Plugins

Planetary.js uses a plugin-based architecture, and all the built-in functionality is built using this architecture. This makes Planetary.js extremely flexible.

Loading Plugins

Plugins are loaded either globally by planetaryjs.loadPlugin or for a specific planet instance by planet.loadPlugin. If you call draw on a planet and it has no plugins loaded at all (from either source), Planetary.js will use the default plugin stack, which consists of the earth and pings plugins.

Anatomy of a Plugin

A plugin is simply a JavaScript function that takes a planet instance as a parameter and performs some predefined operation. The best plugins do one tiny thing. If you want a plugin to do a lot of things at once, you should build a plugin that wraps other, smaller plugins; in fact, this is exactly how the earth plugin is built. See the Earth documentation for more details.

Most of the time, a plugin will implement its behavior by registering callbacks into the planet's lifecycle hooks. For example, the following simple plugin increments the planet's projection's rotation by one degree every tick (this would make for a very fast spinning globe, but demonstrates the idea nicely enough):

var autorotate = function(planet) {
  planet.onDraw(function() {
    var rotation = planet.projection.rotate();
    rotation[0] += 1;
    if (rotation[0] >= 180) rotation[0] -= 360;
    planet.projection.rotate(rotation);
  });
};

planet.loadPlugin(autorotate);

Plugin Generators

Often, you'll want your plugin to be configurable with some user-defined values. You can create a function generator, which is a function that takes your configuration data and then returns the plugin function. You can then call this generator to generate the plugin function for use by loadPlugin.

var autorotate = function(degreesPerTick) {
  return function(planet) {
    planet.onDraw(function() {
      var rotation = planet.projection.rotate();
      rotation[0] += degreesPerTick;
      if (rotation[0] >= 180) rotation[0] -= 360;
      planet.projection.rotate(rotation);
    });
  };
};

planet.loadPlugin(autorotate(5));