内容一：了解transform中Rotate和移动针对3D物体和2D物体的实现

3D：使用Rotate可是直接使用目标点【Rotate(vector3)】
2D：使用Rotate需要控制Recttransform中Rotate的角度【使用两个向量得计算夹角(vector.Angle),规定好UI的锚点(确定旋转分割线),】，每次修改角度都需要重置初始(否者会发生旋转)

内容二：了解向量Vector的操作函数

向量长度：Vector.magnitude
向量夹角：Vector.Angle
点乘叉乘：Vector.Dot【夹角和方向】 Vector.Cross

内容三：常用Mathf的操作函数

Mathf.Sin
Mathf.Cos

脚本实现：绘制圆环点

    public Transform ConterPoint;
    public int r = 5;
    public int R = 5;
    [Header("值越小越精确")]
    public int multiple = 5;
    private Vector3 VP1;
    private Vector3 VP2;
    private Vector3 VConter;
    private List<GameObject> InstantiatePoint = new List<GameObject>();
    private List<Transform> DrawPointDown = new List<Transform>();
    private List<Transform> DrawPointUp = new List<Transform>();
    
public void OnDrawPath(Transform P1, Transform P2)
{
        VP1 = P1.position;
        VP2 = P2.position;
        VConter = ConterPoint.position;
        
//记录P1/P2角度
        Vector3 ConterP1 = VP1 - VConter;
        Vector3 ConterP2 = VP2 - VConter;
        float AngP1P2 = Vector3.Angle(ConterP1, ConterP2);
        float AngRightConterP1 = Vector3.Angle(Vector3.right, ConterP1);
        float AngRightConterP2 = Vector3.Angle(Vector3.right, ConterP2);
        float Contrast = AngRightConterP1 > AngRightConterP2 ? AngRightConterP2 : AngRightConterP1;


          for (int i = (int)Contrast; i < (AngP1P2 + Contrast); i += multiple, index++)
            {
                float x = VConter.x + r * Mathf.Cos(i * 3.14f / 180);
                float y = VConter.y + r * Mathf.Sin(i * 3.14f / 180);
                if (InstantiatePoint.Count > index)
                {
                    InstantiatePoint[index].transform.position = new Vector3(x, y, VConter.z);
                    InstantiatePoint[index].SetActive(false);
                    DrawPointDown.Add(InstantiatePoint[index].transform);
                }
                else
                {
                    GameObject obj = GameObject.Instantiate(DrowObj, new Vector3(x, y, VConter.z), Quaternion.identity);
                    obj.transform.SetParent(InstantiateParent);
                    obj.name = index.ToString();
                    obj.SetActive(false);
                    InstantiatePoint.Add(obj);
                    DrawPointDown.Add(obj.transform);
                }
            }

for (int i = (int)Contrast; i < (AngP1P2 + Contrast); i += multiple, index++)
            {
                float x = VConter.x + (r + R) * Mathf.Cos(i * 3.14f / 180);
                float y = VConter.y + (r + R) * Mathf.Sin(i * 3.14f / 180);
                if (InstantiatePoint.Count > index)
                {
                    InstantiatePoint[index].transform.position = new Vector3(x, y, VConter.z);
                    InstantiatePoint[index].SetActive(false);
                    DrawPointUp.Add(InstantiatePoint[index].transform);
                }
                else
                {
                    GameObject obj = GameObject.Instantiate(DrowObj, new Vector3(x, y, VConter.z), Quaternion.identity);
                    obj.transform.SetParent(InstantiateParent);
                    obj.name = index.ToString();
                    obj.SetActive(false);
                    InstantiatePoint.Add(obj);
                    DrawPointUp.Add(obj.transform);
                }
            }
            
 Transform[] Meak = new Transform[DrawPointDown.Count + DrawPointUp.Count];
            int j = 0;
            bool ibol = true;
            for (int i = 0; i < Meak.Length; i += 2, j += 1, ibol = !ibol)
            {
                if (ibol)
                {
                    Meak[i + 0] = DrawPointDown[j];
                    Meak[i + 1] = DrawPointUp[j];
                }
                else
                {
                    Meak[i + 0] = DrawPointUp[j];
                    Meak[i + 1] = DrawPointDown[j];
                }
            }
            DrawPathScript.pos = Meak;
}

脚本实现：绘制圆环

 [SerializeField]
    public Transform[] pos;

    // 自己手动刷新
    void Update()
    {
        //SetNativeSize();
        SetVerticesDirty();
    }
    protected override void OnPopulateMesh(VertexHelper vh)
    {
        vh.Clear();//清理重置
        vh.Dispose();//清理内容
        if (pos == null) return;
        if (pos.Length == 0) return;
        Color32 color32 = color;
        vh.Clear();

        int j = 0;
        try
        {
            for (int i = 0; i < pos.Length; i++)
            {
                if (pos[i] == null)
                {
                    Debug.Log("存在空值" + i);
                    continue;
                }
                j = i;
                vh.AddVert(pos[i].localPosition, color32, new Vector2(0f, 1f));
            }
        }
        catch (System.Exception)
        {
            Debug.Log(j);
            throw;
        }
        //四边形
        UIVertex uI1 = new UnityEngine.UIVertex();
        UIVertex uI2 = new UnityEngine.UIVertex();
        UIVertex uI3 = new UnityEngine.UIVertex();
        UIVertex uI4 = new UnityEngine.UIVertex();
        //动态绘制
        for (int i = 0; i < pos.Length; i += 2)
        {
            if (i + 3 >= pos.Length) continue;
            vh.PopulateUIVertex(ref uI1, i);
            vh.PopulateUIVertex(ref uI2, i + 1);
            vh.PopulateUIVertex(ref uI3, i + 2);
            vh.PopulateUIVertex(ref uI4, i + 3);
            var UIVertex1 = new UIVertex[4] { uI1, uI2, uI3, uI4 };
            vh.AddUIVertexQuad(UIVertex1);
        }
    }