谷歌地图，折线绘制＆＃34;额外＆＃34;直线 - 无法看到

Question

我查询2＆＃34;设置＆＃34;来自数据库的坐标，显示我们已经飞过气球的轨道。 我在起飞和着陆期间放置标记。 现在我想在2个轨道中的起飞和着陆之间绘制折线，但由于某种原因，也有2个着陆点与折线相连。 示例：http://minballontur.dk/all/showtracknew.php

我无法弄清楚会发生什么 - 我尝试在每个循环中将坐标数组的长度写为0，但它没有帮助。

function load() {
   var lastlat;
   var lastlng;
      var map = new google.maps.Map(document.getElementById("map"), {
        center: new google.maps.LatLng(55.44, 11.80),
        zoom: 17,
        mapTypeId: google.maps.MapTypeId.ROADMAP
      });
    var infoWindow = new google.maps.InfoWindow;
    var flightPlanCoordinates = [];

<?php while($row = mysql_fetch_array($result)) { ?>
      // Change this depending on the name of your PHP file
      flightPlanCoordinates.length = 0;
      downloadUrl("phpsqlajax_genxmlall.php?LogDate=<?php echo $row['Log_Date'] ?>&TimeOfDay=<?php echo $row['TimeOfDay'] ?>&Log_Name=<?php echo $row['Log_Name'] ?>", function(data) {
        var xml = data.responseXML;
        var markers = xml.documentElement.getElementsByTagName("marker");
        for (var i = 0; i < markers.length; i++) {
          flightPlanCoordinates[i] = new google.maps.LatLng(markers[i].getAttribute("lat"), markers[i].getAttribute("lng"));
        }

      flightPath = new google.maps.Polyline({
                path: flightPlanCoordinates,
                strokeColor: "#0000FF",
                strokeOpacity: 0.8,
                strokeWeight: 2
                });
      flightPath.setMap(map);

          //Show first marker
      var name = markers[0].getAttribute("name");
      var address = markers[0].getAttribute("address");
      var type = markers[0].getAttribute("BalloonStatus");
      var point = new google.maps.LatLng(
      parseFloat(markers[0].getAttribute("lat")),
      parseFloat(markers[0].getAttribute("lng")));
      var html = "<div style = 'height:75px;width:250px'><b>" + name + "</b> <br/>" + address +"<br/> Status : "+type;
      var icon = customIcons[type] || {};
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        icon: icon.icon,
        shadow: icon.shadow
      });
      bindInfoWindow(marker, map, infoWindow, html);
      lastlat = markers[0].getAttribute("lat");
      lastlng = markers[0].getAttribute("lng");

      //Show last marker
      var point1 = new google.maps.LatLng(
              parseFloat(markers[0].getAttribute("lat")),
              parseFloat(markers[0].getAttribute("lng")));
      var point2 = new google.maps.LatLng(
              parseFloat(markers[markers.length-1].getAttribute("lat")),
              parseFloat(markers[markers.length-1].getAttribute("lng")));

      var distance = getDistance(point1, point2);
      var distancekm = Math.round((distance/1000)*10)/10;
      var name = markers[markers.length-1].getAttribute("name");
      var address = markers[markers.length-1].getAttribute("address");
      var type = markers[markers.length-1].getAttribute("BalloonStatus");
      var point = new google.maps.LatLng(
          parseFloat(markers[markers.length-1].getAttribute("lat")),
          parseFloat(markers[markers.length-1].getAttribute("lng")));
      var html = "<div style = 'height:75px;width:250px'><b>" + name + "</b> <br/>" + address +"<br/>Distance : "+ distancekm +" km<br/> Status : "+type;
      var icon = customIcons[type] || {};
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        icon: icon.icon,
        shadow: icon.shadow
      });
      bindInfoWindow(marker, map, infoWindow, html);
      lastlat = markers[markers.length-1].getAttribute("lat");
      lastlng = markers[markers.length-1].getAttribute("lng");

    var bounds = new google.maps.LatLngBounds();
     for (var i = 0; i < markers.length; i++) {
         bounds.extend(new google.maps.LatLng(markers[i].getAttribute("lat"), markers[i].getAttribute("lng")));
    }

       map.fitBounds(bounds);

