Globe Mixins

The underlying globe object is based on Cesium.

Base Globe

DANGER

This mixin is a mandatory one to build a globe activity

Make it possible to manage globe layers and extend supported layer types:

• setupGlobe(domElement, token, options) creates the underlying Cesium globe object with given Cesium Ion token and viewer options
• addLayer(options)/removeLayer(name) registers/destroys a layer based on a catalog layer descriptor
• showLayer/hideLayer(name) (un)hides the given layer in globe, on first show the layer will be lazily created
• hasLayer(name) check if a given layer is already registered
• isLayerVisible(name) check if a given layer is visible and underlying Cesium object created
• zoomToLayer(name) fits the globe view to visualize a given layer
• zoomToBounds(bounds) fits the globe view to visualize a given extent as bounds [ [south, west], [north, east] ]
• getLayerByName(name) retrieve the catalog layer descriptor for a given layer
• renameLayer(previousName, newName) rename a given layer
• removeLayer(name) destroys a given layer
• getCesiumLayerByName(name) retrieve the underlying Cesium object for a given layer
• createCesiumLayer(options) creates the underlying Cesium object based on a catalog layer descriptor, will check all registered constructor for any one matching
• registerCesiumConstructor(constructor) registers a Cesium constructor function for a given type of layer
• center(longitude, latitude, altitude, heading, pitch, roll, options) centers the globe view to visualize a given point at a given altitude with and orientation (default is pointing ground vertically [0, 0, -90]), some options like an animation duration can also be added
• getCenter() get the current globe view center as longitude, latitude and altitude
• getBounds() get the current map view bounds as [ [south, west], [north, east] ]

This mixin also adds the following internal data properties:

• layers available layers as catalog layer descriptors

Globe Style

Make it possible to setup Cesium entities objects with style based on (Geo)Json (feature) properties stored in entities:

• convertFromSimpleStyleSpec(style) helper function to convert from simple style spec options to Cesium style options
• convertToCesiumObjects(style) helper function to convert from JSON description to Cesium objects

Use register/unregisterStyle(type, generator) to (un)register a function generating a Cesium object depending on the given type:

• entityStyle => f(entity, options) returns a Cesium entity style object
• clusterStyle => f(entities, cluster, options) returns a Cesium cluster style object

The mixin automatically registers defaults styling:

• entityStyle => will create a style based on the following options merged with the following order of precedence
  • simple style spec options set on feature.style or feature.properties
  • Cesium entity style options set on layer descriptor
  • Cesium entity style options set on the entityStyle property in the component options
• clusterStyle => will create a style based on the following options merged with the following order of precedence
  • Cesium cluster style options set on layer descriptor
  • Cesium cluster style options set on the clusterStyle property in the component options

Cesium styles often rely on dynamically created objects while the input styling configuration is a static JSON. As a consequence the following rules are used to convert from JSON to Cesium objects:

• constants are expressed as strings starting with 'Cesium.'
• object instances are expressed as a { type, options } object where type is a string starting with 'Cesium.' followed by the class name like 'Cesium.CheckerboardMaterialProperty', options are constructor options for the object instance The following Cesium code:

ellipse.material = new Cesium.CheckerboardMaterialProperty({
  evenColor : Cesium.Color.WHITE,
  oddColor : Cesium.Color.BLACK,
  repeat : new Cesium.Cartesian2(4, 4)
})

will result in the following Json configuration:

ellipse: {
  material: {
    type: 'Cesium.CheckerboardMaterialProperty',
    options: {
      evenColor: 'Cesium.Color.WHITE',
      oddColor: 'Cesium.Color.BLACK',
      repeat: {
        type: 'Cesium.Cartesian2',
        options: [4, 4]
    }
  }
}

Globe Popup

Make it possible to generate Cesium labels as popups based on GeoJson feature properties stored in entities. Use register/unregisterStyle(popup, generator) to (un)register a function f(entity, options) returning a Cesium entity style object

The mixin automatically registers a default generator that will create a popup displaying a property name/value table based on the following options with the following order of precedence

• popup: set on entity.properties or layer descriptor or in the popup property of component options
  • pick: array of property names to appear in the popup
  • omit: array of property names not to appear in the popup
  • template: Lodash template to generate popup content with feature, its properties and translation function $t as context
  • html: HTML content of the popup, if provided will override default display
  • options: Cesium label options

TIP

If you want to disable a default popup configuration like popup: { } (i.e. display all properties) on a per-layer basis you have to explicitely unset it on your layer options using popup: null or popup: false.

