让 GUI 围绕一个点旋转的 Helper 函数。
修改 GUI.matrix 可以让所有 GUI 元素围绕 pivotPoint 旋转 angle 度。
另请参阅：GUI.matrix、ScaleAroundPivot。
using UnityEngine;
using System.Collections;
public class ExampleClass : MonoBehaviour {
private float rotAngle = 0;
private Vector2 pivotPoint;
void OnGUI() {
pivotPoint = new Vector2(Screen.width / 2, Screen.height / 2);
GUIUtility.RotateAroundPivot(rotAngle, pivotPoint);
if (GUI.Button(new Rect(Screen.width / 2 - 25, Screen.height / 2 - 25, 50, 50), "Rotate"))
rotAngle += 10;
}
}