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Change building color based on zoom level

Use the interpolate expression to ease-in the building layer and smoothly fade from one color to the next.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Change building color based on zoom level</title>
    <meta property="og:description" content="Use the interpolate expression to ease-in the building layer and smoothly fade from one color to the next." />
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <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: 100%; }
        #zoom {
            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>
</head>
<body>
<div id="map"></div>
<button id="zoom">Zoom to buildings</button>
<script>
    const map = new trackasiagl.Map({
        container: 'map',
        style: 'https://maps.track-asia.com/styles/v1/streets.json?key=public_key',
        center: {"lat":10.762622,"lng":106.660172},
        zoom: 11
    });

    map.on('load', () => {
        map.setPaintProperty('building', 'fill-color', [
            'interpolate',
            ['exponential', 0.5],
            ['zoom'],
            15,
            '#e2714b',
            22,
            '#eee695'
        ]);

        map.setPaintProperty('building', 'fill-opacity', [
            'interpolate',
            ['exponential', 0.5],
            ['zoom'],
            15,
            0,
            22,
            1
        ]);
    });

    document.getElementById('zoom').addEventListener('click', () => {
        map.zoomTo(16, {duration: 9000});
    });
</script>

</body>
</html>