滑动效果图：

 做法：

把下面的Camera.cs脚本放在相机上，并给代码中的FollowObject拖拽被观察物体（旋转中心）即可

using UnityEngine;
public class Camera : MonoBehaviour {public Transform FollowObject;  //被跟随的物体private Vector2 MouseStart, MouseEnd;private Vector3 DeltAngle;private float CameraDistence = 100;   //相机与其跟随物体保持的距离private float delt, deltz;private float PI = 3.14159f;private Vector3 DeltPosition;private bool IsDrag = false;void Start() {DeltAngle = gameObject.transform.localEulerAngles;}void LateUpdate() {if (IsDrag) {MouseStart = MouseEnd;MouseEnd = Input.mousePosition;DeltAngle.x -= (MouseEnd.y - MouseStart.y) / 7;DeltAngle.y += (MouseEnd.x - MouseStart.x) / 7;gameObject.transform.localEulerAngles = DeltAngle;delt = gameObject.transform.localEulerAngles.y * PI / 180;deltz = gameObject.transform.localEulerAngles.x * PI / 180;gameObject.transform.position = FollowObject.position + new Vector3(-CameraDistence * Mathf.Sin(delt) * Mathf.Cos(deltz), CameraDistence * Mathf.Sin(deltz), -CameraDistence * Mathf.Cos(delt) * Mathf.Cos(deltz));}}void OnGUI() {if (Event.current.type == EventType.MouseDown) MouseEnd = Input.mousePosition;if (Event.current.type == EventType.MouseDrag) IsDrag = true;if (Event.current.type == EventType.MouseUp) IsDrag = false;}
}