API Docs for: 1.0.0

Component

Defined in: src/component.js:1
Module: xeogl

The Component class is the base class for all xeogl components.

Component IDs

Every Component has an ID that's unique within the parent Scene. xeogl generates the IDs automatically by default, however you can also specify them yourself. In the example below, we're creating a scene comprised of Scene, Material, Geometry and Entity components, while letting xeogl generate its own ID for the Geometry:

// The Scene is a Component too
var scene = new xeogl.Scene({
   id: "myScene"
});

var material = new xeogl.PhongMaterial(scene, {
   id: "myMaterial"
});

var geometry = new xeogl.Geometry(scene, {
   id: "myGeometry"
});

// Let xeogl automatically generate the ID for our Entity
var entity = new xeogl.Entity(scene, {
   material: material,
   geometry: geometry
});

We can then find those components like this:

// Find the Scene
var theScene = xeogl.scenes["myScene"];

// Find the Material
var theMaterial = theScene.components["myMaterial"];

Properties

Almost every property on a xeogl Component fires a change event when you update it. For example, we can subscribe to the diffuse event that a Material fires when its diffuse property is updated, like so:

// Bind a change callback to a property
var handle = material.on("diffuse", function(diffuse) {
   console.log("Material diffuse color has changed to: [" + diffuse[0] + ", " + diffuse[1] + "," + diffuse[2] + "]");
});

// Change the property value, which fires the callback
material.diffuse = [ 0.0, 0.5, 0.5 ];

// Unsubscribe from the property change event
material.off(handle);

We can also subscribe to changes in the way components are attached to each other, since components are properties of other components. For example, we can subscribe to the 'material' event that a Entity fires when its material property is set to a different Material:

// Bind a change callback to the Entity's Material
entity1.on("material", function(material) {
   console.log("Entity's Material has changed to: " + material.id);
});

// Now replace that Material with another
entity1.material = new xeogl.PhongMaterial({
   id: "myOtherMaterial",
   diffuse: [ 0.3, 0.3, 0.6 ]
   //..
});

Metadata

You can set optional metadata on your Components, which can be anything you like. These are intended to help manage your components within your application code or content pipeline. You could use metadata to attach authoring or version information, like this:

// Scene with authoring metadata
var scene = new xeogl.Scene({
   id: "myScene",
   meta: {
       title: "My awesome 3D scene",
       author: "@xeolabs",
       date: "February 13 2015"
   }
});

// Material with descriptive metadata
var material = new xeogl.PhongMaterial(scene, {
   id: "myMaterial",
   diffuse: [1, 0, 0],
   meta: {
       description: "Bright red color with no textures",
       version: "0.1",
       foo: "bar"
   }
});

As with all properties, you can subscribe and change the metadata like this:

// Subscribe to changes to the Material's metadata
material.on("meta", function(value) {
   console.log("Metadata changed: " + JSON.stringify(value));
});

// Change the Material's metadata, firing our change handler
material.meta = {
   description: "Bright red color with no textures",
   version: "0.2",
   foo: "baz"
};

Logging

Components have methods to log ID-prefixed messages to the JavaScript console:

material.log("Everything is fine, situation normal.");
material.warn("Wait, whats that red light?");
material.error("Aw, snap!");

The logged messages will look like this in the console:

[LOG]   myMaterial: Everything is fine, situation normal.
[WARN]  myMaterial: Wait, whats that red light..
[ERROR] myMaterial: Aw, snap!

Destruction

Get notification of destruction directly on the Components:

material.on("destroyed", function() {
   this.log("Component was destroyed: " + this.id);
});

Or get notification of destruction of any Component within its Scene, indiscriminately:

scene.on("componentDestroyed", function(component) {
   this.log("Component was destroyed: " + component.id);
});

Then destroy a component like this:

material.destroy();

Other Components that are linked to it will fall back on a default of some sort. For example, any Entities that were linked to our Material will then automatically link to the Scene's default material.

Constructor

Component

(
  • [scene]
  • [cfg]
)

Defined in src/component.js:1

Parameters:

  • [scene] Scene optional

    Parent Scene - creates this Component within the default Scene when omitted.

  • [cfg] optional

    DepthBuf configuration

    • [id] String optional

      Optional ID, unique among all components in the parent Scene, generated automatically when omitted.

    • [meta] String:Object optional

      Optional map of user-defined metadata to attach to this Component.

    • [isDefault] Boolean optional

      Set true when this is one of xeogl's default components.

Methods

create

(
  • [cfg]
  • [instanceId]
)

Convenience method for creating a Component within this Component's Scene.

You would typically use this method to conveniently instantiate components that you'd want to share (ie. "instance") among your Entities.

The method is given a component type, configuration and optional instance ID, like so:

var material = myComponent.create({
     type: "xeogl.PhongMaterial",
     diffuse: [1,0,0],
     specular: [1,1,0]
}, "myMaterial");

The first time you call this method for the given type and instanceId, this method will create the PhongMaterial, passing the given attributes to the component's constructor.

