unity gizmo绘制圆形帮助调试

using UnityEngine;
using System.Collections;
using System;
public class LearnGrazio : MonoBehaviour {
    public Transform m_Transform;
    public float m_Radius = 1; // 圆环的半径
    public float m_Theta = 0.1f; // 值越低圆环越平滑
    public Color m_Color = Color.green; // 线框颜色
    void Start()
    {
        if (m_Transform == null)
        {
            throw new Exception("Transform is NULL.");
        }
    }
    void OnDrawGizmos()
    {
        if (m_Transform == null) return;
        if (m_Theta < 0.0001f) m_Theta = 0.0001f;
        // 设置矩阵
        Matrix4x4 defaultMatrix = Gizmos.matrix;
        Gizmos.matrix = m_Transform.localToWorldMatrix;
        // 设置颜色
        Color defaultColor = Gizmos.color;
        Gizmos.color = m_Color;
        // 绘制圆环
        Vector3 beginPoint = Vector3.zero;
        Vector3 firstPoint = Vector3.zero;
        for (float theta = 0; theta < 2 * Mathf.PI; theta += m_Theta)
        {
            float x = m_Radius * Mathf.Cos(theta);
            float y = m_Radius * Mathf.Sin(theta);
            Vector3 endPoint = new Vector3(x, y, 0);
            if (theta == 0)
            {
                firstPoint = endPoint;
            }
            else
            {
                Gizmos.DrawLine(beginPoint, endPoint);
            }
            beginPoint = endPoint;
        }
        // 绘制最后一条线段
        Gizmos.DrawLine(firstPoint, beginPoint);
        // 恢复默认颜色
        Gizmos.color = defaultColor; 
        // 恢复默认矩阵
        Gizmos.matrix = defaultMatrix;
    }
}