This example shows how to overlay a custom clipped tile layer on top of a Mapbox-gl map. Currently it is not possible to do an arbitrary clip of a mapbox-gl layer, so I’m using d3.geo.tile to overlay raster tiles and clip them using svg clip-paths.
Built with blockbuilder.org
forked from mbostock‘s block: Clipped Map Tiles
forked from enjalot‘s block: Mapbox -> d3 projection
forked from enjalot‘s block: Mapbox-gl + d3.geo.tile + clipping
<!DOCTYPE html>
<head>
<meta charset="utf-8">
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script src="d3.geo.tile.min.js"></script>
<script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.12.0/mapbox-gl.js'></script>
<link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.12.0/mapbox-gl.css' rel='stylesheet' />
<style>
body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
#map {
position:absolute;
width: 100%;
height: 100%;
}
svg {
position: absolute;
width: 100%;
height: 100%;
pointer-events: none;
}
circle.mapbox {
stroke: #111;
fill-opacity: 0.1;
}
circle.d3 {
fill-opacity: 0.1;
stroke-width: 3;
stroke: orange;
}
</style>
</head>
<body>
<div id="map"></div>
<svg id="overlay2"></svg>
<script>
mapboxgl.accessToken = 'pk.eyJ1IjoiZW5qYWxvdCIsImEiOiJjaWhtdmxhNTIwb25zdHBsejk0NGdhODJhIn0.2-F2hS_oTZenAWc0BMf_uw'
//Setup mapbox-gl map
var map = new mapboxgl.Map({
container: 'map', // container id
style: "mapbox://styles/mapbox/light-v9",
center: [-96, 38.3],
zoom: 3,
})
//map.scrollZoom.disable()
map.addControl(new mapboxgl.Navigation());
// Setup our svg layer that we can manipulate with d3
var container = map.getCanvasContainer()
var svg = d3.select(container).append("svg")
// we can project a lonlat coordinate pair using mapbox's built in projection function
function mapboxProjection(lonlat) {
var p = map.project(new mapboxgl.LngLat(lonlat[0], lonlat[1]))
return [p.x, p.y];
}
// we calculate the scale given mapbox state (derived from viewport-mercator-project's code)
// to define a d3 projection
function getD3() {
var bbox = document.body.getBoundingClientRect();
var center = map.getCenter();
var zoom = map.getZoom();
// 512 is hardcoded tile size, might need to be 256 or changed to suit your map config
var scale = (512) * 0.5 / Math.PI * Math.pow(2, zoom);
var d3projection = d3.geo.mercator()
.center([center.lng, center.lat])
.translate([bbox.width/2, bbox.height/2])
.scale(scale);
return d3projection;
}
// calculate the original d3 projection
var d3Projection = getD3();
var tile = d3.geo.tile()
.scale(d3Projection.scale() * 2 * Math.PI)
.translate(d3Projection([0, 0]))
.zoomDelta((window.devicePixelRatio || 1) - .5);
// we want to render the same point
var point = [-96, 38.3]
var mapboxCircle = svg.append("circle").classed("mapbox", true)
var d3Circle = svg.append("circle").classed("d3", true)
var path = d3.geo.path()
.projection(d3Projection)
var clipped = svg.append("g")
.attr("clip-path", "url(#clip)")
d3.json("https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json", function(error, topology) {
if (error) throw error;
var defs = svg.append("defs");
defs.append("path")
.attr("id", "land")
.datum(topojson.feature(topology, topology.objects.land))
.attr("d", path);
defs.append("clipPath")
.attr("id", "clip")
.append("use")
.attr("xlink:href", "#land");
render();
})
function render() {
var bbox = document.body.getBoundingClientRect();
// we update our calculated projections whenever the underlying map changes
// due to zoom and pan
d3Projection = getD3();
// update our tile generator
tile.scale(d3Projection.scale() * 2 * Math.PI)
.translate(d3Projection([0, 0]))
.size([bbox.width, bbox.height])
path.projection(d3Projection)
d3.select("#land").attr("d", path)
mapboxCircle.attr({
cx: mapboxProjection(point)[0],
cy: mapboxProjection(point)[1],
r: 15// * currentScale
})
d3Circle.attr({
cx: d3Projection(point)[0],
cy: d3Projection(point)[1],
r: 25// * currentScale
})
var tiles = tile();
var tiled = clipped.selectAll("image")
.data(tiles, function(d) { return d[2] + "/" + d[0] + "/" + d[1] })
tiled.exit().remove();
tiled.enter().append("image")
.attr("xlink:href", function(d) {
var random = ["a", "b", "c", "d"][Math.random() * 4 | 0];
return "//" + "a" + ".tiles.mapbox.com/v3/mapbox.natural-earth-2/" + d[2] + "/" + d[0] + "/" + d[1] + ".png";
})
tiled
.attr("width", Math.round(tiles.scale))
.attr("height", Math.round(tiles.scale))
.attr("x", function(d) { return Math.round((d[0] + tiles.translate[0]) * tiles.scale); })
.attr("y", function(d) { return Math.round((d[1] + tiles.translate[1]) * tiles.scale); });
}
// re-render our visualization whenever the view changes
map.on("viewreset", function() {
render()
})
map.on("move", function() {
render()
})
// render our initial visualization
render()
</script>
</body>
d3.geo.tile=function(){function t(){var t=Math.max(Math.log(n)/Math.LN2-8,0),h=Math.round(t+e),o=Math.pow(2,t-h+8),u=[(r[0]-n/2)/o,(r[1]-n/2)/o],l=[],c=d3.range(Math.max(0,Math.floor(-u[0])),Math.max(0,Math.ceil(a[0]/o-u[0]))),M=d3.range(Math.max(0,Math.floor(-u[1])),Math.max(0,Math.ceil(a[1]/o-u[1])));return M.forEach(function(t){c.forEach(function(a){l.push([a,t,h])})}),l.translate=u,l.scale=o,l}var a=[960,500],n=256,r=[a[0]/2,a[1]/2],e=0;return t.size=function(n){return arguments.length?(a=n,t):a},t.scale=function(a){return arguments.length?(n=a,t):n},t.translate=function(a){return arguments.length?(r=a,t):r},t.zoomDelta=function(a){return arguments.length?(e=+a,t):e},t};