API Docs for: 1.0.0

Stage

Extends Component
Module: rendering
Parent Module: xeogl

A Stage is a bin of Entities that is rendered in a specified priority with respect to other Stages in the same Scene.

Overview

  • When the parent Scene renders, each Stage renders its bin of Entities in turn, from the lowest priority Stage to the highest.
  • Stages are typically used for ordering the render-to-texture steps in posteffects pipelines.
  • You can control the render order of the individual Entities within a Stage by associating them with Layers.
  • Layers are typically used to transparency-sort the Entities within Stages.
  • Entities not explicitly attached to a Stage are implicitly attached to the Scene's default stage. which has a priority value of zero.

Examples

Usage

In this example we're performing render-to-texture using ColorTarget and Texture components.

The first Entity renders its fragment colors to a ColorTarget, which is piped into a Texture that's applied to a second Entity. To ensure that the ColorTarget is rendered before the Texture that consumes it, we've attached each Entity to a prioritized Stage.

// First stage: an Entity that renders to a ColorTarget
var entity1 = new xeogl.Entity({
   stage: new xeogl.Stage({
       priority: 0
   }),
   geometry: new xeogl.BoxGeometry(),
   colorTarget: new xeogl.ColorTarget()
});

// Second stage: an Entity with a Texture that sources from the ColorTarget
var entity2 = new xeogl.Entity({
   stage: new xeogl.Stage( {
       priority: 1
   }),
   material: new xeogl.PhongMaterial({
       diffuseMap: new xeogl.Texture({
           target: entity1.colorTarget
       })
   }),
   geometry: new xeogl.BoxGeometry()
});

Constructor

Stage

(
  • [scene]
  • [cfg]
)

Parameters:

  • [scene] Scene optional

    Parent Scene - creates this Stage in the default Scene when omitted.

  • [cfg] optional

    Configs

    • [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 Stage.

    • [priority=0] Number optional

      The rendering priority for the attached Entities.

    • [pickable=true] Boolean optional

      Indicates whether attached Entities are pickable.

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(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 configuration:

var material2 = component.create(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. You can release the shared component instance with a call to Scene/putSharedComponent:method, and once you have released it as many times as you got it, the Scene will destroy the component.

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.

pickable

Boolean

Indicates whether the attached Entities are pickable (see Canvas/pick:method).

Fires a pickable event on change.

Default: true

priority

Number

Indicates the rendering priority for the Entities in this Stage.

Fires a priority event on change.

Default: 0

scene

Scene final

The parent Scene that contains this Component.

string

String final

Inherited from Component but overwritten in src/component.js:1058

String containing the serialized JSON state of 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.

pickable

Fired whenever this Stage's Stage/pickable:pickable property changes.

Event Payload:

  • value Object

    The property's new value

priority

Fired whenever this Stage's priority property changes.

Event Payload:

  • value Object

    The property's new value