How can complex polygon coordinates stored in a database be efficiently compared to client-clicked coordinates in PHP?

To efficiently compare complex polygon coordinates stored in a database to client-clicked coordinates in PHP, you can use the point-in-polygon algorithm. This algorithm determines whether a point is inside a polygon by counting how many times a ray cast from the point intersects with the polygon's edges. By implementing this algorithm in PHP, you can accurately determine if a client-clicked point falls within the boundaries of a complex polygon. 

function pointInPolygon($point, $polygon) {
    $x = $point['x'];
    $y = $point['y'];
    $inside = false;
    
    foreach ($polygon as $i => $j) {
        if (($j['y'] > $y) != ($polygon[$i + 1]['y'] > $y) &&
            $x < ($polygon[$i + 1]['x'] - $j['x']) * ($y - $j['y']) / ($polygon[$i + 1]['y'] - $j['y']) + $j['x']) {
            $inside = !$inside;
        }
    }
    
    return $inside;
}

$clickedPoint = ['x' => 5, 'y' => 5];
$polygonCoordinates = [
    ['x' => 0, 'y' => 0],
    ['x' => 10, 'y' => 0],
    ['x' => 10, 'y' => 10],
    ['x' => 0, 'y' => 10]
];

if (pointInPolygon($clickedPoint, $polygonCoordinates)) {
    echo 'Point is inside the polygon';
} else {
    echo 'Point is outside the polygon';
}

Keywords

PHP database polygon coordinates comparison

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