Question

I’ve gone through the forums trying to search for solutions, and I’ve adapted my code for several problems I’ve come across, but this one eludes me. I’m trying to plot multiple points on a map (which works) and then draw lines between the points. Each marker contains information, such as latitude and longitude, as well as it’s neighbor (the point that I want to draw the line to). I also give it the color I want the line, as different ‘routes’ can be in different colors. The only I can see being a problem is that I draw a line, set it on the map, and run the loop again for the next marker.

My code places the markers, places the information window for each marker, but doesn’t draw the lines between the markers. Can anyone see where I’ve screwed up, or even if this is possible to do it in the way I’m doing it?

The reason I’m keeping the drawMap function separate is in the event users want to filter out visible data, I need to re-draw the map dynamically. So, I’m keeping the marker list globally so I can reference it even after the function has finished.

My code:

http://www.nku.edu/~sweikatam1/nkuPhysicalMapTest.html

The spot in particular with the issue is the function drawMap, which gets passed an array of objects, markerList, containing the latitude, longitude, color (for the polyline), and other bits of data.
The line placement:

        for(var j = 0; j < markerList.length; j++){
            if(markerList[j].name == markerList[i].neighbor){
                var targetDestination = new google.maps.LatLng(markerList[j].latitude,markerList[j].longitude);
                //alert(markerList[i].latitude + " " + markerList[i].longitude + " \r" + markerList[j].latitude + " " + markerList[j].longitude);
            }
        }
        //set the pathway for the two points
        var flightPlanCoordinates = [
            new google.maps.LatLng(markerList[i].latitude, markerList[i].longitude),
            new google.maps.LatLng(targetDestination)
            ];

            //alert("Color: " + markerList[i].routeColor);
        //set the line and color    
        var flightPath = new google.maps.Polyline({
            path:flightPlanCoordinates,
            strokeColor:markerList[i].routeColor,
            strokeOpacity:2,
            strokeWeight:5
            });
        //apply lines
        flightPath.setMap(map);

The function as a whole:

    function drawMap(markerList){
    //alert("Starting drawMap");


    //create the map
    var map = new google.maps.Map(document.getElementById('map'), {
      zoom: 15,
      center: new google.maps.LatLng(39.032253, -84.465015),
      mapTypeId: google.maps.MapTypeId.HYBRID
    });


    var marker; 
    for (var i = 0; i <markerList.length; i++){
        /*alert("markerList @ i: " + markerList[i].name);
        alert("Marker Data: " + "Name: " + markerList[i].name + "\r "
                            + "Latitude: " + markerList[i].latitude + "\r "
                            + "Longitude: " + markerList[i].longitude + "\r "
                            + "Content Type: " + markerList[i].contentType + "\r "
                            + "Image: " + markerList[i].image
                            + "Color: " + markerList[i].routeColor);*/
        var contentData = '<b>'+markerList[i].name +'</b>: '
                            + markerList[i].latitude + ' x ' 
                            + markerList[i].longitude + '<br/><p>'
                            + markerList[i].contentType 
                            +'</p><img src="' + markerList[i].image + " height=150 width=100>";

        //create the marker

        marker = new google.maps.Marker({
            position: new google.maps.LatLng(markerList[i].latitude,markerList[i].longitude),
            draggable: false,
            icon: markerList[i].icon,
            map:map,
            content: contentData,
            title:markerList[i].name
        });

        //find the neighbor for the current marker and set the destination coordinates
        for(var j = 0; j < markerList.length; j++){
            if(markerList[j].name == markerList[i].neighbor){
                var targetDestination = new google.maps.LatLng(markerList[j].latitude,markerList[j].longitude);
                //alert(markerList[i].latitude + " " + markerList[i].longitude + " \r" + markerList[j].latitude + " " + markerList[j].longitude);
            }
        }
        //set the pathway for the two points
        var flightPlanCoordinates = [
            new google.maps.LatLng(markerList[i].latitude, markerList[i].longitude),
            new google.maps.LatLng(targetDestination)
            ];

            //alert("Color: " + markerList[i].routeColor);
        //set the line and color    
        var flightPath = new google.maps.Polyline({
            path:flightPlanCoordinates,
            strokeColor:markerList[i].routeColor,
            strokeOpacity:2,
            strokeWeight:5
            });
        //apply lines
        flightPath.setMap(map);

        //handle open information windows
        google.maps.event.addListener(marker,'click', function(){
            closeInfos();
            var info = new google.maps.InfoWindow({content: this.content});
            info.open(map,this);
            infos[0]=info;
            });
            //alert("Marker " + markerList[i].name + " placed.");


    }
    //alert("drawMap complete. Drawing lines");

    <!-- DRAWING LINES COMPLETE -->
}

If anything here seems odd, confusing, or needs clarification, please let me know. Criticisms and ways of doing things better are always welcome. Thanks guys!

Answer 1

In defining, flightPlanCoordinates, the second LatLng was being created out of another LatLng (targetDestination). So just remove the new google.maps.LatLng portion and use the targetDestination directly. With this change, I saw a blue zigzag and a red one being drawn on the map.

var flightPlanCoordinates = [
    new google.maps.LatLng(markerList[i].latitude, markerList[i].longitude),
    targetDestination
];