Unity Mesh 创建圆 利用VertexHelper 设置UV坐标贴图

//把圆分成多少分三角
    public int n = 5;
    //半径
    public int r = 5;
    // Start is called before the first frame update
    void Start()
    {
        VertexHelper vh=new VertexHelper();

         Mesh mesh = new Mesh();

        //顶点坐标  顶点颜色  uv坐标
        //添加顶点
        vh.AddVert(Vector3.zero, Color.white,new Vector2(0.5f,0.5f));

      
        float ang = 2 * Mathf.PI / n;//求每个的角度

        for (int i = 0; i < n; i++)
        {
            //对边  求x
            float x = Mathf.Sin(i * ang) * r;
            //临边  求 y
            float y=Mathf.Cos(i * ang) * r;
            //添加顶点
            float uvx = (x + r) / (2 * r);
            float uvy = (y + r) / (2 * r);

            vh.AddVert(new Vector3(x,0,y), Color.white, new Vector2(uvx, uvy));
           
            if (i == n - 1)
            {
              //渲染
                vh.AddTriangle(0, i + 1, 1);
            }
            else
            {
                vh.AddTriangle(0, i + 1, i+2);
            }
        }
        vh.FillMesh(mesh);//附加给mesh
        GetComponent().mesh = mesh; 
        GetComponent().sharedMesh = mesh;