差乘 点乘的利用

///
///
///

using UnityEngine;
using System;
using System.Collections;

[RequireComponent(typeof(Animator))]

//Name of class must be name of file as well

public class RandomCharacters : MonoBehaviour {

public float AvatarRange = 25;protected Animator avatar;private float SpeedDampTime = .25f; private float DirectionDampTime = .25f; //设定目标位置private Vector3 TargetPosition = new Vector3(0,0,0);// Use this for initializationvoid Start () {    //获得动画组件    avatar = GetComponent<Animator>();}void Update () {    //判断是否为空    if(avatar)    {        int rand = UnityEngine.Random.Range(0, 50);        //用随机数来切换动画        avatar.SetBool("Jump", rand == 20);        avatar.SetBool("Dive", rand == 30);        //判断两个3为向量的距离        if(Vector3.Distance(TargetPosition,avatar.rootPosition) > 5)        {     //缓慢切换动画，            avatar.SetFloat("Speed",1,SpeedDampTime, Time.deltaTime);            //获得动作系统正前方   根旋转 动画的旋转角度*正前方            Vector3 curentDir = avatar.rootRotation * Vector3.forward;             //朝向目标位置的方向        //目标位置减去动画根位置然后进去归一化//得到朝向目标位置的方向            Vector3 wantedDir = (TargetPosition - avatar.rootPosition).normalized;               //通过点乘来判断动画正前方 和目标位置的方向是否一样               //大于0表示方向接近差不多，等于1表示完全一直，               //小于0表示方向不一样，            if(Vector3.Dot(curentDir,wantedDir) > 0)            {                                                      //通过差乘结果来改变方向值越小 越慢                avatar.SetFloat("Direction",Vector3.Cross(curentDir,wantedDir).y,DirectionDampTime, Time.deltaTime);            }            else            {                                                                     //通过差乘结果来改变方向，方向差得越多就转得越快                avatar.SetFloat("Direction", Vector3.Cross(curentDir,wantedDir).y > 0 ? 1 : -1, DirectionDampTime, Time.deltaTime);            }        }        else        {            avatar.SetFloat("Speed",0,SpeedDampTime, Time.deltaTime);            if(avatar.GetFloat("Speed") < 0.01f)            {                TargetPosition = new Vector3(UnityEngine.Random.Range(-AvatarRange,AvatarRange),0,UnityEngine.Random.Range(-AvatarRange,AvatarRange));            }        }    }       }             

}