各种Camera

　　根据游戏类型的不一样，会需要各种各样的摄像机，下面将分享三种典型的摄像机类型：（1）地下城摄像机；（2）第三人称跟随摄像机；（3）鼠标控制旋转摄像机。将这些控制脚本拖动到场景的MainCamera上即可：

　　看向固定目标的Camera的基本实现，主要使用transform.LookAt函数来实现：

public class LookAtCamera : MonoBehaviour
{
    public GameObject target = null;

    void LateUpdate()
    {
        if (target == null)
            return;

        transform.LookAt(target.transform);
    }
}

　　（1）地下城摄像机，就像暗黑3那样的，摄像机和角色保持固定距离和角度，摄像机不会绕着角色旋转：

public class DungeonCamera : MonoBehaviour
{
    public GameObject target = null;
    public Vector3 offset = Vector3.zero;
    public float damping = 1;

    void Start()
    {
        if (target == null)
            return;
        offset = transform.position - target.transform.position;
    }

    void LateUpdate()
    {
        if (target == null)
            return;

        Vector3 desiredPosition = target.transform.position + offset;
        // 平滑变换过程，即不要立即变换
        Vector3 position = Vector3.Lerp(transform.position, desiredPosition, Time.deltaTime * damping);
        transform.position = position;

        // Camera始终看向目标
        transform.LookAt(target.transform.position);
    }
}

　　（2）第三人称跟随摄像机，比较典型的3D游戏摄像机，摄像机会绕着角色一起旋转：

public class FollowCamera : MonoBehaviour
{
    public GameObject target = null;
    public Vector3 offset = Vector3.zero;
    public float damping = 1;

    void Start()
    {
        if (target == null)
            return;
        offset = transform.position - target.transform.position;
    }

    void LateUpdate()
    {
        float currentAngle = transform.eulerAngles.y;
        float desireAngle = target.transform.eulerAngles.y;
        // 平滑角度变换
        float angle = Mathf.LerpAngle(currentAngle, desireAngle, Time.deltaTime * damping);
        Quaternion rotation = Quaternion.Euler(0, angle, 0);

        transform.position = target.transform.position + (rotation * offset);

        transform.LookAt(target.transform);
    }
}

　　（3）鼠标控制角色旋转摄像机，注意，鼠标控制旋转时不要做Lerp，因为鼠标控制需要精确，比如玩CS的时候，鼠标控制角色转动还要过程那还能玩吗　

public class MouseAimCamera : MonoBehaviour
{
    public GameObject target = null;
    public Vector3 offset = Vector3.zero;
    public float rotateSpeed = 5;

    void Start()
    {
        offset = target.transform.position - transform.position;
    }

    void LateUpdate()
    {
        // 根据鼠标左键旋转目标物体
        float horizontal = Input.GetAxis("Mouse X") * rotateSpeed;
        target.transform.Rotate(0, horizontal, 0);

        float desiredAngle = target.transform.eulerAngles.y;
        Quaternion rotation = Quaternion.Euler(0, desiredAngle, 0);
        transform.position = target.transform.position - (rotation * offset);

        transform.LookAt(target.transform);

    }
}

　　另外为了辅助测试，使用了下面的角色移动/旋转控制脚本：

using UnityEngine;
using System.Collections;

public class Player : MonoBehaviour
{
    public float movementSpeed = 10;
    public float turningSpeed = 60;

    void Update()
    {
        float horizontal = Input.GetAxis("Horizontal") * turningSpeed * Time.deltaTime;
        transform.Rotate(0, horizontal, 0);

        float vertical = Input.GetAxis("Vertical") * movementSpeed * Time.deltaTime;
        transform.Translate(0, 0, vertical);
    }
}

参考：http://code.tutsplus.com/tutorials/unity3d-third-person-cameras--mobile-11230