Openlayers3 加載百度地圖，天地圖

openlayers3 加載百度地圖：

var projection = ol.proj.get("EPSG:3857");
    var resolutions = [];
    for(var i=0; i<19; i++){
        resolutions[i] = Math.pow(2, 18-i);
    }
    var tilegrid  = new ol.tilegrid.TileGrid({
        origin: [0,0],
        resolutions: resolutions
    });

    var baidu_source = new ol.source.TileImage({
        projection: projection,
        tileGrid: tilegrid,
        tileUrlFunction: function(tileCoord, pixelRatio, proj){
            if(!tileCoord){
                return "";
            }
            var z = tileCoord[0];
            var x = tileCoord[1];
            var y = tileCoord[2];

            if(x<0){
                x = "M"+(-x);
            }
            if(y<0){
                y = "M"+(-y);
            }

            return "http://online3.map.bdimg.com/onlinelabel/?qt=tile&x="+x+"&y="+y+"&z="+z+"&styles=pl&udt=20151021&scaler=1&p=1";
        }
    });

    var baidu_layer = new ol.layer.Tile({
        source: baidu_source
    });

    var map = new ol.Map({
        target: 'map',
        layers: [baidu_layer],
        view: new ol.View({
            center:  [12959773,4853101],
            zoom: 12
        })
    });

openlayers3 加載天地圖：

路網
var tian_di_tu_road_layer = new ol.layer.Tile({
    title: "天地圖路網",
    source: new ol.source.XYZ({
        url: "http://t4.tianditu.com/DataServer?T=vec_w&x={x}&y={y}&l={z}"
    })
});
map.addLayer(tian_di_tu_road_layer);
註記
var tian_di_tu_annotation = new ol.layer.Tile({
    title: "天地圖文字標註",
    source: new ol.source.XYZ({
        url: 'http://t3.tianditu.com/DataServer?T=cva_w&x={x}&y={y}&l={z}'
    })
});
map.addLayer(tian_di_tu_annotation);
衛星影像
var tian_di_tu_satellite_layer = new ol.layer.Tile({
    title: "天地圖衛星影像",
    source: new ol.source.XYZ({
        url: 'http://t3.tianditu.com/DataServer?T=img_w&x={x}&y={y}&l={z}'
    })
});
map.addLayer(tian_di_tu_satellite_layer);