Note: This documentation is for the old 0.4.0 version of A-Frame. Check out the documentation for the current 0.5.0 version
HTML is one of the easiest languages to understand, and many of us are already familiar with it. There are no build steps or boilerplate required nor anything to install; all we need is an HTML file:
<a-scene> contains all of the objects in our 3D scene. It also handles all of the setup that is traditionally required for 3D: setting up WebGL, the canvas, camera, lights, renderer, render loop as well as out of the box VR support on platforms such as HTC Vive, Oculus Rift, Samsung GearVR, and smartphones (Google Cardboard). Tons of repeated code eliminated with one clean line of HTML.
Image by Ruben Mueller from The VR Jump.
Then we can place objects within our scene using assorted primitive elements that come with A-Frame such as
<a-sphere>. This is extremely readable, and we could copy and paste this HTML to any other scene and it would behave the same. And we can use the browser’s DOM Inspector just as we would with for any other web site.
Image by Ruben Mueller from The VR Jump.
And being based on the DOM, most existing libraries and frameworks work beautifully on top of A-Frame such as React, Vue.js, d3.js, jQuery, or Angular. The existing web ecosystem of tools were built on top of the notion of manipulating plain HTML and are thus compatible with A-Frame.
A-Frame at its core is an entity-component-system framework. Entity-component-system (ECS) is a pattern popular in game development and is prominent in game engines like Unity. ECS favors composition over inheritance. Every single object in the scene is an entity. An entity is an empty placeholder object that by itself does nothing. We plug in reusable components to attach appearance, behavior, functionality. And we can mix-and-match different components and configure them in order to define different types of objects.
Object-oriented and hierarchical patterns have well-suited the 2D web, where we lay out elements and components that have fixed behavior on a web page. 3D and VR is different; there are infinite types of objects with endless complexity. We need an easy way to build up different kinds of objects without having to create a special class for each one.
In A-Frame, an entity is simply:
Then once defined, we can plug this bundle of appearance, behavior, or functionality into an entity straight from an HTML attribute.
These components are curated and collected into the A-Frame Registry. This is similar to the collection of components and modules on the Unity Asset Store, but free and open source. We make sure they work well and from there they are easily searchable and installable through multiple channels. One of which is through the A-Frame Inspector.
The A-Frame Inspector is a visual tool for inspecting and editing A-Frame scenes. Similar to the browser’s DOM Inspector, you can go to any A-Frame scene, local or on the Web, and hit
<ctrl> + <alt> + i on your keyboard.
This will open the visual Inspector where you can make changes and return to the scene with the reflected changes. You can visually move and place objects, poke around with properties of the components, or pan the camera around to see a different view of the scene. It’s like viewing the source in an interactive way.
The A-Frame Inspector is integrated with the A-Frame Registry. From the Inspector, you can install components from the Registry and attach them to objects in the scene with a couple of clicks.
A-Frame is powerful and performant enough to create compelling experiences. The Mozilla VR team built A-Painter, a room scale Vive experience where you can paint with both of your hands right within the browser. It was built on the order of weeks and runs well at over 90 frames per second.
In the manner of other open source projects such as Rust and Servo, while it is primarily maintained by Mozilla, A-Frame is an open-source community project. We work together to realize the vision of an open, connected, and immersive WebVR platform and ecosystem not owned by any one corporation.
Join us on Slack to hang out or share projects. Check out recent projects that people have been working on in the weekly A-Frame Blog. Ask questions and seek help on Stack Overflow. And if you have something to share, just tweet it @aframevr, and we’ll try to share it. Now let’s get started!