从两点lat长旋转div线

Question

如何计算两个城市的方向？

计算两个纬度 - 经度到度和宽度的代码

function getlocationcoords($lat, $lon)
{
    //image amp height and width;
    $height = 1096;
    $width = 543;
    $x = (($lon + 180) * ($width / 360));
    $y = ((($lat * -1) + 90) * ($height / 180)) - 7;
    return array("x" => round($x), "y" => round($y));
}

$latlongfrom = getlocationcoords($cityfrom->latitude, $cityfrom->longitude);
$latlongto = getlocationcoords($cityto->latitude, $cityto->longitude);
$width = hypot($latlongto['y'] - $latlongfrom['y'], $latlongto['x'] - $latlongfrom['x']);
$deg = atan2($latlongto['y'] - $latlongto['y'], $latlongfrom['x'] - $latlongfrom['x']) * 180 / M_PI;

<div class="col-md-12 col-sm-12 col-xs-12" style=" overflow: hidden;">
    <img id="worldmap" src="<?php echo base_url('uploads/worldmap5.png'); ?>" alt="worldmap" title="World map">
    <div class="line" style="width: <?php echo $width ?>px;left: <?php echo $latlongfrom['x'] ?>px;  top: <?php echo $latlongfrom['y'] ?>px;  transform: rotate(<?php echo $deg ?>rad);border-bottom: 5px solid rgb(214, 0, 4); border-top-color: rgb(214, 0, 4); border-right-color: rgb(214, 0, 4); border-left-color: rgb(214, 0, 4); position: absolute; z-index: 1001;"></div>
    ;;
</div>