在遊戲開發中，角色視野跟隨滑鼠位置即第一人稱相機（FPS）是一個很常見的需求，我們今天來實現該功能。

掛載到相機上即可，程式碼如下：

using UnityEngine;
using System.Collections;
//旋轉軸
public enum RotationAxes { 
	MouseXAndY = 0, MouseX = 1, MouseY = 2 
}

public class MouseLook : MonoBehaviour {
	//x軸（水平）速度
	public float sensitivityX = 15F;
	//y軸（垂直）速度
	public float sensitivityY = 15F;
	//x軸（水平）最小旋轉值
	public float minimumX = -360F;
	//x軸（水平）最大旋轉值
	public float maximumX = 360F;
	//y軸（垂直）最小旋轉值
	public float minimumY = -60F;
	//y軸（垂直）最大旋轉值
	public float maximumY = 60F;
    //旋轉軸
	public RotationAxes axes = RotationAxes.MouseXAndY;
	private float rotationY = 0F;

	void Update ()
	{
		if (axes == RotationAxes.MouseXAndY)
		{
			float rotationX = transform.localEulerAngles.y + Input.GetAxis("Mouse X") * sensitivityX;
			
			rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
			rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);
			
			transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);
		}
		else if (axes == RotationAxes.MouseX)
		{
			transform.Rotate(0, Input.GetAxis("Mouse X") * sensitivityX, 0);
		}
		else if (axes == RotationAxes.MouseY)
		{
			rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
			rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);
			
			transform.localEulerAngles = new Vector3(-rotationY, transform.localEulerAngles.y, 0);
		}
	}
	
	void Start ()
	{
		// 確保剛體不改變選轉
		if (GetComponent<Rigidbody>())
			GetComponent<Rigidbody>().freezeRotation = true;
	}
}