Unity3d中C#获取微软卫星瓦片地图

public string TileXYToQuadKey(int tileX, int tileY, int levelOfDetail)
{
  StringBuilder quadKey = new StringBuilder();
  for (int i = levelOfDetail; i > 0; i--)
  {
      char digit = '0';
      int mask = 1 << (i - 1);
      if ((tileX & mask) != 0)
      {
          digit++;
      }
      if ((tileY & mask) != 0)
      {
          digit++;
          digit++;
      }
      quadKey.Append(digit);
  }
  return quadKey.ToString();
}

string quadkeys = TileXYToQuadKey(xTile, yTile, zoomLevel);
string url = string.Format("http://{0}{1}.ortho.tiles.virtualearth.net/tiles/{0}{2}.{3}?g={4}", "a", 1, quadkeys, "png", 50);

//url为下载地址