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A-Frame

0.5.0 › Introduction

FAQ

Note: This documentation is for the old 0.5.0 version of A-Frame. Check out the documentation for the current 1.6.0 version

How is A-Frame’s performance?

A-Frame can achieve native-like latency and framerate with proper browsers (e.g., Firefox with WebVR). For example, A-Painter is Tilt Brush in the browser that can smoothly run 90 frames per second and can be indiscernible from native.

A-Frame being based on HTML is not an issue. While the browser’s 2D layout has been a primary performance concern for normal web applications, A-Frame uses Custom Elements to act merely as data containers and does not trigger the layout engine. 3D operations are done in memory with minimal overhead and are rendered with WebGL, which binds to OpenGL or Direct3D.

Some measures that A-Frame takes to minimize overhead include:

  • Making setAttribute synchronous with a reduced code path. Modifying an entity’s position via setAttribute('position', {x: 1, y: 2, z: 3}) almost directly touches the underlying three.js objects. The overhead involves comparing new data to old data to determine whether a change needs to be triggered and invoking lifecycle handlers.
  • Not serializing data back to the DOM. When changing an entity’s properties, the actual HTML as seen in the browser’s DOM inspector is not updated to reduce stringification operations. This makes most operations done in memory, a tiny bit similar to Virtual DOM.
  • Keeping everything under a single requestAnimationFrame and letting components hook into a single global render loop via the tick handler.
  • Caching HTML attributes values.
  • Caching assets, materials, textures, geometries.
  • Providing community components that implement performance techniques used in the 3D and game industry (e.g., geometry instancing, level-of-detail, object pooling).

A-Frame provides reasonable defaults that yield good performance for most common use cases. However, performance is ultimately determined by the complexity and characteristics of each individual application. To get the best use of resources, we will need deeper understanding about 3D graphics. See best performance practices and guidelines to get started.

Why does my asset (e.g., image, video, model) not load?

First, if you are doing local development, make sure you are using a local server so that asset requests work properly.

If you are loading the asset from a different domain, make sure that the asset is served with cross-origin resource sharing (CORS) headers. You could either find a host to serve the asset with CORS headers, or place the asset on the same domain (directory) as your application.

If you are trying to load a video, make sure the browser supports the video (i.e., encoding, framerate, size).

Read the Hosting and Publishing guide for more information.

Why is the HTML not updating when I check the browser inspector?

If you open up your browser’s developer tools, you’ll see that the HTML attribute values are empty.

HTML

To improve performance, A-Frame does not update the HTML to save on stringification operations. Use the debug component or .flushToDOM methods if you need to sync to the DOM.

Why does my video not play on mobile?

Mobile browsers have had limitations playing inline video.

Because of an iOS platform restriction in order to get inline video (with or without autoplay), we must:

  • Set the <meta name="apple-mobile-web-app-capable" content="yes"> meta tag (will be injected if missing).
  • Set the playsinline attribute to the video element (is automatically added to all videos).
  • Possibly pin the webpage to the homescreen for older iOS versions.

Inline video support on iOS 10 may change this. On certain Android devices or browsers, we must:

  • Require user interaction to trigger the video (such as a click or tap event). See Chromium Bug 178297.

Lately, there has been improving support. We do not focus too much on video, but below are GitHub issues that may contain helpful information from community:

How do I display <iframe>s or render HTML in A-Frame?

There is no way for the browser to display <iframe>s within WebGL. While it is possible to overlay an <iframe> on top of the canvas, the <iframe> will not display in VR nor can it integrate with the scene.

Though, we can render basic HTML and CSS as a texture without interactivity. We can paint to a <canvas> and use the canvas as source for a texture. There are components in the ecosystem that enable this:

Which 3D model formats work?

The ideal format is the GL Transmission Format glTF (.gltf) since glTF is feature-rich, compact, and efficient. glTF focuses on providing a transmission format rather than an editor format and is more interoperable with web technologies. Read more about glTF and A-Frame’s glTF component.

COLLADA (.dae) is an XML-based format with a rich feature set. COLLADA is more common in comparison to glTF since it is older, but more suited to native applications that package all their contents together. COLLADA is not recommended since they’re like the .PSD files of 3D models whereas glTF are like the .JPG of 3D models. They’re heavy because they contain complete subscenes.

Wavefront (.obj) is also a well-known format but has some limitations like the lack of animation and vertex color support.

There are also components in the ecosystem for loading other formats:

Below are a couple basic examples for using models:

Where can I find assets?

In general, awesome-stock-resources is a great collection of free assets.

For images, check out textures.com.

For 360° images, search for equirectangular images on Flickr.

For 3D models, check out:

For sounds, check out:

Can I render YouTube videos as a texture?

No. You could proxy YouTube videos as a texture or download them locally to serve, but that is against their terms of service.

Browsers provide the ability to go from WebVR page to WebVR page via the vrdisplayactivate event described in the WebVR specification. Currently, not all browsers implement this. Firefox with WebVR implements this. A link component for link traversal will be released with A-Frame 0.6.0:

<a-entity link="on: click; href: https://aframe-aincraft.glitch.me"></a-entity>

Can I prevent the camera from going through obstacles?

This depends on what devices you plan to support and how you allow users to navigate your scene. For most VR experiences, follow best practices and only move the camera proportionately to the user’s motion.

Don’t block the camera if the user steps forward in a room-scale VR space. For most VR applications it’s better to do locomotion with methods such as using teleportation controls, designing your scene to keep obstacles out of the way or not require much movement, or explore more creative ways of moving users through the world.

For non-VR desktop experiences with a gamepad or keyboard controls or for VR scenes where the camera is inside a vehicle, you can add a physics engine to prevent movement through obstacles.

What type of units does A-Frame use?

A-Frame uses meters with a 1:1 ratio since the WebVR API also uses meters. 5 units in A-Frame is equal to 5 meters in real life. Furthermore, when using programs like Blender, configured in imperial or metric mode, measurements will also translate 1:1. 10 feet in Blender will equal 10 feet in real life.

How is A-Frame different from VRML?

A-Frame is a JavaScript framework. Unlike VRML, A-Frame is not a 3D file format, markup language, nor a standard. A-Frame embraces the Extensible Web Manifesto. Only look at standardization as winning ideas emerge.

Technically, A-Frame is an entity-component-system game engine on top of three.js. As it is a JavaScript framework, coding is to be expected for more complex applications. Unlike 3D file formats, A-Frame provides power and interactivity via full access to JavaScript, three.js, and Web APIs.

Does A-Frame support X feature?

A-Frame ships with a number of components and primitives. Being based on top of an entity-component-system architecture, if a feature doesn’t exist, you can write or find a component to enable it. Or if one of the standard components doesn’t fit your use cases, you can copy and modify it.

Read Where to Find Components for more information.

Does A-Frame support X library or framework?

A-Frame is built on top of the DOM so most libraries and frameworks work including:

Which headsets, browsers, devices, and platforms does A-Frame support?

Most of them. Read VR Headsets and WebVE Browsers for more information.

How can I improve performance?

Read Best Practices — Performance for more information.

How can I get in touch with the A-Frame team?

We try to be responsive and helpful! We love questions, feedback, bug reports, and pull requests:

Where is the roadmap?

The roadmap is on GitHub!

Do I call it “A-Frame” or “aframe” or “aframevr” or “aFrame”?

A-Frame!

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