使用表达式创建渐变线条
使用表达式创建沿线渐变效果;
<!DOCTYPE html>
<html lang="en">
<head>
<title>使用表达式创建渐变线条</title>
<meta property="og:description" content="使用表达式创建沿线渐变效果" />
<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://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
center: [-77.035, 38.875],
zoom: 12
});
map.on('load', () => {
// 添加包含线条的数据源
map.addSource('line', {
'type': 'geojson',
'lineMetrics': true,
'data': {
'type': 'Feature',
'properties': {},
'geometry': {
'type': 'LineString',
'coordinates': [
[-77.044211, 38.852924],
[-77.045659, 38.860158],
[-77.044232, 38.862326],
[-77.040879, 38.865454],
[-77.039936, 38.867698],
[-77.040338, 38.86943],
[-77.04264, 38.872528],
[-77.03696, 38.878424],
[-77.032309, 38.87937],
[-77.030056, 38.880945],
[-77.027645, 38.881779],
[-77.026946, 38.882645],
[-77.026942, 38.885502],
[-77.028054, 38.887449],
[-77.02806, 38.892088],
[-77.03364, 38.892108],
[-77.033643, 38.899926]
]
}
}
});
// 添加显示渐变线条的图层
map.addLayer({
'id': 'line-gradient',
'type': 'line',
'source': 'line',
'layout': {
'line-cap': 'round',
'line-join': 'round'
},
'paint': {
// 使用表达式创建沿线渐变颜色
// line-progress 属性表示线条上的相对位置(0-1)
'line-color': [
'interpolate',
['linear'],
['line-progress'],
0, 'blue',
0.1, 'royalblue',
0.3, 'cyan',
0.5, 'lime',
0.7, 'yellow',
1, 'red'
],
'line-width': 8,
'line-gradient': [
'interpolate',
['linear'],
['line-progress'],
0, 'blue',
0.1, 'royalblue',
0.3, 'cyan',
0.5, 'lime',
0.7, 'yellow',
1, 'red'
]
}
});
});
</script>
</body>
</html>