If you call this method again, specifying the same type and instanceId, the method will return the same component instance that it returned the first time, and will ignore the new configuration:

var material2 = component.create({ type: "xeogl.PhongMaterial", specular: [1,1,0] }, "myMaterial");

So in this example, our PhongMaterial will continue to have the red specular and diffuse color that we specified the first time.

Each time you call this method with the same type and instanceId, the Scene will internally increment a reference count for the component instance.

Parameters:

  • [cfg] optional

    Configuration for the component instance - only used if this is the first time you are getting the component, ignored when reusing an existing instance.

  • [instanceId] String | Number optional

    Identifies the shared component instance. Note that this is not used as the ID of the component - you can specify the component ID in the cfg parameter.

Returns:

:

destroy

()

Destroys this component.

Fires a destroyed event on this Component.

Automatically disassociates this component from other components, causing them to fall back on any defaults that this component overrode on them.

TODO: describe effect with respect to #create

error

(
  • message
)

Logs an error for this component to the JavaScript console.

The console message will have this format: [ERROR] [<component type> =<component id>: <message>

Also fires the message as an error event on the parent Scene.

Parameters:

  • message String

    The message to log

fire

(
  • event
  • value
  • [forget=false]
)

Fires an event on this component.

Notifies existing subscribers to the event, optionally retains the event to give to any subsequent notifications on the event as they are made.

Parameters:

  • event String

    The event type name

  • value Object

    The event parameters

  • [forget=false] Boolean optional

    When true, does not retain for subsequent subscribers

isType

(
  • type
)
Boolean

Tests if this component is of the given type, or is a subclass of the given type.

The type may be given as either a string or a component constructor.

This method works by walking up the inheritance type chain, which this component provides in property superTypes, returning true as soon as one of the type strings in the chain matches the given type, of false if none match.

Examples:

var myRotate = new xeogl.Rotate({ ... });

myRotate.isType(xeogl.Component); // Returns true for all xeogl components
myRotate.isType("xeogl.Component"); // Returns true for all xeogl components
myRotate.isType(xeogl.Rotate); // Returns true
myRotate.isType(xeogl.Transform); // Returns true
myRotate.isType("xeogl.Transform"); // Returns true
myRotate.isType(xeogl.Entity); // Returns false, because xeogl.Rotate does not (even indirectly) extend xeogl.Entity

Parameters:

  • type String | Function

    Component type to compare with, eg "xeogl.PhongMaterial", or a xeogl component constructor.

Returns:

Boolean:

True if this component is of given type or is subclass of the given type.

log

(
  • message
)

Logs a console debugging message for this component.

The console message will have this format: [LOG] [<component type> <component id>: <message>

Also fires the message as a log event on the parent Scene.

Parameters:

  • message String

    The message to log

off

(
  • handle
)

Cancels an event subscription that was previously made with on or once.

Parameters:

  • handle String

    Publication handle

on

(
  • event
  • callback
  • [scope=this]
)
String

Subscribes to an event on this component.

The callback is be called with this component as scope.

Parameters:

  • event String

    The event

  • callback Function

    Called fired on the event

  • [scope=this] Object optional

    Scope for the callback

Returns:

String:

Handle to the subscription, which may be used to unsubscribe with {@link #off}.

once

(
  • event
  • callback
  • [scope=this]
)

Subscribes to the next occurrence of the given event, then un-subscribes as soon as the event is handled.

This is equivalent to calling on, and then calling off inside the callback function.

Parameters:

  • event String

    Data event to listen to

  • callback Function(data)

    Called when fresh data is available at the event

  • [scope=this] Object optional

    Scope for the callback

warn

(
  • message
)

Logs a warning for this component to the JavaScript console.

The console message will have this format: [WARN] [<component type> =<component id>: <message>

Also fires the message as a warn event on the parent Scene.

Parameters:

  • message String

    The message to log

Properties

destroyed

Boolean

True as soon as this Component has been destroyed

id

String final

Unique ID for this Component within its parent Scene.

isDefault

Boolean

Indicates whether this is one of the Scene's built-in Components.

json

JSON final

JSON object containing the state of this Component.

metadata

Object

Arbitrary, user-defined metadata on this component.

scene

Scene final

The parent Scene that contains this Component.

string

String final

String containing the serialized JSON state of this Component.

string

String final

Experimental: string containing a JavaScript expression that would instantiate this Component.

superTypes

Array of String final

An array of strings that indicates the chain of super-types within this component's inheritance hierarchy.

For example, if this component is a Rotate, which extends Transform, which in turn extends Component, then this property will have the value:

["xeogl.Component", "xeogl.Transform"]
                    

Note that the chain is ordered downwards in the hierarchy, ie. from super-class down towards sub-class.

type

String final

JavaScript class name for this Component.

This is used when loading Scenes from JSON, and is included in the JSON representation of this Component, so that this class may be instantiated when loading it from the JSON representation.

For example: "xeogl.AmbientLight", "xeogl.ColorTarget", "xeogl.Lights" etc.

Events

destroyed

Fired when this Component is destroyed.