Assignment 11

<!DOCTYPE html>
<meta charset="utf-8">
<title>LA quakes</title>

<style>

body {
  margin: 0;
}

.map {
  position: relative;
  overflow: hidden;
}

.layer {
  position: absolute;
  will-change: transform;
}

.tile {
  position: absolute;
  width: 256px;
  height: 256px;
}

.tile path {
  fill: none;
  stroke: #000;
  stroke-linejoin: round;
  stroke-linecap: round;
}

.tile .major_road {
  stroke: #776;
}

.tile .minor_road {
  stroke: #ccb;
}

.tile .highway {
  stroke: #f39;
  stroke-width: 1.5px;
}

.tile .rail {
  stroke: #7de;
}

.info {
  position: absolute;
  bottom: 10px;
  left: 10px;
}

</style>
<body>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/d3-tile.v0.0.min.js"></script>
<script>

// Mike Bostock's Vector Tiles https://bl.ocks.org/mbostock/5593150
// Tiles copyright OpenStreetMap contributors (https://www.openstreetmap.org/copyright)

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 path = d3.geoPath()
    .projection(projection);

var tile = d3.tile()
    .size([width, height]);

var zoom = d3.zoom()
    .scaleExtent([1 << 20, 1 << 23])
    .on("zoom", zoomed);

var map = d3.select("body").append("div")
    .attr("class", "map")
    .style("width", width + "px")
    .style("height", height + "px")
    .on("mousemove", mousemoved);

// 1. Add a single SVG for earthquakes
var svg = d3.select("body").append("svg")
    .style("width", width + "px")
    .style("height", height + "px")
    .style('position', 'absolute')
    .style('top', 0)
    .style('left', 0)
    .style('pointer-events', 'none');

var layer = map.append("div")
    .attr("class", "layer");

var info = map.append("div")
    .attr("class", "info");

// Compute the projected initial center.
// 2. Change the location to somewhere interesting
var center = projection([-117, 34]); // LA

// Apply a zoom transform equivalent to projection.{scale,translate,center}.
map .call(zoom)
    .call(zoom.transform, d3.zoomIdentity
        .translate(width / 2, height / 2)
        .scale(1 << 20)
        .translate(-center[0], -center[1]));

// 3. Read and plot the earthquakes (after the projection has been specified)
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson";
var quakes = [];
d3.json(usgs, function(error, usgs) {
  if (error) throw error;
  quakes = usgs.features;

svg.selectAll('.quake')
      .data(quakes)
    .enter().append("path")
      .attr("class", "quake")
      .style("fill", 'crimson')
      .attr('d', path)
});

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]);

// 4. Update earthquake locations on zoom
  svg.selectAll('.quake')
      .attr('d', path);

var image = layer
      .style("transform", stringify(tiles.scale, tiles.translate))
    .selectAll(".tile")
    .data(tiles, function(d) { return d; });

image.exit()
      .each(function(d) { this._xhr.abort(); })
      .remove();

image.enter().append("svg")
      .attr("class", "tile")
      .style("left", function(d) { return d[0] * 256 + "px"; })
      .style("top", function(d) { return d[1] * 256 + "px"; })
      .each(function(d) { this._xhr = render(d, this); });
}

function render(d, node) {
  return d3.json("https://vector.mapzen.com/osm/roads/" + d[2] + "/" + d[0] + "/" + d[1] + ".json?api_key=vector-tiles-LM25tq4", function(error, json) {
    if (error) throw error;
    var k = Math.pow(2, d[2]) * 256; // size of the world in pixels

d3.select(node).selectAll("path")
      .data(json.features.sort(function(a, b) { return a.properties.sort_key - b.properties.sort_key; }))
      .enter().append("path")
        .attr("class", function(d) { return d.properties.kind; })
        .attr("d", d3.geoPath()
            .projection(d3.geoMercator()
                .scale(k / tau)
                .translate([k / 2 - d[0] * 256, k / 2 - d[1] * 256])
                .precision(0)));
  });
}

function stringify(scale, translate) {
  var k = scale / 256, r = scale % 1 ? Number : Math.round;
  return "matrix3d(" + [k, 0, 0, 0, 0, k, 0, 0, 0, 0, k, 0, r(translate[0] * scale), r(translate[1] * scale), 0, 1 ] + ")";
}

function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), d3.zoomTransform(this).k));
}

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>

https://d3js.org/d3.v4.min.js

https://d3js.org/d3-tile.v0.0.min.js