Unity中未请求Google网址

Question

有人可以告诉我为什么这段代码没有请求google网址，只能在queryString中从CENTER开始请求。

如果我需要提供更多信息，请告诉我

非常感谢

public class GoogleMapTile : MonoBehaviour
{
    public enum MapType
    {
        RoadMap,
        Satellite,
        Terrain,
        Hybrid
    }

    //Google Maps API Staticmap URL
    private const string GOOGLE_MAPS_URL = "http://maps.googleapis.com/maps/api/staticmap";

    [Header("Map Settings")]
    [Range(1,20)]
    [Tooltip("Zoom Level, 1=global - 20=house")]
    public int zoomLevel = 1;
    [Tooltip("Type of map, Road, Satellite, Terrain or Hybrid")]
    public MapType mapType = MapType.RoadMap;
    [Range(64,1024)]
    [Tooltip("Size in pixels of the map image")]
    public int size = 640;
    [Tooltip("Double the pixel resolution of the image returned")]
    public bool doubleResolution = true;
    [Tooltip("Defines the origin of the map")]
    public MapLocation worldCenterLocation;

    [Header("Tile Settings")]
    [Tooltip("Sets the tiles position in tile units")]        
    public Vector2 TileOffset;
    [Tooltip("Calculated tile center")]
    public MapLocation tileCenterLocation;
    [Tooltip("Calculated tile corners")]
    public Vector2 TopLeftCorner;
    public Vector2 BottomRightCorner;

    [Header("GPS Settings")]
    [Tooltip("GPS service used to locate world center")]
    public GPSLocationService gpsLocationService;
    private double lastGPSUpdate;

    // Use this for initialization
    void Start ()
    {
        RefreshMapTile ();
    }

    // Update is called once per frame
    void Update ()
    {
        //check if a new location has been acquired
        if (gpsLocationService != null &&
            gpsLocationService.IsServiceStarted && 
            lastGPSUpdate < gpsLocationService.Timestamp)
        {
            lastGPSUpdate = gpsLocationService.Timestamp;
            worldCenterLocation.Latitude = gpsLocationService.Latitude;
            worldCenterLocation.Longitude = gpsLocationService.Longitude;
            print("GoogleMapTile refreshing map texture");
            RefreshMapTile();
        }
    }

    public void RefreshMapTile() {

        StartCoroutine(_RefreshMapTile());
    }

    IEnumerator _RefreshMapTile ()
    {            
        //find the center lat/long of the tile
        tileCenterLocation.Latitude = GoogleMapUtils.adjustLatByPixels(worldCenterLocation.Latitude, (int)(size * 1 * TileOffset.y), zoomLevel);
        tileCenterLocation.Longitude = GoogleMapUtils.adjustLonByPixels(worldCenterLocation.Longitude, (int)(size * 1 * TileOffset.x), zoomLevel);

        var queryString = "";

        //build the query string parameters for the map tile request
        queryString += "center=" + WWW.UnEscapeURL (string.Format ("{0},{1}", tileCenterLocation.Latitude, tileCenterLocation.Longitude));
        queryString += "&zoom=" + zoomLevel.ToString ();
        queryString += "&size=" + WWW.UnEscapeURL (string.Format ("{0}x{0}", size));
        queryString += "&scale=" + (doubleResolution ? "2" : "1");
        queryString += "&maptype=" + mapType.ToString ().ToLower ();
        queryString += "&format=" + "png";

        //adding the map styles
        queryString += "&style=element:geometry|invert_lightness:true|weight:3.1|hue:0x00ffd5";
        queryString += "&style=element:labels|visibility:off";

        //check if script is on a mobile device and using a location service 
        var usingSensor = false;
        #if MOBILE_INPUT
        usingSensor = Input.location.isEnabledByUser 
            && Input.location.status == LocationServiceStatus.Running 
            && gpsLocationService !=null;
        #endif
        queryString += "&sensor=" + (usingSensor ? "true" : "false");

        //set map bounds rect
        TopLeftCorner.x = GoogleMapUtils.adjustLonByPixels(tileCenterLocation.Longitude, -size, zoomLevel);
        TopLeftCorner.y = GoogleMapUtils.adjustLatByPixels(tileCenterLocation.Latitude, size, zoomLevel);

        BottomRightCorner.x = GoogleMapUtils.adjustLonByPixels(tileCenterLocation.Longitude, size, zoomLevel);
        BottomRightCorner.y = GoogleMapUtils.adjustLatByPixels(tileCenterLocation.Latitude, -size, zoomLevel);

        print(string.Format("Tile {0}x{1} requested with {2}", TileOffset.x, TileOffset.y, queryString));

        //finally, we request the image
        var req = new WWW(GOOGLE_MAPS_URL + "?" + queryString);
        //yield until the service responds
        yield return req;
        //first destroy the old texture first
        Destroy(GetComponent<Renderer>().material.mainTexture);
        //when the image returns set it as the tile texture
        GetComponent<Renderer>().material.mainTexture = req.texture;
        print(string.Format("Tile {0}x{1} textured", TileOffset.x, TileOffset.y));
    }
}