openlayer读取三种类型的本地瓦片的计算公式

1.arcgis server瓦片的计算公式及geturl方法：

getURL: function(bounds){
     var lon1=bounds.left;
     var lat1=bounds.top;
     var lon2=bounds.right;
     var lat2=bounds.bottom;
        var picHeight=256;    //图片大小 
        var picResolution,picRow,picCol;   //分辨率,所求图片行号,列号
        var tileOriginX,tileOriginY;    //切图原点
        var iResolution = this.map.getResolution();
        var temp1=new Array();
        var i,zoom=0,path;    //zoom代表缩放级别；
       
  tileOriginX=this.tileOrigin.lon;

  tileOriginY=this.tileOrigin.lat;

  //计算zoom
  zoom=this.map.getZoom();

  //获得行列号(使用瓦片的中心点经纬度计算)
   picRow=Math.ceil(Math.abs((tileOriginY-(lat1+lat2)/2)/(iResolution*picHeight)))-1;

   picCol=Math.ceil(Math.abs((tileOriginX-(lon1+lon2)/2)/(iResolution*picHeight)))-1; 

  //计算瓦片路径,把级别、行列十进制转化为十六进制
  zoom=zoom.toString(16);
  picRow=picRow.toString(16);
  picCol=picCol.toString(16);
  var zoomTemp="00"+zoom.toString();
  var picRowTemp="00000000"+picRow.toString();
  var picColTemp="00000000"+picCol.toString();
  zoom="L"+zoomTemp.substring(zoom.length,zoom.length+2);
  picRow="R"+picRowTemp.substring(picRow.length,picRow.length+8);
  picCol="C"+picColTemp.substring(picCol.length,picCol.length+8);
  path=this.url+"+zoom+"/"+picRow+"/"+picCol+".jpg";
  //alert(path);
  return path;
      },  //end function

2.google瓦片的geturl方法：

getURL: function(bounds){
  var x = Math.round(Math.pow(2,this.map.getZoom())*(bounds.left+180)/360);   
        x = Math.round(x);   
        var y = Math.round(Math.pow(2,this.map.getZoom()-1)*(90-bounds.top)/180+Math.pow(2,this.map.getZoom()-2));   
        var z = this.map.getZoom(); 
        return "../../googleMap/m_"+z+"_"+x+"_"+y+".png";  
  
    },

3.天地图瓦片的geturl方法：

getURL: function(bounds){
     var lon1=bounds.left;
     var lat1=bounds.top;
     var lon2=bounds.right;
     var lat2=bounds.bottom;
        var picHeight=256;    //图片大小 
        var picResolution,picRow,picCol;   //分辨率,所求图片行号,列号
        var tileOriginX,tileOriginY;    //切图原点
        var iResolution = this.map.getResolution();
        var temp1=new Array();
        var i,zoom=0,path;    //zoom代表缩放级别；
       
         tileOriginX=-180;
         tileOriginY=90;
       //计算zoom
       zoom=this.map.getZoom();

       //计算行列号(使用瓦片的中心点经纬度计算)
       picRow=Math.ceil(Math.abs((tileOriginY-(lat1+lat2)/2)/(iResolution*picHeight)))-1;
       picCol=Math.ceil(Math.abs((tileOriginX-(lon1+lon2)/2)/(iResolution*picHeight)))-1; 
       path="../../china/"+zoom+"/"+picRow+"/"+picCol+".png"
       //alert(path);
       return path;
      },  //end function