效果图：

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
 
public class CDrawLine : MonoBehaviour {
    //点数
    public int pointCount = 10;
    //距离---范围半径
    public float radius = 10f;
 
    private float angle;
    private List<Vector3> pointList = new List<Vector3>();
 
    private LineRenderer render;
 
    public bool showRenderer = false;
 
    // Use this for initialization
    void Start () {
        angle = 360f / pointCount;
 
        render = this.GetComponent<LineRenderer>();
 
        //Vector3 vect3 = transform.position + transform.forward * radius;
        //Debug.Log(vect3);
    
    }
    
    // Update is called once per frame
    void Update () {
        if (showRenderer)
        {
            //设置圆的点数
            render.SetVertexCount(pointCount + 1);
 
            Vector3 vect3 = transform.position + transform.forward * radius;
            pointList.Add(vect3);
 
            Quaternion rotation = transform.rotation;
 
            for (int i = 1; i < pointCount; i++)
            {
                //求出第i个 点的旋转 角度
                Quaternion quat = Quaternion.Euler(rotation.eulerAngles.x, rotation.eulerAngles.y - (angle * i), rotation.eulerAngles.z);
 
                vect3 = transform.position + (quat * Vector3.forward) * radius;
 
                pointList.Add(vect3);
            }
 
            for (int j = 0; j < pointList.Count; j++)
            {
                //绘制线条
                //Debug.DrawLine(transform.position, pointList[j], Color.green);
 
                render.SetPosition(j, pointList[j]);
            }
            if (pointList.Count > 0)
                render.SetPosition(pointCount, pointList[0]);
        }
        else
        {
            render.SetVertexCount(0);
        }
 
        //清空list数组
        pointList.Clear();
 
    }
}