API Docs for: 1.0.0

Frustum

Extends Transform
Module: transforms
Parent Module: xeogl

A Frustum is a Transform that defines a perspective projection as a frustum-shaped view volume.

Overview

  • Camera components pair these with viewing transform components, such as Lookat, to define viewpoints for attached Entities.
  • A Frustum lets us explicitly set the positions of the left, right, top, bottom, near and far planes, which is useful for asymmetrical view volumes, such as those used for stereo viewing.
  • An Frustum's near and far properties specify the distances to the WebGL clipping planes.
  • Use Ortho if you just want to specify the X,Y frustum extents with a single scale factor, ie. without individually specifying the distance to each frustum plane.
  • Use Perspective if you need perspective projection.

Examples

Usage

new xeogl.Entity({

    camera: xeogl.Camera({

       view: new xeogl.Lookat({
           eye: [0, 0, -4],
           look: [0, 0, 0],
           up: [0, 1, 0]
       }),

       project: new xeogl.Frustum(scene, {
           left: -0.1,
           right: 0.1,
           bottom: -0.1,
           top: 0.1,
           near: 0.15,
           far: 1000
       })
    }),

    geometry: new xeogl.BoxGeometry()
});

Constructor

Frustum

(
  • [scene]
  • [cfg]
)

Parameters:

  • [scene] Scene optional

    Parent Scene, creates this Frustum within 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 Frustum.

    • [left=-1] Number optional

      Position of the Frustum's left plane on the View-space X-axis.

    • [right=1] Number optional

      Position of the Frustum's right plane on the View-space X-axis.

    • [bottom=-1] Number optional

      Position of the Frustum's bottom plane on the View-space Y-axis.

    • [top=1] Number optional

      Position of the Frustum's top plane on the View-space Y-axis.

    • [near=0.1] Number optional

      Position of the Frustum's near plane on the View-space Z-axis.

    • [far=1000] Number optional

      Position of the Frustum's far plane on the positive View-space Z-axis.

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

bottom

Number

Position of this Frustum's bottom plane on the View-space Y-axis.

Fires a bottom event on change.

Default: -1.0

destroyed

Boolean

True as soon as this Component has been destroyed

far

Number

Position of this Frustum's far plane on the positive View-space Z-axis.

Fires a far event on change.

Default: 10000.0

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.

left

Number

Position of this Frustum's left plane on the View-space X-axis.

Fires a left event on change.

Default: -1.0

matrix

Float32Array

Inherited from Transform but overwritten in src/transforms/transform.js:371

The Transform's local matrix.

Fires a matrix event on change.

Default: [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]

metadata

Object

Arbitrary, user-defined metadata on this component.

near

Number

Position of this Frustum's near plane on the positive View-space Z-axis.

Fires a near event on change.

Default: 0.1

parent

Transform

The parent Transform.

Fires a parent event on change.

postMultiply

Boolean

Flag that indicates whether this Transform is post-multiplied (default) or pre-multiplied by its parent Transform.

Fires an postMultiply event on change.

Default: true

right

Number

Position of this Frustum's right plane on the View-space X-axis.

Fires a right event on change.

Default: 1.0

scene

Scene final

The parent Scene that contains this Component.

string

String final

Inherited from Component but overwritten in src/component.js:1056

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.

top

Number

Position of this Frustum's top plane on the View-space Y-axis.

Fires a top event on change.

Default: 1.0

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

bottom

Fired whenever this Frustum's bottom property changes.

Event Payload:

  • value Object

    The property's new value

destroyed

Fired when this Component is destroyed.

far

Fired whenever this Frustum's far property changes.

Event Payload:

  • value Object

    The property's new value

left

Fired whenever this Frustum's left property changes.

Event Payload:

  • value Object

    The property's new value

matrix

Fired whenever this Transform's matrix property changes.

Event Payload:

  • value Object

    The property's new value

near

Fired whenever this Frustum's near property changes.

Event Payload:

  • value Object

    The property's new value

parent

Fired whenever this Transform's parent property changes.

Event Payload:

  • value Object

    The property's new value

postMultiply

Fired whenever this Transform's postMultiply property changes.

Event Payload:

  • value Object

    The property's new value

right

Fired whenever this Frustum's right property changes.

Event Payload:

  • value Object

    The property's new value

top

Fired whenever this Frustum's top property changes.

Event Payload:

  • value Object

    The property's new value

updated

Fired whenever this Transform's Transform/leafMatrix:property property changes.

This event does not carry the updated property value. Instead, subscribers will need to read that property again to get its updated value (which may be lazy-computed then).