unity中生成一个GUI格子（始终居中）

1.Script程序

using UnityEngine;
using System.Collections;
 
public class GUITest : MonoBehaviour
{   [SerializeField]
    float width;
    [SerializeField]
    float height;
    float xMin;
    float yMin;
 
    private void Start()
    {
        width = 100;
        height = 100;
 
    }
 
    void OnGUI()
    {
        xMin = 0.5f * Screen.width - width / 2;
        yMin = 0.5f * Screen.height - height / 2;
 
        print("height: "+ Screen.height);
        print("width: "+ Screen.width);
 
        Rect aa = new Rect(xMin, yMin, width, height);
        // Make a background box
        GUI.Box(aa, "GUI_TEST");
    }
}

2.OnGUI函数每隔一定时间被调用一次

void OnGUI()
{}

3.C#中变量定义时顺序不定，不能再声明时使用别的变量的值