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@MTClass
Last active April 7, 2017 00:15
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April 6 class
license: mit
<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
margin: 0;
}
.info {
color: #000;
position: absolute;
top: 450px;
left: 800px;
}
path {
fill: none;
stroke: red;
stroke-linejoin: round;
stroke-width: 1.5px;
}
</style>
<svg></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/d3-tile.v0.0.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
var pi = Math.PI,
tau = 2 * pi;
var width = Math.max(960, window.innerWidth),
height = Math.max(500, window.innerHeight);
// Initialize the projection to fit the world in a 1×1 square centered at the origin.
var projection = d3.geoMercator()
.scale(1 / tau)
.translate([0, 0]);
var info = d3.select("body").append("div")
.attr("class", "info");
var path = d3.geoPath()
.projection(projection);
var tile = d3.tile()
.size([width, height]);
var zoom = d3.zoom()
.scaleExtent([1 << 11, 1 << 14])
.on("zoom", zoomed);
var svg = d3.select("svg")
.attr("width", width)
.attr("height", height)
.on("mousemove", mousemoved);
var raster = svg.append("g");
var vector = svg.append("path");
var quakes = svg.append("g")
var us = "https://umbcvis.github.io/classes/class-03/us.json";
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson";
d3.queue()
.defer(d3.json, us)
.defer(d3.json, usgs)
.await(ready);
function ready(error, us, usgs) {
if (error) throw error;
vector
.datum(topojson.mesh(us, us.objects.us));
// Compute the projected initial center.
var center = projection([-98.5, 39.5]);
quakes = quakes.selectAll(".quake")
.data(usgs.features)
.enter().append('path')
.attr('class', 'quake')
.attr('d', path)
.style('fill', 'crimson')
// Apply a zoom transform equivalent to projection.{scale,translate,center}.
svg
.call(zoom)
.call(zoom.transform, d3.zoomIdentity
.translate(width / 2, height / 2)
.scale(1 << 12)
.translate(-center[0], -center[1]));
}
function zoomed() {
var transform = d3.event.transform;
var tiles = tile
.scale(transform.k)
.translate([transform.x, transform.y])
();
projection
.scale(transform.k / tau)
.translate([transform.x, transform.y]);
vector
.attr("d", path);
quakes.attr("d", path);
var image = raster
.attr("transform", stringify(tiles.scale, tiles.translate))
.selectAll("image")
.data(tiles, function(d) { return d; });
image.exit().remove();
image.enter().append("image")
.attr("xlink:href", function(d) { return "http://" + "abc"[d[1] % 3] + ".tile.openstreetmap.org/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })
.attr("x", function(d) { return d[0] * 256; })
.attr("y", function(d) { return d[1] * 256; })
.attr("width", 256)
.attr("height", 256);
}
function stringify(scale, translate) {
var k = scale / 256, r = scale % 1 ? Number : Math.round;
return "translate(" + r(translate[0] * scale) + "," + r(translate[1] * scale) + ") scale(" + k + ")";
}
function mousemoved() {
info.text(formatLocation(projection.invert(d3.mouse(this)), projection.scale()));
}
function formatLocation(p, k) {
var format = d3.format("." + Math.floor(Math.log(k) / 2 - 2) + "f");
return (p[1] < 0 ? format(-p[1]) + "°S" : format(p[1]) + "°N") + " "
+ (p[0] < 0 ? format(-p[0]) + "°W" : format(p[0]) + "°E");
}
</script>
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