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

Usage

• Component IDs
• Metadata
• Logging
• Destruction
• Creating custom 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 Mesh 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 Mesh
var mesh = new xeogl.Mesh(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"];

// Find all PhongMaterials in the Scene
var phongMaterials = theScene.types["xeogl.PhongMaterial"];

// Find our Material within the PhongMaterials
var theMaterial = phongMaterials["myMaterial"];

Component inheritance

TODO

All xeogl components are (at least indirect) subclasses of the Component base type.

For most components, you can get the name of its class via its type property:

var type = theMaterial.type; // "xeogl.PhongMaterial"

You can also test if a component implements or extends a given component class, like so:

// Evaluates true:
var isComponent = theMaterial.isType("xeogl.Component");

// Evaluates true:
var isMaterial = theMaterial.isType("xeogl.Material");

// Evaluates true:
var isPhongMaterial = theMaterial.isType("xeogl.PhongMaterial");

// Evaluates false:
var isMetallicMaterial = theMaterial.isType("xeogl.MetallicMaterial");

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

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 bodacious 3D scene",
       author: "@xeographics",
       date: "February 30 2018"
   }
});

// 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"
   }
});

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();

Creating custom Components

Subclassing a Component to create a new xeogl.ColoredTorus type:

class ColoredTorus extends xeogl.Component{

    get type() {
       return "ColoredTorus";
    }

    constructor(scene=null, cfg) { // Constructor

        super(scene. cfg);

        this._torus = new xeogl.Mesh({
            geometry: new xeogl.TorusGeometry({radius: 2, tube: .6}),
            material: new xeogl.MetallicMaterial({
                baseColor: [1.0, 0.5, 0.5],
                roughness: 0.4,
                metallic: 0.1
            })
        });

        this.color = cfg.color;
    },

    set color(color) {
        this._torus.material.baseColor = color;
    }

    get color() {
        return this._torus.material.baseColor;
    }

    destroy() {
        super.destroy();
        this._torus.geometry.destroy();
        this._torus.material.destroy();
        this._torus.destroy();
    }
};

Examples

• Custom component definition
• Custom component that fires events
• Custom component that manages child components
• Custom component that schedules asynch tasks