一、动作控制：3、旋转与Quaternion类详解

1、Transform、rotation、eulerAngles关系

Transform里包含了rotation变量和eulerAngles
rotation里有包含了eulerAngles变量
使用示例：

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

public class QuaternionTest : MonoBehaviour
{
    public Transform A, B;
    public Quaternion rotation = Quaternion.identity;
    Vector3 eulerAngle = Vector3.zero;
    float speed = -10.0f;
    float tSpeed = 0.0f;
    // Use this for initialization
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {
        tSpeed += speed * Time.deltaTime;
        //第一种方式：将Quaternion实例对象赋值给transform的rotation
        rotation.eulerAngles = new Vector3(0.0f, tSpeed, 0.0f);
        A.rotation = rotation;
        //第二种方式：将三位向量代表的欧拉角直接赋值给transform的eulerAngle
        B.eulerAngles = new Vector3(0.0f, tSpeed, 0.0f);
    }
}

2、关键成员方法（1）LookRotation

public static Quaternion LookRotation(Vector3 forward);
public static Quaternion LookRotation(Vector3 forward, [DefaultValue("Vector3.up")] Vector3 upwards);

public class Quaternion_LookRotation_Test2 : MonoBehaviour
{
    public Transform target;
    void Update()
    {
        Vector3 relativePos = target.position - transform.position;
        Quaternion rotation = Quaternion.LookRotation(relativePos);
        transform.rotation = rotation;
    }
}

3、关键成员方法（2）RotateTowards

public static Quaternion RotateTowards(Quaternion from, Quaternion to, float maxDegreesDelta);
按步长匀速旋转到指定的旋转角度

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

public class Quaternion_RotateTowards_Test4 : MonoBehaviour
{
    public Transform target;
    public float speed;
    void Update()
    {
        float step = speed * Time.deltaTime;
        transform.rotation = Quaternion.RotateTowards(transform.rotation, target.rotation, step);
    }
}

3、关键成员方法（3）Lerp 和 Slerp

public class Quaternion_Lerp_Test3 : MonoBehaviour
{
    public enum RotateType
    {
        Lerp,
        Slerp
    }

    public RotateType type;
    public Transform from;
    public Transform to;
    public float speed = 0.1F;
    
    void Update()
    {
        //将自己的转向转到与to的方向一致
        if (type == RotateType.Lerp)
        {
            transform.rotation = Quaternion.Lerp(from.rotation, to.rotation, Time.time * speed);//（匀速）
        }
        else
            transform.rotation = Quaternion.Slerp(from.rotation, to.rotation, Time.time * speed);//（球型插值,最适合旋转）
    }
}

4、Quaternion对象与Vector3对象相乘

用于自身移动变换
transform.position += tansform.rotation * A;
其中A为Vector3的对象。transform对应的对象会沿着自身坐标系中向量A的方向移动A的模长的距离。transform.rotation与A相乘可以确定移动的方向和距离。