Unity3d控制移动方向做圆周运动

MoveAroundCycle.cs

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

public class Move
    : MonoBehaviour
{

    [SerializeField] private Vector3 Anchor;
    [SerializeField] private float Radius;
    [SerializeField] private float Velocity;

    // Use this for initialization

    private float SquaredRadius;
	void Start ()
    {
        this.SquaredRadius = this.Radius * this.Radius;

        var v = new Vector3(-1, -1, 0);

        Debug.Log(string.Format("{0} {1} {2} {3} {4} {5}",
            Mathf.Atan2(1, 1) * 180/Mathf.PI,
            Mathf.Atan2(-1, 1) * 180/Mathf.PI,
            Mathf.Atan2(-1, -1) * 180/Mathf.PI,
            Mathf.Atan2(1, -1) * 180/Mathf.PI, v.Rotate(89), v.Rotate(-89)));
	}
	
	// Update is called once per frame
	void Update ()
    {
        var dir = GetInputDirection();
        if (dir == Vector3.zero)
            return;

        var p = transform.position;
        var v = Anchor - p;
        var dot = Vector2.Dot(dir, v);
        var angleV = Mathf.Atan2(v.y, v.x);

        if (dir != Vector3.zero && dot <= 0 && (p - Anchor).sqrMagnitude >= this.SquaredRadius)
        {
            var angle = v.ToVector2().Cross(dir) >= 0 ? 89 : -89;
            var c = v.ToVector2().Cross(dir);
            if (c > 0.1f)
            {
                angle = 89;
                dir = v.Rotate(angle);
            }
            else if (c < -0.1f)
            {
                angle = -89;
                dir = v.Rotate(angle);
            }
            else
            {
                v = Vector3.zero;
                angle = 0;
                dir = Vector3.zero;
            }
        }

        Debug.Log(string.Format("move dir: {0}", dir));
        var targetPos = p + dir * this.Velocity * Time.deltaTime;
        Debug.DrawLine(p, targetPos, Color.blue, 3.0f);
        transform.position = targetPos;
	}

    private Vector2 GetNewDirection(Vector2 pos, Vector3 dir)
    {
        return dir.Rotate(89);
    }

    private Vector3 Direction = Vector3.zero;
    private Vector3 GetInputDirection()
    {
        this.Direction.x = Input.GetAxis("Horizontal");
        this.Direction.y = Input.GetAxis("Vertical");

        return Direction.normalized;
    }
}

public static class Utils
{
    public static Vector3 Rotate(this Vector3 v, float angle)
    {
        float originRadian = (float)Mathf.Atan2(v.y, v.x);
        float rotateRadian = (float)(angle * Mathf.PI / 180f);
        float dstRadian = originRadian + rotateRadian;

        return new Vector2((float)Mathf.Cos(dstRadian), (float)Mathf.Sin(dstRadian)) * v.magnitude;
    }

    public static float Cross(this Vector2 a, Vector2 b)
    {
        return a.x * b.y - a.y * b.x;
    }

    public static Vector2 ToVector2(this Vector3 v)
    {
        return v;
    }
}