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argon.js

argon.js

An open-standards augmented reality platform for the web

This software was created as part of a research project at the Augmented Environments Lab at Georgia Tech. To support our research, we request that if you make use of this software, you let us know how you used it by sending mail to Blair MacIntyre (blair@cc.gatech.edu).

API

There are essentially 3 types of systems that are defined by the argon.js framework:

  • [[REALITY_AUGMENTOR]] - a system that is responsible for augmenting a view of reality.
  • [[REALITY_VIEW]] - a system that is responsible for presenting a view of reality
  • [[REALITY_MANAGER]] - a system that is responsible for blending a particular Reality View with one or more Reality Augmentors

Traditionally, Augmented Reality (AR) apps have had to take on all three of these roles at once. However, by separating these concerns out, each role can be easily swapped out with another implmentation, allowing for a much more flexible and adaptive AR application ecosystem.

The argon.js framework also anticipates a future in which AR-enabled browsers (functioning as a Reality Manager) may give users control over the way they interact with AR content, and let the user (not the applications) control how they are displayed by allowing the user to change their view of reality. For example, a user may want to switch from live video, to remote video, to a virtual flyover of their—all while an AR application is running. Similarly, in these future browsers, users may want to run multiple AR applications simultaneously, and different application requirements may cause the browser to use different views of reality for the different applications. We are exploring these ideas within the Argon browser (which already allows multiple apps to run and be visible at the same time, for example), and these use-cases have informed the design of argon.js.

The structure of an AR-enabled app

In general, we simply call init to initailize our app:

var app = Argon.init();

Note: By default, this will initialize your app with a role appropriate for the environment in which it is executing. If your app is running within a Reality Manager such as the Argon Browser, then it will be initialized with the role of a Reality Augmentor. If your app is running in a standalone manner, then it will be elevated to the role of a Reality Manager. In general, this detail does not affect the way you write your app, as argon.js includes default implementations of the responsbilities of a Reality Manager. However, if your app detects that it is running as a Reality Manager, it may assume more control over the entire experience.

The object returned by init is an instance of ArgonSystem. By convention, we store this instance in a variable called app. Various services are made available via this instance. For example, your app will need to continually respond to changes in the world in order to update it's augmentations. ArgonSystem.updateEvent let's you setup a callback for that purpose:

app.updateEvent.addEventListener(function (){
    // update our augmentations
})

In argon.js, all objects are represented in geospatial coordinates, using cesium.js Entities (a subset of Cesium's API is availabe in the Argon.Cesium namespace). ArgonSystem.context exposes a ContextService instance whose purpose is to keep track of entities that you can augment, or subscribe to new entities so that your app can be made aware of them. Via the ContextService.getEntityPose method, you can convert an Entity from geospatial coordinates into your local scenegraph coordinates.

In your update event handler, you can, for example, query the current pose of an Entity by calling ContextService.getEntityPose and passing the desired entity instance.

Finally, we can listen to the render event in order to render our augmentations in a timely manner:

app.renderEvent.addEventListener(function (){
    // render our augmentations
})

argon.js is itself entirely decoupled from any particular rendering library, but does aim to provide a level of abstraction that makes it easy to integrate with the library of your choice.

Check out the tutorials for more concrete examples of argon.js AR-enabled apps.

The structure of a Reality View

TODO

The structure of a Reality Manager

TODO

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