Unity3D之触摸输入实现在指定地形上拖拽物体

using UnityEngine;
using System.Collections;

public class TouchTest03 : MonoBehaviour
{
private bool isSelect;
private bool isDrag;

void Awake()
{
isSelect = false;
isDrag = false;
}

void Update()
{
int touchNum = Input.touchCount;

if (touchNum > 0)
{
Touch touch = Input.GetTouch(0);
RaycastHit hit;
Ray ray = Camera.main.ScreenPointToRay(touch.position);
bool isHit = Physics.Raycast(ray, out hit);
switch (touch.phase)
{
case TouchPhase.Began:
if (isHit)
{
if (hit.collider.gameObject == this.gameObject)
{
isSelect = true;
}
}
break;

case TouchPhase.Moved:
isDrag = true;
break;

case TouchPhase.Ended:
case TouchPhase.Canceled:
isDrag = false;
isSelect = false;
break;

default:
break;
}

if (isSelect && isDrag)
{
if (hit.collider.tag == "Terrain")
{
transform.position = new Vector3(hit.point.x, hit.point.y + 0.5f, hit.point.z);
}
}
}
}
}