绕点相机动画

使相机绕着一个点旋转动画;

<!DOCTYPE html>
<html lang="en">
<head>
    <title>绕点相机动画</title>
    <meta property="og:description" content="使相机绕着一个点旋转动画" />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/maplibre-gl@5.5.0/dist/maplibre-gl.css' />
    <script src='https://unpkg.com/maplibre-gl@5.5.0/dist/maplibre-gl.js'></script>
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
    </style>
</head>
<body>
<div id="map"></div>
<script>
    const map = new maplibregl.Map({
        container: 'map',
        style:
            'https://demotiles.maplibre.org/styles/osm-bright-gl-style/style.json',
        center: [-87.62712, 41.89033],
        zoom: 15.5,
        pitch: 45
    });

    function rotateCamera(timestamp) {
        // 将旋转限制在0-360度之间
        // 将timestamp除以100来减慢旋转速度到大约每秒10度
        map.rotateTo((timestamp / 100) % 360, {duration: 0});
        // 请求动画的下一帧
        requestAnimationFrame(rotateCamera);
    }

    map.on('load', () => {
        // 开始动画
        rotateCamera(0);

        // 添加3D建筑并移除标签图层以增强地图效果
        const layers = map.getStyle().layers;
        for (let i = 0; i < layers.length; i++) {
            if (layers[i].type === 'symbol' && layers[i].layout['text-field']) {
                // 移除文本标签
                map.removeLayer(layers[i].id);
            }
        }

        map.addLayer({
            'id': '3d-buildings',
            'source': 'composite',
            'source-layer': 'building',
            'filter': ['==', 'extrude', 'true'],
            'type': 'fill-extrusion',
            'minzoom': 15,
            'paint': {
                'fill-extrusion-color': '#aaa',

                // 使用'interpolate'表达式添加平滑过渡效果
                // 当用户放大时建筑物会逐渐显示
                'fill-extrusion-height': [
                    'interpolate',
                    ['linear'],
                    ['zoom'],
                    15,
                    0,
                    15.05,
                    ['get', 'height']
                ],
                'fill-extrusion-base': [
                    'interpolate',
                    ['linear'],
                    ['zoom'],
                    15,
                    0,
                    15.05,
                    ['get', 'min_height']
                ],
                'fill-extrusion-opacity': 0.6
            }
        });
    });
</script>
</body>
</html>