedMultiplier = 1f;
  [SerializeField] float animationSpeedMultiplier = 1f;
  [SerializeField] float movingTurnSpeed = 1800;
  [SerializeField] float stationaryTurnSpeed = 1800;
  [SerializeField] float moveThreshold = 1f;

  [Header("Nav Mesh Agent")]
  [SerializeField] float steeringSpeed = 1.0f;

  NavMeshAgent navMeshAgent = null;
  Animator animator = null;
  Rigidbody myRigidbody = null;
  float turnAmount;
  float forwardAmount;
  bool isAlive = true;

  void Awake(){
   AddRequiredComponents ();
  }

  private void AddRequiredComponents(){
   CapsuleCollider capsuleCollider = gameObject.AddComponent ();
   capsuleCollider.center = colliderCenter;
   capsuleCollider.radius = colliderRadius;
   capsuleCollider.height = colliderHeight;

   myRigidbody = gameObject.AddComponent ();
   myRigidbody.collisionDetectionMode = CollisionDetectionMode.Continuous;
   myRigidbody.constraints = RigidbodyConstraints.FreezeRotation;

   AudioSource audioSource = gameObject.AddComponent ();
   audioSource.spatialBlend = spatialBlend;

   animator = gameObject.AddComponent ();
   animator.runtimeAnimatorController = animatorController;
   animator.avatar = avatar;

   navMeshAgent = gameObject.AddComponent ();
   navMeshAgent.updateRotation = false;
   navMeshAgent.updatePosition = true;
   navMeshAgent.speed = steeringSpeed;
  }

  void Update(){
   if (navMeshAgent.remainingDistance > navMeshAgent.stoppingDistance && isAlive) {
    Move(navMeshAgent.desiredVelocity);
   } else {
    Move (Vector3.zero);
   }
  }

  void Move(Vector3 movement)
  {
   SetForwardAndTurn (movement);
   ApplyExtraTurnRotation();
   UpdateAnimator();
  }

  public float GetAnimSpeedMultiplier(){
   return animator.speed;
  }

  public void Kill(){
   isAlive = false;
  }

  public void SetDestination(Vector3 worldPos){
   navMeshAgent.SetDestination(worldPos);
  }

  public void SetStopDistance(float stoppingDistance){
   navMeshAgent.stoppingDistance = stoppingDistance;
  }

  public AnimatorOverrideController GetOverrideController(){
   return animatorOverrideController;
  }

  private void SetForwardAndTurn(Vector3 movement){
   // 將Wolrd相對的向量轉換成Local相對的向量
   if (movement.magnitude > moveThreshold) {
    movement.Normalize ();
   }
   // 將Worldspace的方向轉換成LocalSpace
   Vector3 localMovement = transform.InverseTransformDirection(movement);
   turnAmount = Mathf.Atan2(localMovement.x, localMovement.z);
   forwardAmount = localMovement.z;
  }

  void UpdateAnimator()
  {
   // update the animator parameters
   animator.SetFloat("Forward", forwardAmount * animatorForwardCap, 0.1f, Time.deltaTime);
   animator.SetFloat("Turn", turnAmount, 0.1f, Time.deltaTime);
   animator.speed = animationSpeedMultiplier;
  }

  void ApplyExtraTurnRotation()
  {
   // help the character turn faster (this is in addition to root rotation in the animation)
   float turnSpeed = Mathf.Lerp(stationaryTurnSpeed, movingTurnSpeed, forwardAmount);
   transform.Rotate(0, turnAmount * turnSpeed * Time.deltaTime, 0);
  }

  void OnAnimatorMove(){
   if (Time.deltaTime > 0) {
    Vector3 velocity = (animator.deltaPosition * moveSpeedMultiplier) / Time.deltaTime;
    // 保持y軸的速度不變
    velocity.y = myRigidbody.velocity.y;
    myRigidbody.velocity = velocity;
   }
  }
 }
}

修改好程式碼後，大家可以參考下圖的參數進行Character的設定，我將Animator Forward Cpa設為0.3，Move Speed Multiplier設為0.3，Moving Turn Speed跟Stationary Turn Speed設為100。

 執行遊戲，NPC成功在巡邏點上緩慢地行走嘍！