3D等距旋转相机场景下2D角色精灵动画方向适配实现

我正在尝试编写一套玩家精灵动画控制脚本，实现相机旋转时精灵动画方向自动调整的效果。当前项目为3D等距世界，每个朝向对应固定机位相机，场景中玩家为2D精灵，目前已独立编写玩家控制器、玩家动画、精灵渲染器三个脚本。

Player Controller（玩家控制器） #

该控制器基于相机朝向实现移动逻辑，适配项目中多相机对应不同朝向的设计，代码如下：

public class PlayerController : MonoBehaviour
{
    public float speed = 5f;
    
void Update()
    {
        var moveInput = new Vector3(Input.GetAxis("Horizontal"), 0f , Input.GetAxis("Vertical"));

        moveInput = Camera.main.transform.TransformDirection(moveInput);
        moveInput.y = 0;
        moveInput = moveInput.normalized;
    
        transform.position += moveInput * Time.deltaTime * speed;
    }
}

Player Animation（玩家动画） #

我参考的这套玩家动画脚本原本是为2D控制器编写的，逻辑清晰但无法直接适配当前3D场景，我需要明确如何正确添加行走动画逻辑，让脚本可以追踪玩家当前朝向，同步更新精灵渲染器的显示内容。现有代码如下：

public class PlayerAnimation : MonoBehaviour

{
    public Rigidbody2D body;
    public SpriteRenderer spriteRenderer;
    public List<Sprite> nSprite;
    public List<Sprite> neSprite;
    public List<Sprite> eSprite;
    public List<Sprite> seSprite;
    public List<Sprite> sSprite;
    public float frameRate;
    float idleTime;
    Vector3 direction;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        direction = new Vector3(Input.GetAxis("Horizontal"), 0f , Input.GetAxis("Vertical")).normalized;
        
        direction = Camera.main.transform.TransformDirection(direction);

        HandleSpriteFlip();

        List<Sprite> directionSprites = GetSpriteDirection();

        if(directionSprites != null) //holding direction
        {
            float playTime = Time.time - idleTime; //time since we sterted walking
            int totalFrames = (int)(playTime * frameRate); //total frames since we started
            int frame =  totalFrames % directionSprites.Count; //current frame

            spriteRenderer.sprite = directionSprites[frame];
        }
        else //holding nothing, input is neutral
        {
            idleTime = Time.time;
        }
    }

    void HandleSpriteFlip()
    {
        if (!spriteRenderer.flipX && direction.x < 0)
        {
            spriteRenderer.flipX = true;
        }
        else if (spriteRenderer.flipX && direction.x > 0)
        {
            spriteRenderer.flipX = false;
        }
    }

    List<Sprite> GetSpriteDirection()
    {

        List<Sprite> selectedSprites = null;

        if (direction.y > 0) //north
        {
            if (Mathf.Abs(direction.x) > 0) //east or west
            {
                selectedSprites = neSprite;
            }
            else {//neutral
                selectedSprites = nSprite;
            }
        }
        else if (direction.y < 0) //south
        {
            if (Mathf.Abs(direction.x) > 0) //east or west
            {
                selectedSprites = seSprite;
            }
            else {//neutral
                selectedSprites = sSprite;
            }
        }
        else //neutral
        {
            if (Mathf.Abs(direction.x) > 0) //east or west
            {
                selectedSprites = eSprite;
            }
        }

        return selectedSprites;
    }
}

Sprite Renderer（精灵渲染器） #

该精灵渲染器脚本来自过往相关问题，可在静止物体上实现相机角度更新时的精灵切换效果，但我不清楚如何修改该脚本，使其可适配会移动、朝向动态变化的玩家对象。现有代码如下：

private SpriteRenderer spriteRenderer;

public Transform plane;
public Camera cam;

private const float step = 22.5f;

public Sprite N, NW, W, SW, S, SE, E, NE;
public void Start() => spriteRenderer = GetComponent<SpriteRenderer>();
public void Update()
{
    var projected = Vector3.ProjectOnPlane(cam.transform.forward, plane.up);
    var angle = Vector3.SignedAngle(projected, plane.forward, plane.up);
    
    var AbsAngle = Mathf.Abs(angle);
    
    if (AbsAngle < step) spriteRenderer.sprite = N;
    else if (AbsAngle < step*3) spriteRenderer.sprite = Mathf.Sign(angle) < 0 ? NW : NE;
    else if (AbsAngle < step*5) spriteRenderer.sprite = Mathf.Sign(angle) < 0 ? W : E;
    else if (AbsAngle < step*7) spriteRenderer.sprite = Mathf.Sign(angle) < 0 ? SW : SE;
    else spriteRenderer.sprite = S;
    
    Billboard(spriteRenderer.transform, cam);
}
public void Billboard(Transform character, Camera mainCamera)
{
    var dir = plane.position - mainCamera.transform.position;
    var LookAtRotation = Quaternion.LookRotation(dir);
    
    var LookAtRotationOnly_Y = Quaternion.Euler(character.rotation.eulerAngles.x, LookAtRotation.eulerAngles.y,character.eulerAngles.z);
    character.rotation = LookAtRotationOnly_Y;
}

内容的提问来源于stack exchange，提问作者naturalcrybaby