Unity之一天一个技术点（十二）---指南针的实现

GUI.skin = compassGUISkin;

var compassAngle : float = transform.rotation.eulerAngles.y;//得到镜头的y轴旋转角度
var compassDiameter : float = 128;
var compassWidth : float = 16;
var compassWindowRect : Rect = Rect (compassPos.x,compassPos.y, compassDiameter, compassDiameter);
GUI.Label (compassWindowRect, "");
var cosAngle : float = Mathf.Cos(compassAngle*Mathf.PI/180);
var sinAngle : float = Mathf.Sin(compassAngle*Mathf.PI/180);
var xMove : float = (compassDiameter*sinAngle/2.0 + compassWidth*cosAngle/2.0);
var yMove : float = (-compassDiameter*cosAngle/2.0 + compassWidth*sinAngle/2.0);
var compassPos : Vector3 = new Vector3(compassPos.x + compassDiameter/2.0 + xMove,compassPos.y + compassDiameter/2.0  + yMove, 0); //position for matrix
var compassQuat : Quaternion = Quaternion.identity; //rotation for matrix
compassQuat.eulerAngles = Vector3(0, 0, compassAngle + 90); //set the rotation to something - rotate around z!
GUI.matrix = Matrix4x4.TRS(compassPos, compassQuat, Vector3.one); //Apply the matrix
GUI.Box(Rect(0, 0, compassDiameter, compassWidth), ""); //notice how the rect starts at 0/0 and the matrix handles the position