这种方法最简单可以实现相机跟随角色平移

1：计算相机和目标物体的距离 

 offset = this.transform.position - target.transform.position;

2：Update方法中实时变化相机位置

 this.transform.position = target.transform.position + offset;

3：镜头缩放

  //镜头缩放

    public void CamRotation() {


        if (Input.GetAxis("Mouse ScrollWheel") != 0)
        {
            //鼠标滚动滑轮 值就会变化
            if (Input.GetAxis("Mouse ScrollWheel") < 0)
            {
                //范围值限定
                if (Camera.main.fieldOfView <= 100)//摄像机采用Perspective透视
                    Camera.main.fieldOfView += 2;
                if (Camera.main.orthographicSize <= 20)//摄像机采用Orthograpic正交
                    Camera.main.orthographicSize += 0.5F;
            }
            //Zoom in  
            if (Input.GetAxis("Mouse ScrollWheel") > 0)
            {
                //范围值限定
                if (Camera.main.fieldOfView > 2)//摄像机采用Perspective透视
                    Camera.main.fieldOfView -= 2;
                if (Camera.main.orthographicSize >= 1)//摄像机采用Orthograpic正交
                    Camera.main.orthographicSize -= 0.5F;
            }
        }

    }