Globe Tooltip

Make it possible to generate Cesium labels as tooltips based on GeoJson feature properties stored in entities. Use register/unregisterStyle(tooltip, generator) to (un)register a function f(entity, options) returning a Cesium entity style object

The mixin automatically registers a default generator that will create a tooltip based on the following options with the following order of precedence

• tooltip: set on entity.properties or layer descriptor or in the tooltip property of component options
  • property: property name to appear in the tooltip
  • template: Lodash template to generate tooltip content with feature, its properties and translation function $t as context
  • html: HTML content of the tooltip, if provided will override default display
  • options: Cesium label options

TIP

If you want to disable a default tooltip configuration like tooltip: { property: 'name' } (i.e. display all properties) on a per-layer basis you have to explicitely unset it on your layer options using tooltip: null or tooltip: false.

GeoJson Layer

Make it possible to manage and style raw or time-based GeoJson map layers:

• createCesiumGeoJsonLayer(options) automatically registered GeoJson Cesium layer constructor
• updateLayer(name, geoJson) update underlying GeoJson data of a given layer

DANGER

The style mixin is mandatory when using this mixin. If you'd like to support popups/tooltips you should also use the popup mixin and/or tooltip mixin.

TIP

Marker cluster options are to be provided in the cluster property of the Cesium layer options

The following configuration illustrates a GeoJson marker cluster layer using options set on the layer descriptor (see image below):

{
  name: 'Layer',
  description: 'My sites',
  tags: [ 'business' ],
  icon: 'star',
  attribution: '(c) My company',
  type: 'OverlayLayer',
  cesium: {
    type: 'geoJson',
    source: 'https://s3.eu-central-1.amazonaws.com/kargo/nuclear-sites.json',
    cluster: {
      pixelRange: 50
    },
    'marker-symbol': 'star',
    'marker-color': '#FFA500'
  }
}

Additional feature types

The following options can be set as feature properties to manage more geometry types:

• wall boolean set to true on a LineString will result in an additional WallGraphics, which uses the styling options of the feature
• geodesic boolean set to true on a Point will result in a great circle represented as a EllipseGraphics, which radius must be specified in meters and uses the styling options of the feature
• icon-text string set on a Point will result in a LabelGraphics instead of a BillboardGraphics, which uses the styling options of the feature

Dynamic styling

The same than for dynamic map style applies for globe. Note however that templating will be applied once the 3D entities have been created, which means that you cannot use templating on simple style spec options but rather on Cesium object options set on the entityStyle layer option.

For instance you can change the marker color or image based on a given features's property like this:

entityStyle: {
  billboard: {
    image: `<% if (properties.visibility < 75) { %>/statics/windyblack.png<% }
              else if (properties.visibility < 300) { %>/statics/windyred.png<% }
              else if (properties.visibility < 1500) { %>/statics/windyorange.png<% }
              else if (properties.visibility < 3000) { %>/statics/windyyellow.png<% }
              else { %>/statics/windygreen.png<% } %>`,
    color: `Cesium.Color.<% if (properties.visibility < 75) { %>BLACK<% }
              else if (properties.visibility < 300) { %>ORANGERED<% }
              else if (properties.visibility < 1500) { %>GOLD<% }
              else if (properties.visibility < 3000) { %>YELLOW<% }
              else { %>LIMEGREEN<% } %>"/>`
  },
  template: ['billboard.image', 'billboard.color']
}

You can also draw a path with a different styling on each part like this:

{
  type: 'FeatureCollection',
  features: [{
    type: 'Feature',
    properties: { stroke: '#000000', weight: 1 },
    geometry: { type: 'LineString', coordinates: [...] }
  }, {
    type: 'Feature',
    properties: { stroke: '#FF00FF', weight: 3 },
    geometry: { type: 'LineString', coordinates: [...] }
  }]
}

File Layer

Make it possible to drag'n'drop GeoJson or KML file on the globe. It will automatically create a new GeoJson layer named after the filename on drop. As a consequence it has to be used with the GeoJson layer mixin and will use the configured styling.

Globe Activity

Make it easier to create 3D mapping activities:

• initializeGlobe(token) setup the render engine with given Cesium ion access token, should be called first before any other method
• finalizeGlobe() destroy the render engine

DANGER

It assumes that the DOM element used by the render engine has a ref named globe