cbeloch / locate Goto Github PK

Number.extend({
    // Converts the number in degrees to the radian equivalent
    deg2rad: function(angle){
        return (angle / 180) * Math.PI;
    }
});

Location.Measure = {

    OFFSET: 268435456,
    RADIUS: 85445659.4471, // offset / PI

    // Distance between two points on earth can be calculated in several ways.
    // Haversine formula  is reasonably accurate and widely used.
    haversineDistance: function(lat1, lng1, lat2, lng2){
        var latd = Number.deg2rad(lat2 - lat1);
        var lngd = Number.deg2rad(lng2 - lng1);
        var a = Number.sin(latd / 2) * Number.sin(latd / 2) +
        Number.cos(Number.deg2rad(lat1)) * Number.cos(Number.deg2rad(lat2)) *
        Number.sin(lngd / 2) *
        Number.sin(lngd / 2);
        var c = 2 * Number.atan2(Number.sqrt(a), Number.sqrt(1 - a));
        return 6371.0 * c;
    },

    lngToX: function(lng){
        return Number.round(this.OFFSET + this.RADIUS * lng * Math.PI / 180);
    },

    latToY: function(lat){
        return Number.round(this.OFFSET -
        this.RADIUS *
        Number.log((1 + Number.sin(lat * Math.PI / 180)) /
        (1 - Number.sin(lat * Math.PI / 180))) /
        2);
    },

    pixelDistance: function(y1, x1, y2, x2, zoom){
        if (y1 == y2 && x1 == x2) 
            return 0;
        return Number.sqrt(Number.pow((x1 - x2), 2) + Number.pow((y1 - y2), 2)) >> (21 - zoom);
    }
}