Need help calculating longitude and latitude midpoint using javascript from php values
I am currently working on a project and have run into quite a snag. I am running a mapping application using the google maps API and I need to calculate the midpoint between two points, which are 4 total pts (lat/long) which are stored as php values from a user.
The formula I am currently using needs to convert my values which are in degrees, to radians. And I then need to convert them back to degrees to plug into the google mapping portion of my code.
I need to calculate this point so i can display it as the middle of my map so that it will display neatly and centered.
Here is my current code:
开发者_开发百科<?php
ob_start();
?>
<?php
$from = $_POST["from"];
$to = $_POST["to"];
$connection = mysql_connect("localhost", "dlazett", "PASSWORD");
mysql_select_db("dlazett", $connection);
$f = mysql_query ("SELECT * FROM capstone WHERE id = '$from' ",
$connection);
$wfrom = mysql_fetch_array($f);
$latf = $wfrom["lat"];
$lonf = $wfrom["lon"];
$t = mysql_query ("SELECT * FROM capstone WHERE id = '$to' ",
$connection);
$wto = mysql_fetch_array($t);
$latt = $wto["lat"];
$lont = $wto["lon"];
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-…
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:v="urn:schemas-microsoft-com:vml">
<head>
<title>UT Campus Compass</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name = "viewport" content = "width = device-width">
<meta name="apple-mobile-web-app-capable" content="yes" />
<script src="http://maps.google.com/maps?file=ap…
type="text/javascript"></script>
<script type="text/javascript">
function midpoint() {
var lat2 = (<?php echo "$latf";?>) * (Math.PI/180);
var lat1 = (<?php echo "$latt";?>) * (Math.PI/180);
var dLon = (<?php echo "$lonf";?>-<?php echo "$lont";?>) * (Math.PI/180);
var Bx = Math.cos(lat2) * Math.cos(dLon);
var By = Math.cos(lat2) * Math.sin(dLon);
var lat3 = Math.atan2(Math.sin(lat1)+Math.sin(lat2)…
Math.sqrt( (Math.cos(lat1)+Bx)*(Math.cos(lat1)+Bx) + By*By) );
var lon3 = lon1 + Math.atan2(By, Math.cos(lat1) + Bx);
var lat4 = lat3 * (180/Math.PI);
var lon4 = lon3 * (180/Math.PI);
}
function initialize() {
if (GBrowserIsCompatible()) {
var map = new GMap2(document.getElementById("map_canva…
map.setCenter(new GLatLng(lat4, lon4), 16);
var polyline = new GPolyline([
new GLatLng(<?php echo "$latf";?>, <?php echo "$lonf";?>),
new GLatLng(<?php echo "$latt";?>, <?php echo "$lont";?>)
], "#ff0000", 10);
map.addOverlay(polyline);
}
}
</script>
</head>
<body onload="initialize()" onunload="GUnload()">
<center>
<div id="map_canvas" style="width: 425px; height: 600px"></div>
<div id="message"></div>
</body>
</html>
<?php
ob_end_flush();
?>
Any help would be greatly appreciated.
Thanks, Dan
in PHP
function midpoint ($lat1, $lng1, $lat2, $lng2) {
$lat1= deg2rad($lat1);
$lng1= deg2rad($lng1);
$lat2= deg2rad($lat2);
$lng2= deg2rad($lng2);
$dlng = $lng2 - $lng1;
$Bx = cos($lat2) * cos($dlng);
$By = cos($lat2) * sin($dlng);
$lat3 = atan2( sin($lat1)+sin($lat2),
sqrt((cos($lat1)+$Bx)*(cos($lat1)+$Bx) + $By*$By ));
$lng3 = $lng1 + atan2($By, (cos($lat1) + $Bx));
$pi = pi();
return ($lat3*180)/$pi .' '. ($lng3*180)/$pi;
}
function distance($lat1, $lon1, $lat2, $lon2, $unit) {
$theta = $lon1 - $lon2;
$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
$dist = acos($dist);
$dist = rad2deg($dist);
$miles = $dist * 60 * 1.1515;
$unit = strtoupper($unit);
if ($unit == "K") {
return ($miles * 1.609344);
} else if ($unit == "N") {
return ($miles * 0.8684);
} else {
return $miles;
}
}
This function will help you
Use Openlayers and it helps to do this. http://www.openlayers.org/
For a javascript version I converted @vineesh's answer.
function midpoint ($lat1, $lng1, $lat2, $lng2) {
$lat1 = $lat1 * 0.017453292519943295;
$lng1 = $lng1 * 0.017453292519943295;
$lat2 = $lat2 * 0.017453292519943295;
$lng2 = $lng2 * 0.017453292519943295;
$dlng = $lng2 - $lng1;
$Bx = Math.cos($lat2) * Math.cos($dlng);
$By = Math.cos($lat2) * Math.sin($dlng);
$lat3 = Math.atan2( Math.sin($lat1)+Math.sin($lat2),
Math.sqrt((Math.cos($lat1)+$Bx)*(Math.cos($lat1)+$Bx) + $By*$By ));
$lng3 = $lng1 + Math.atan2($By, (Math.cos($lat1) + $Bx));
$pi = 3.141592653589793;
$lat = ($lat3*180)/$pi;
$lng = ($lng3*180)/$pi;
return [$lat,$lng];
}
加载中,请稍侯......
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