请写一个方法，传入一个中心点，传入一个半径，用LineRenderer画一个圆出来

public class TestLineRenderer : MonoBehaviour
{
    public Material m;
    void Start()
    {
        DrawCirCle(Vector3.zero, 5);
    }

/// <summary>
/// 根据圆心和半径画圆
/// </summary>
/// <param name="center">圆心</param>
/// <param name="rad">半径</param>
    void DrawCirCle(Vector3 center, float rad)
    {
        //添加LineRenderer组件
        LineRenderer line = gameObject.AddComponent<LineRenderer>();
        //设置线的材质
        line.material = m;
        //设置起始点相连
        line.loop = true;
        //设置线宽
        line.startWidth = 0.02f;
        line.endWidth = 0.02f;
        //设置线有多少个点
        line.positionCount = 180;

        //计算每个点相距的角度
        float angleOnce = 360 / line.positionCount;
        //设置线上点的数组
        Vector3[] circlePoints = new Vector3[line.positionCount];
        //起始向量
        Vector3 vecStart = new Vector3(0, rad, 0);
        for (int i = 0; i < line.positionCount; i++)
        {           
            //四元数乘向量代表向量的旋转，值为Vector3类型
            //向量加点代表移动该点
            circlePoints[i] = Quaternion.Euler(0, 0, angleOnce * i) * vecStart + center;
        }
        //画线
        line.SetPositions(circlePoints);
    }
}