问题:

On my page, when it loads it gets your location and sets a marker on your spot, then I want it to load all markers from my database and set them on the map, but I only want to load markers that are within 1km of their location. I'm trying to set it up but I'm having a bit of trouble.

So the markers are loaded from the database like so:

<?php while($stmt -> fetch()) { ?> var longi = "<?php echo $gLongitude; ?>"; var lati = "<?php echo $gLatitude; ?>"; var title = "<?php echo $gTitle; ?>"; setMarker(lati, longi, title); <?php } $stmt -> close(); $mysqli -> close();?>

and then the setMarker function calls like this:

function setMarker(lati, longi, title) {     var latLongMarker = new google.maps.LatLng(lati,longi);     marker = new google.maps.Marker({         position: latLongMarker,         map: map,         draggable: false,         title: title     });     arrMarkers.push(marker); }

That all works fine and dandy, and loads all the markers from the database onto the map but how might I load only ones that are 1km from me? I read about computeDistanceBetween() but I can't find an example to save my life. Thanks everybody in advance.

I ended up working out a way to do it that ended up being much easier and faster to process here you go for anybody looking for this in the future:

        <?php while($stmt -> fetch()) { ?>         var longi = "<?php echo $gLongitude; ?>";         var lati = "<?php echo $gLatitude; ?>";         var title = "<?php echo $gTitle; ?>";         var content = 'Bus arrives at: ' + "<?php echo $gWeekdayDay; ?>";         database.push({latitude: lati, longitude: longi, markerTitle: title, content: content});         <?php } $stmt -> close(); $mysqli -> close();?>  for (var i = 0; i < database.length; i++) {                     createMarker(database[i].latitude, database[i].longitude, database[i].markerTitle, initialLocation,                          database[i].content);                 }  function createMarker(lati, longi, title, myPosition, content) {     var latLongMarker = new google.maps.LatLng(lati, longi);     distanceCompare.push({position: latLongMarker, markerTitle: title});     setMarker(myPosition, latLongMarker, title, content); }  function setMarker(myPosition, latLongMarker, title, content) {          distance = google.maps.geometry.spherical.computeDistanceBetween(latLongMarker, myPosition);         console.log('Distance of '+latLongMarker+ 'and original position' + myPosition + 'Is equal to '+distance);             updateResults();         if (distance < setDistance) {             addMarker(latLongMarker, title, content);             stopsfound++;             updateResults();             console.log(content);         } }  function addMarker(position, title, content) {     console.log('Adding Marker ' + content);     marker = new google.maps.Marker({         position: position,         map: map,         title: title     });     bindInfoWindow(marker, content);     markersArray.push(marker); }

回答1:

You will need to use the Haversine formaula. The code below uses this formula using PDO. You will need change it for $mysqli.

$stmt = $dbh->prepare("SELECT  name, lat, lng, (6372.8 * acos( cos( radians(?) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(?) ) + sin( radians(?) ) * sin( radians( lat ) ) ) ) AS distance FROM mytable HAVING distance < 1 ORDER BY distance ASC LIMIT 0 , 20");     // Assign parameters     $stmt->bindParam(1,$center_lat);//Coordinates of location     $stmt->bindParam(2,$center_lng);//Coordinates of location     $stmt->bindParam(3,$center_lat);

This query was used in this DEMO

回答2:

first, you need create a table, call places, for example, and this need have the fields lat and long. Then you need create a query that get the places of a radius (km or milles) here an example of the query

public function getRecents($nro_places, $lat='-33.45287', $lng='-70.58598') {     $query = Doctrine_Query::create();     $query->select('p.*, ( 6371 * acos( cos( radians('.$lat.') ) * cos( radians( m.lat ) ) * cos( radians( m.lng ) - radians('.$lng.') ) + sin( radians('.$lat.') ) * sin( radians( m.lat ) ) ) ) AS distance'); //this is all you need     $query->from('Places p, p.Maps m');     $query->having('distance < 3'); //3kms     $query->where('status = 1'); //places enabled     $query->orderBy('p.created_at DESC, distance ASC');     $query->limit($nro_places);     $result = $query->execute(array(), Doctrine_Core::HYDRATE_ARRAY);      return $result; }

Here an example of the query with the query that you need. http://wiki.linuxservertech.com/faq/index.php?action=artikel&cat=4&id=7&artlang=en

hope this help

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