Tutorial by Examples: r

The core idea is to use GameObjects to represent singletons, which has multiple advantages: Keeps complexity to a minimum but supports concepts like dependency injection Singletons have a normal Unity lifecycle as part of the Entity-Component system Singletons can be lazy loaded and cached loca...

We can use the componentchanged event to listen for changes to the entity: entity.addEventListener('componentchanged', function (evt) { if (evt.detail.name === 'position') { console.log('Entity has moved from', evt.detail.oldData, 'to', evt.detail.newData, '!'); } });

We can use the child-attached and child-detached events to listen for when the scene attaches or detaches an entity: entity.addEventListener('child-attached', function (evt) { if (evt.detail.el.tagName.toLowerCase() === 'a-box') { console.log('a box element has been attached'); }; }); ...

Updating Multi-Property Component Data To update component data for a multi-property component, we can pass the name of a registered component as the componentName, and pass an object of properties as the value. A string is also acceptable (e.g., type: spot; distance: 30), but objects will save A-F...

We can simply retrieve an entity using DOM APIs. <a-entity id="mario"></a-entity> var el = document.querySelector('#mario');

For example, if we wanted to grab an entity’s three.js camera object or material object, we could reach into its components var camera = document.querySelector('a-entity[camera]').components.camera.camera; var material = document.querySelector('a-entity[material]').components.material.material; ...

A system is registered similarly to a A-Frame component. If the system name matches a component name, then the component will have a reference to the system as this.system: AFRAME.registerSystem('my-component', { schema: {}, // System schema. Parses into `this.data`. init: function () { ...

Systems can help separate logic and behavior from data if desired. We let systems handle the heavy lifting, and components only worry about managing its data through its lifecycle methods: AFRAME.registerSystem('my-component', { createComplexObject: function (data) { // Do calculations ...

There is no strict API for defining how systems manage components. A common pattern is to have components subscribe themselves to the system. The system then has references to all of its components: AFRAME.registerSystem('my-component', { init: function () { this.entities = []; }, ...

AFRAME.registerComponent (name, definition) Register an A-Frame component. We must register components before we use them anywhere in . Meaning from an HTML file, components should come in order before . {string} name - Component name. The component’s public API as represented through an HTML at...

A component holds a bucket of data in the form of one or more component properties. Components use this data to modify entities. Consider an engine component, we might define properties such as horsepower or cylinders. HTML attributes represent component names and the value of those attributes repr...

Property types primarily define how the schema parses incoming data from the DOM for each property. The parsed data will then be available via the data property on the component's prototype. Below are A-Frame's built-in property types: Property TypeDescriptionDefault ValuearrayParses comma-separ...

A component’s members and methods can be accessed through the entity from the .components object. Look up the component from the entity’s map of components, and we’ll have access to the component’s internals. Consider this example component: AFRAME.registerComponent('foo', { init: function () { ...

Since A-Frame fetches assets using XHRs, browser security requires the browser to serve assets with cross-origin resource sharing (CORS) headers if the asset is on a different domain. Otherwise, we'd have to host assets on the same origin as the scene. For some options, GitHub Pages serves every...

Audio and video assets will only block the scene if we set autoplay or if we set preload="auto": <a-scene> <a-assets> <!-- These will not block. --> <audio src="blockus.mp3"></audio> <video src="loadofblocks.mp4">&...

Content fetched by <a-asset-item> will be returned as plain text. If we want to use a different response type such as arraybuffer, use <a-asset-item>'s response-type attribute: <a-asset-item response-type="arraybuffer" src="model.gltf"></a-asset-item> ...

Every element in A-Frame inherits from <a-node>, the AFRAME.ANode prototype. ANode controls load and initialization order. For an element to initialize (whether it be <a-assets>, <a-asset-item>, <a-scene>, or <a-entity>), its children must have already initialized. N...

A-Frame's animation system can animate different types of properties. vec3 Properties A-Frame has standard vec3 components (i.e., position, rotation, and scale). These components consist of three factors: X, Y, and Z. We can pass three space-delimited numbers to the from and to attributes just a...

Properties of a multi-property component will merge if defined by multiple mixins and/or the entity. For example: <a-scene> <a-assets> <a-mixin id="box" geometry="primitive: box"></a-mixin> <a-mixin id="tall" geometry="heigh...

When an entity includes multiple mixins that define the same component properties, the right-most mixin takes precedence. In the example below, the entity includes both red and blue mixins, and since the blue mixin is included last, the final color of the cube will be blue. <a-scene> &l...