block by pnavarrc 582ef07fe7974ef59deb

Map Zoom and Rotate

Full Screen

index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <title>Zoom and Rotating (Reprojecting)</title>

  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js"></script>
</head>
<body>

  <style>
  body {
    margin: 0;
  }

  svg {
    background-color: #333;
  }

  .sphere {
    fill: #A7DBD8;
    stroke: #79A09E;
  }

  .land {
    fill: #E0E4CC;
    stroke: #ACAF9F;
    stroke-width: 1;
  }

  .graticule {
    fill: none;
    stroke: #79A09E;
    stroke-width: 1;
    stroke-dasharray: 1,2;
  }

  .overlay {
    fill-opacity: 0;
  }
  </style>

  <div id="map-container"></div>

  <script>

    // Set the dimensions of the map
    var width  = 960,
        height = 480;

    var state = {
      x: 0,
      y: 0,
      scale: height / 2
    };

    // Create a selection for the container div and append the svg element
    var div = d3.select('#map-container'),
        svg = div.append('svg');

    // Set the size of the SVG element
    svg.attr('width', width).attr('height', height);

    // Create and configure a geographic projection
    var projection = d3.geo.orthographic()
      .scale(state.scale)
      .clipAngle(90)
      .translate([width / 2, height / 2]);

    // Create and configure a path generator
    var pathGenerator = d3.geo.path()
      .projection(projection);

    // Create and configure the graticule generator (one line every 20 degrees)
    var graticule = d3.geo.graticule();

    // Retrieve the geographic data asynchronously
    d3.json('countries.geojson', function(err, data) {

      // Throw errors on getting or parsing the file
      if (err) { throw err; }

      // Create a group to hold the map-related features
      var grp = svg.selectAll('g.container').data([data]);

      grp.enter().append('g').classed('container', true);
      grp.exit().remove();

      // Shpere (map boundaries)
      var sphere = grp.selectAll('path.sphere').data([{type: 'Sphere'}]);

      sphere.enter().append('path').classed('sphere', true);
      sphere.attr('d', pathGenerator);
      sphere.exit().remove();

      // Graticule lines (behind the land)
      var lines = grp.selectAll('path.graticule').data([graticule()]);

      lines.enter().append('path').classed('graticule', true);
      lines.attr('d', pathGenerator);
      lines.exit().remove();

      // Land
      var land = grp.selectAll('path.land').data([data]);

      land.enter().append('path').classed('land', true);
      land.attr('d', pathGenerator);
      land.exit().remove();

      // Create and configure the zoom behaviour
      var zoomBehavior = d3.behavior.zoom()
        .on('zoom', function() {

          // Get the scale and translation information from the zoom event
          var scale = d3.event.scale,
              dx = d3.event.translate[0],
              dy = d3.event.translate[1];

          // Update the rotation and scale state
          state.scale = state.scale * scale;
          state.x += 180 / width * dx;
          state.y += -180 / height * dy;

          // Update the projection scale and rotation
          projection
            .scale(state.scale)
            .rotate([state.x, state.y]);

          // Update the paths
          svg.selectAll('path')
            .attr('d', pathGenerator);
        });

      // Bind the zoom behaviour to the SVG container
      svg.call(zoomBehavior);

    });
  </script>

</body>
</html>

Makefile

# Download and Transform the 1:50m Country Shapefiles from Natural Earth
# http://www.naturalearthdata.com/downloads/50m-cultural-vectors/

URL = http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/50m/cultural/ne_50m_admin_0_countries.zip

# Download the zip file from the Natural Earth server
ne_50m_admin_0_countries.zip:
	curl -LO $(URL)

# Unzip the shapefiles
ne_50m_admin_0_countries.shp: ne_50m_admin_0_countries.zip
	unzip ne_50m_admin_0_countries.zip
	touch ne_50m_admin_0_countries.shp

# Convert the shapefiles to GeoJSON
countries.geojson: ne_50m_admin_0_countries.shp
	ogr2ogr -f GeoJSON countries.geojson ne_50m_admin_0_countries.shp

# Convert the GeoJSON file to TopoJSON
countries.topojson: countries.geojson
	topojson -p -o countries.topojson countries.geojson

# Remove source and temporary files
clean:
	rm ne_50m_admin_0_countries*