Assignment 9

Using d3-tile to display raster image tiles underneath some TopoJSON vectors, and d3-zoom for pan & zoom. This version reprojects the geometry on interaction; compare to updating the transform. See another variation of this example with points, showing the U.S. State Capitals; also see the static version.

Tiles copyright OpenStreetMap contributors.

forked from mbostock's block: Raster & Vector II

forked from anonymous's block: Raster & Vector II

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  position: absolute;
  margin: 0px;
  font: 16px sans-serif;
  }

body {
  margin: 0;
}

path {
  fill: none;
  stroke: red;
  stroke-linejoin: round;
  stroke-width: 1.5px;
}
/* NEW: style the earthquakes */
path.quake {
  fill: crimson;
}
</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 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");

d3.json("https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json", function(error, us) {
  if (error) throw error;

vector
      .datum(topojson.mesh(us, us.objects.states));

// Compute the projected initial center.
  var center = projection([-98.5, 39.5]);

// 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);

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 "https://" + "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 + ")";
}
var path = d3.geoPath()
    .projection(projection);

// NEW: Read the earthquake data and send it to function "plotQuakes"
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson";

// Topojson for US states
var url = "https://umbcvis.github.io/classes/class-03/us.json"

d3.json(url, plotStates);
d3.json(usgs, plotQuakes);

function plotStates(error, json) {

// Convert topojson to an Array of GeoJSON features
  // This defines "data", a global variable that can be manipulated in the developer console
  data = json.objects.us.geometries.map(function(d) { return topojson.feature(json, d); })

}

// NEW: Function that plots the earthquake data
function plotQuakes(error, json) {
  if (error) return console.log(error);

// Global variable, data, will be visible in the console
  data = json;

// Extract an array of feature objects, one for each earthquake
  var features = json.features;

// Plot the earthquakes
  var layer2 = svg.append("g");

layer2.selectAll("path.quake")
      .data(features)
    .enter().append("path")
      .attr("class", "quake")
      .attr("d", path)
     }
// Add a <div> element to label the mouse position
var info = d3.select("body").append("div")
    .attr("class", "info");
  
  // Label the geographic coordinates of the mouse position on the map
function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), projection.scale()));
}

// Format the text that will be displayed in the the <div> element on the map
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

https://d3js.org/topojson.v1.min.js