# Planetary.js: Awesome interactive globes for the web

# Rotating Globe with Pings

This code shows the example from the homepage, which rotates, shows randomly positioned, colored, and sized pings on the globe, and supports mouse-based dragging and zooming. It also shows the creation and use of a plugin, which powers the automatic rotation and exposes a public API.

We're using a specially-made TopoJSON file that includes lake data so that we can draw lakes on the globe with a custom plugin, which you can find at the bottom of the JavaScript. The custom TopoJSON was made using the TopoJSON command-line tool and data from Natural Earth; you can also download the JSON file for your own use.

The demo also shows how you can keep your globe from looking pixelated on high density displays by changing the canvas' width and height but keeping its displayed width and height the same via CSS styling.

HTML

    <canvas id='basicGlobe' width='400' height='400'
      style='width: 400px; height: 400px; cursor: move;'></canvas>

JavaScript

    (function() {
      var globe = planetaryjs.planet();
      // Load our custom `autorotate` plugin; see below.
      globe.loadPlugin(autorotate(10));
      // The `earth` plugin draws the oceans and the land; it's actually
      // a combination of several separate built-in plugins.
      //
      // Note that we're loading a special TopoJSON file
      // (world-110m-withlakes.json) so we can render lakes.
      globe.loadPlugin(planetaryjs.plugins.earth({
        topojson: { file:   '/world-110m-withlakes.json' },
        oceans:   { fill:   '#000080' },
        land:     { fill:   '#339966' },
        borders:  { stroke: '#008000' }
      }));
      // Load our custom `lakes` plugin to draw lakes; see below.
      globe.loadPlugin(lakes({
        fill: '#000080'
      }));
      // The `pings` plugin draws animated pings on the globe.
      globe.loadPlugin(planetaryjs.plugins.pings());
      // The `zoom` and `drag` plugins enable
      // manipulating the globe with the mouse.
      globe.loadPlugin(planetaryjs.plugins.zoom({
        scaleExtent: [100, 300]
      }));
      globe.loadPlugin(planetaryjs.plugins.drag({
        // Dragging the globe should pause the
        // automatic rotation until we release the mouse.
        onDragStart: function() {
          this.plugins.autorotate.pause();
        },
        onDragEnd: function() {
          this.plugins.autorotate.resume();
        }
      }));
      // Set up the globe's initial scale, offset, and rotation.
      globe.projection.scale(175).translate([175, 175]).rotate([0, -10, 0]);

      // Every few hundred milliseconds, we'll draw another random ping.
      var colors = ['red', 'yellow', 'white', 'orange', 'green', 'cyan', 'pink'];
      setInterval(function() {
        var lat = Math.random() * 170 - 85;
        var lng = Math.random() * 360 - 180;
        var color = colors[Math.floor(Math.random() * colors.length)];
        globe.plugins.pings.add(lng, lat, { color: color, ttl: 2000, angle: Math.random() * 10 });
      }, 250);

      var canvas = document.getElementById('rotatingGlobe');
      // Special code to handle high-density displays (e.g. retina, some phones)
      // In the future, Planetary.js will handle this by itself (or via a plugin).
      if (window.devicePixelRatio == 2) {
        canvas.width = 800;
        canvas.height = 800;
        context = canvas.getContext('2d');
        context.scale(2, 2);
      }
      // Draw that globe!
      globe.draw(canvas);

      // This plugin will automatically rotate the globe around its vertical
      // axis a configured number of degrees every second.
      function autorotate(degPerSec) {
        // Planetary.js plugins are functions that take a `planet` instance
        // as an argument...
        return function(planet) {
          var lastTick = null;
          var paused = false;
          planet.plugins.autorotate = {
            pause:  function() { paused = true;  },
            resume: function() { paused = false; }
          };
          // ...and configure hooks into certain pieces of its lifecycle.
          planet.onDraw(function() {
            if (paused || !lastTick) {
              lastTick = new Date();
            } else {
              var now = new Date();
              var delta = now - lastTick;
              // This plugin uses the built-in projection (provided by D3)
              // to rotate the globe each time we draw it.
              var rotation = planet.projection.rotate();
              rotation[0] += degPerSec * delta / 1000;
              if (rotation[0] >= 180) rotation[0] -= 360;
              planet.projection.rotate(rotation);
              lastTick = now;
            }
          });
        };
      };

      // This plugin takes lake data from the special
      // TopoJSON we're loading and draws them on the map.
      function lakes(options) {
        options = options || {};
        var lakes = null;

        return function(planet) {
          planet.onInit(function() {
            // We can access the data loaded from the TopoJSON plugin
            // on its namespace on `planet.plugins`. We're loading a custom
            // TopoJSON file with an object called "ne_110m_lakes".
            var world = planet.plugins.topojson.world;
            lakes = topojson.feature(world, world.objects.ne_110m_lakes);
          });

          planet.onDraw(function() {
            planet.withSavedContext(function(context) {
              context.beginPath();
              planet.path.context(context)(lakes);
              context.fillStyle = options.fill || 'black';
              context.fill();
            });
          });
        };
      };
    })();