[转]Unity3D：Gizmos画圆（原创）

 using UnityEngine;
 using System;

 public class HeGizmosCircle : MonoBehaviour
 {
        public Transform m_Transform;
        public float m_Radius = ; // 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 = ; theta <  * Mathf.PI; theta += m_Theta)
               {
                      float x = m_Radius * Mathf.Cos(theta);
                      float z = m_Radius * Mathf.Sin(theta);
                      Vector3 endPoint = new Vector3(x, , z);
                      if (theta == )
                      {
                             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;
        }
 }