      }); //Downlaod URL 
  <?php } ?>  //End DB Loop
} // Load

Answer 1

您在两个异步回调函数中使用相同的坐标数组。在它们中的任何一个运行之前，它被重置为回调函数之外的0长度，所以你最终得到了第二个折线中所有坐标的所有坐标。

这样的事情应该有效：

function load() {
   var lastlat;
   var lastlng;
      var map = new google.maps.Map(document.getElementById("map"), {
        center: new google.maps.LatLng(55.44, 11.80),
        zoom: 17,
        mapTypeId: google.maps.MapTypeId.ROADMAP
      });
    var infoWindow = new google.maps.InfoWindow;

<?php while($row = mysql_fetch_array($result)) { ?>
      downloadUrl("phpsqlajax_genxmlall.php?LogDate=<?php echo $row['Log_Date'] ?>&TimeOfDay=<?php echo $row['TimeOfDay'] ?>&Log_Name=<?php echo $row['Log_Name'] ?>", function(data) {
        // declare a new array of coordinates in each callback function.
        var flightPlanCoordinates = [];
        var xml = data.responseXML;
        var markers = xml.documentElement.getElementsByTagName("marker");
        for (var i = 0; i < markers.length; i++) {
          flightPlanCoordinates[i] = new google.maps.LatLng(markers[i].getAttribute("lat"), markers[i].getAttribute("lng"));
        }

      flightPath = new google.maps.Polyline({
                path: flightPlanCoordinates,
                strokeColor: "#0000FF",
                strokeOpacity: 0.8,
                strokeWeight: 2
                });
      flightPath.setMap(map);

          //Show first marker
      var name = markers[0].getAttribute("name");
      var address = markers[0].getAttribute("address");
      var type = markers[0].getAttribute("BalloonStatus");
      var point = new google.maps.LatLng(
      parseFloat(markers[0].getAttribute("lat")),
      parseFloat(markers[0].getAttribute("lng")));
      var html = "<div style = 'height:75px;width:250px'><b>" + name + "</b> <br/>" + address +"<br/> Status : "+type;
      var icon = customIcons[type] || {};
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        icon: icon.icon,
        shadow: icon.shadow
      });
      bindInfoWindow(marker, map, infoWindow, html);
      lastlat = markers[0].getAttribute("lat");
      lastlng = markers[0].getAttribute("lng");

      //Show last marker
      var point1 = new google.maps.LatLng(
              parseFloat(markers[0].getAttribute("lat")),
              parseFloat(markers[0].getAttribute("lng")));
      var point2 = new google.maps.LatLng(
              parseFloat(markers[markers.length-1].getAttribute("lat")),
              parseFloat(markers[markers.length-1].getAttribute("lng")));

      var distance = getDistance(point1, point2);
      var distancekm = Math.round((distance/1000)*10)/10;
      var name = markers[markers.length-1].getAttribute("name");
      var address = markers[markers.length-1].getAttribute("address");
      var type = markers[markers.length-1].getAttribute("BalloonStatus");
      var point = new google.maps.LatLng(
          parseFloat(markers[markers.length-1].getAttribute("lat")),
          parseFloat(markers[markers.length-1].getAttribute("lng")));
      var html = "<div style = 'height:75px;width:250px'><b>" + name + "</b> <br/>" + address +"<br/>Distance : "+ distancekm +" km<br/> Status : "+type;
      var icon = customIcons[type] || {};
      var marker = new google.maps.Marker({
        map: map,
        position: point,
        icon: icon.icon,
        shadow: icon.shadow
      });
      bindInfoWindow(marker, map, infoWindow, html);
      lastlat = markers[markers.length-1].getAttribute("lat");
      lastlng = markers[markers.length-1].getAttribute("lng");

    var bounds = new google.maps.LatLngBounds();
     for (var i = 0; i < markers.length; i++) {
         bounds.extend(new google.maps.LatLng(markers[i].getAttribute("lat"), markers[i].getAttribute("lng")));
    }

       map.fitBounds(bounds);

      }); //Download URL 
  <?php } ?>  //End DB Loop
} // Load