API Docs for: 1.0.0

Pin

Extends Component
Module: annotations
Parent Module: xeogl

A Pin is a pinned position on the surface of an Entity.

Overview

Position

An Pin is positioned within one of the triangles of its Entity's Geometry. Wherever that triangles goes within the 3D view, the Pin will automatically follow. An Pin specifies its position with two properties:

  • primIndex, which indicates the index of the triangle within the Geometry indices, and
  • bary, the barycentric coordinates of the position within the triangle.

From these, an Pin dynamically calculates its Cartesian coordinates, which it provides in each xeogl coordinate space:

An Pin automatically recalculates these coordinates whenever its Entity is replaced or transformed, the Geometry is replaced or modified, or the Camera is moved.

Visibility

  • occludable specifies whether the Pin becomes invisible whenever its occluded by other objects in the 3D view, and
  • visible indicates if the Pins is currently visible.

  • To determine if each Pin is occluded, xeogl renders the scene to a hidden framebuffer, along with a colored point for each Pin's position. Then xeogl determines each Pin to be occluded if the pixel at its position does not match the special pin color. The color is configured as some unusual color that is not used elsewhere in the scene.

Example

In the example below we'll create an Entity with a TorusGeometry, then attach a Pin to it. Then we'll subscribe to changes to the Pin's position and visibility status.

var entity = new xeogl.Entity({
   geometry: new xeogl.TorusGeometry(),
   transform: new xeogl.Translate({
       xyz: [0,0,0]
   });
});

var pin = new xeogl.Pin({
   entity: entity,
   primIndex: 12,              // Triangle index in Geometry indices array
   bary: [0.11, 0.79, 0.08]    // Barycentric coordinates in the triangle
});

var localPos   = pin.localPos;     // 3D Local-space position
var worldPos   = pin.worldPos;     // 3D World-space position
var viewPos    = pin.viewPos;      // 3D View-space position
var canvasPos  = pin.canvasPos;    // 2D Canvas-space position

// Listen for change of the Pin's Local-space cartesian position,
// which is caused by modification of Pin's Geometry or update to
// the Pin's 'primIndex' or 'bary' properties.
pin.on("localPos", function() {
   //...
});

// Listen for change of the Pin's World-space cartesian position,
// which is caused by update of Pin's Local-space position or by
// animation of the Entity by its modelling Transform.
pin.on("worldPos", function() {
   //...
});

// Listen for change of Pin visibility. The Pin becomes invisible when it
// falls outside the canvas, or when an object occludes the Pin's position
// in the 3D view.
pin.on("visible", function(visible) { // Pin visibility has changed
   if (visible) {
       this.log("Pin is not occluded and within canvas.");
   } else {
       this.log("Pin is either occluded or is off the canvas.");
   }
});

Constructor

Pin

(
  • [scene]
  • [cfg]
)

Parameters:

  • [scene] Scene optional

    Parent Scene - creates this Pin 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 Pin.

    • [entity] Number | String | Entity optional

      ID or instance of the Entity the Pin is attached to.

    • [primIndex=0] Number optional

      Index of the triangle containing the Pin. Within the Entity's Geometry indices, this is the index of the first vertex for the triangle.

    • [bary=[0.3,0.3,0.3]] Float32Array optional

      Barycentric coordinates of the Pin within its triangle.

    • [offset=0.2] Number optional

      How far the Pin is lifted out of its triangle, along the surface normal vector. This is used when occlusion culling, to ensure that the Pin is not lost inside the surface it's attached to.

    • [occludable=true] Boolean optional

      Indicates whether occlusion testing is performed for the Pin, where it will be flagged invisible whenever it's hidden by something else in the 3D view.

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

bary

Float32Array

Barycentric coordinates of this Pin within its triangle.

A value of [0.3, 0.3, 0.3] is the center of the triangle.

Fires a bary event on change.

Default: [0.3,0.3,0.3]

canvasPos

Float32Array final

Canvas-space 2D coordinates of this Pin.

This is read-only and is automatically calculated.

Default: [0,0]

destroyed

Boolean

True as soon as this Component has been destroyed

entity

Number | String | xeogl.Entity

The Entity this Pin is attached to.

You can attach a Pin to a different Entity at any time.

Note that primIndex should always be within the indices of the Geometry belonging to the Entity.

Fires an entity event on change.

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.

localPos

Float32Array final

Local-space 3D coordinates of this Pin.

This is read-only and is automatically calculated.

Fires a localPos event on change.

Default: [0,0,0]

metadata

Object

Arbitrary, user-defined metadata on this component.

occludable

Float32Array

Indicates whether occlusion testing is performed for this Pin.

When this is true, then visible will be false whenever the Pin is hidden behind something else in the 3D view.

Set this false if the Pin is to remain visible when hidden behind things while being within the canvas.

Fires a occludable event on change.

Default: true

offset

Number

How far the Pin is lifted out of its triangle, along the surface normal vector.

This is used when occlusion culling, to ensure that the Pin is not lost inside the surface it's attached to.

Fires a offset event on change.

Default: 0.2

primIndex

Number

Index of the triangle containing this pin.

Within the indices of the Geometry attached to the Entity, this is the index of the first element for that triangle.

Fires a primIndex 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:1055

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.

viewPos

Float32Array final

View-space 3D coordinates of this Pin.

This is read-only and is automatically calculated.

Default: [0,0]

visible

Boolean final

Indicates if this Pin is currently visible.

This is read-only and is automatically calculated.

The Pin is invisible whenever:

  • canvasPos is currently outside the canvas, or
  • occludable is true and the Pin is currently occluded by something in the 3D view.

Fires a visible event on change.

Default: true

worldPos

Float32Array final

World-space 3D coordinates of this Pin.

This is read-only and is automatically calculated.

Fires a worldPos event on change.

Default: [0,0,0]

Events

bary

Fired whenever this Pin's bary property changes.

Event Payload:

  • value Object

    Float32Array The property's new value

destroyed

Fired when this Component is destroyed.

entity

Fired whenever this Pin's entity property changes.

Event Payload:

  • value Object

    The property's new value

localPos

Fired whenever this Pin's localPos property changes.

occludable

Fired whenever this Pin's occludable property changes.

Event Payload:

  • value Object

    Float32Array The property's new value

offset

Fired whenever this Pin's offset property changes.

Event Payload:

  • value Object

    Number The property's new value

primIndex

Fired whenever this Pin's primIndex property changes.

Event Payload:

  • value Object

    Number The property's new value

visible

Fired whenever this Pin's visible property changes.

Event Payload:

  • value Object

    Float32Array The property's new value

worldPos

Fired whenever this Pin's worldPos property changes.