OpenLayers：如何计算两点之间的距离？

如何使用墨卡托投影计算 OpenLayers 中两点之间的距离？

Thanks

use point1.distanceTo(point2)

var Geographic  = new OpenLayers.Projection("EPSG:4326"); 
var Mercator = new OpenLayers.Projection("EPSG:900913");


function distanceBetweenPoints(latlng1, latlng2){
        var point1 = new OpenLayers.Geometry.Point(latlng1.lon, latlng1.lat).transform(Geographic, Mercator);
        var point2 = new OpenLayers.Geometry.Point(latlng2.lon, latlng2.lat).transform(Geographic, Mercator);       
        return point1.distanceTo(point2);
    }