// Create polygon method for collision detection
GPolygon.prototype.containsLatLng = function(latLng) {
    // Do simple calculation so we don't do more CPU-intensive calcs for obvious misses
    var bounds = this.getBounds();
   
    if(!bounds.containsLatLng(latLng)) {
        return false;
    }
   
    var numPoints = this.getVertexCount();
    var inPoly = false;
    var i;
    var j = numPoints-1;
   
    for(var i=0; i < numPoints; i++) {
        var vertex1 = this.getVertex(i);
        var vertex2 = this.getVertex(j);
       
        if (vertex1.lng() < latLng.lng() && vertex2.lng() >= latLng.lng() || vertex2.lng() < latLng.lng() && vertex1.lng() >= latLng.lng())  {
            if (vertex1.lat() + (latLng.lng() - vertex1.lng()) / (vertex2.lng() - vertex1.lng()) * (vertex2.lat() - vertex1.lat()) < latLng.lat()) {
                inPoly = !inPoly;
            }
        }
       
        j = i;
    }
   
    return inPoly;
};