Phóng to quả địa cầu với chức năng kích thước hành tinh

Phóng to quả địa cầu với chức năng kích thước hành tinh.
<!DOCTYPE html>
<html lang="en">
<head>
    <title>Zoom and planet size relation on globe</title>
    <meta property="og:description" content="Explanation of zoom and planet size relation under globe projection and how to account for it when changing the map center and zoom by some delta." />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/[email protected]/dist/trackasia-gl.css' />
    <script src='https://unpkg.com/[email protected]/dist/trackasia-gl.js'></script>
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 99%; }
    </style>
</head>
<body>
<style>
    #fly {
        display: block;
        position: absolute;
        top: 20px;
        left: 50%;
        transform: translate(-50%);
        width: 50%;
        height: 40px;
        padding: 10px;
        border: none;
        border-radius: 3px;
        font-size: 12px;
        text-align: center;
        color: #fff;
        background: #ee8a65;
    }
</style>
<div id="map"></div>
<br />
<button id="fly">Go to pole or equator</button>
<script>
    const map = new trackasiagl.Map({
        container: 'map',
        style: 'https://static.track-asia.com/demotiles/style.json',
        center: [0, 0],
        zoom: 2,
    });

    map.on('style.load', () => {
        map.setProjection({
            type: 'globe', // Set projection to globe
        });
    });

    // To stay consistent with web mercator maps, globe is automatically enlarged when map center is nearing the poles.
    // This keeps the map center visually similar to a mercator map with the same x,y and zoom.
    // However, sometimes we want to negate this effect and keep the globe size consistent even when changing latitudes.
    // This function computes what we need to add the the target zoom level when changing latitude.
    function getZoomAdjustment(oldLatitude, newLatitude) {
        return Math.log2(Math.cos(newLatitude / 180 * Math.PI) / Math.cos(oldLatitude / 180 * Math.PI));
    }

    // Switch back and forth between zooming in and out.
    let zoomIn = false;
    const zoomDelta = 1.5;

    document.getElementById('fly').addEventListener('click', () => {
        // Fly to a random location by offsetting the point -74.50, 40
        // by up to 5 degrees.
        const center = [
            map.getCenter().lng,
            zoomIn ? 0 : 80,
        ];
        const mapZoom = map.getZoom();
        const delta = (zoomIn ? zoomDelta : -zoomDelta);
        // We want to change the map's globe size by some delta and change the center latitude at the same time,
        // thus we need to compensate for the globe enlarging effect described earlier.
        const zoom = map.getZoom() + delta + getZoomAdjustment(map.getCenter().lat, center[1]);
        map.flyTo({
            center,
            zoom,
            essential: true // this animation is considered essential with respect to prefers-reduced-motion
        });
        zoomIn = !zoomIn;
    });
</script>
</body>
</html>