unity3d 第一人称脚本解释：MouseLook

using UnityEngine;
using System.Collections;

/// MouseLook rotates the transform based on the mouse delta.
/// Minimum and Maximum values can be used to constrain the possible rotation

/// To make an FPS style character:
/// - Create a capsule.
/// - Add the MouseLook script to the capsule.
///   -> Set the mouse look to use LookX. (You want to only turn character but not tilt it)
/// - Add FPSInputController script to the capsule
///   -> A CharacterMotor and a CharacterController component will be automatically added.

/// - Create a camera. Make the camera a child of the capsule. Reset it's transform.
/// - Add a MouseLook script to the camera.
///   -> Set the mouse look to use LookY. (You want the camera to tilt up and down like a head. The character already turns.)
[AddComponentMenu("Camera-Control/Mouse Look")]
public class MouseLook : MonoBehaviour {
    //3个枚举
    // 这个表示当前控制模式，分别是
    // MouseXAndY上下左右旋转
    // MouseX只能左右旋转
    // MouseY只能上下旋转
    public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }
    public RotationAxes axes = RotationAxes.MouseXAndY;

    // 这俩是左右上下旋转时候的灵敏度
    public float sensitivityX = 15F;
    public float sensitivityY = 15F;

    // 左右旋转的最大角度
    public float minimumX = -360F;
    public float maximumX = 360F;

    //上下旋转最大角度
    public float minimumY = -60F;
    public float maximumY = 60F;

    float rotationY = 0F;

    void Update ()
    {
        //如果是上下左右旋转的模式
        if (axes == RotationAxes.MouseXAndY)
        {
            // 根据鼠标X轴计算摄像机 Y轴旋转角度
            float rotationX = transform.localEulerAngles.y + Input.GetAxis("Mouse X") * sensitivityX;

            // 根据鼠标Y轴计算摄像机x轴旋转角度
            rotationY += Input.GetAxis("Mouse Y") * sensitivityY;

            // 检查上下旋转角度不超过 minimumY和maximumY
            rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

            // 设置摄像机旋转角度
            transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);
        }
        else if (axes == RotationAxes.MouseX)//如果只是左右旋转
        {
            transform.Rotate(0, Input.GetAxis("Mouse X") * sensitivityX, 0);
        }
        else//如果只是上下旋转
        {
            rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
            rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);
            
            transform.localEulerAngles = new Vector3(-rotationY, transform.localEulerAngles.y, 0);
        }
    }
    
    void Start ()
    {
        // 冻结刚体的旋转功能
        // Make the rigid body not change rotation
        if (GetComponent<Rigidbody>())
            GetComponent<Rigidbody>().freezeRotation = true;
    }
}