Pin
A Pin is a pinned position on the surface of a Mesh.
Overview
Position
A Pin is positioned within one of the triangles of its Mesh'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:
- localPos - 3D position local to the coordinate space of the Geometry,
- worldPos - 3D World-space position,
- viewPos - 3D View-space position, and
- canvasPos - 2D Canvas-space position.
An Pin automatically recalculates these coordinates whenever its Mesh 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 Mesh with a TorusGeometry, then attach a Pin to it. Then we'll subscribe to changes to the Pin's position and visibility status.
var mesh = new xeogl.Mesh({
geometry: new xeogl.TorusGeometry(),
transform: new xeogl.Translate({
xyz: [0,0,0]
});
});
var pin = new xeogl.Pin({
mesh: mesh,
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 Mesh 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 -
[cfg]optionalConfigs
-
[id]String optionalOptional ID, unique among all components in the parent Scene, generated automatically when omitted.
-
[meta]String:Object optionalOptional map of user-defined metadata to attach to this Pin.
-
[mesh]Number | String | Mesh optionalID or instance of the Mesh the Pin is attached to.
-
[primIndex=0]Number optionalIndex of the triangle containing the Pin. Within the Mesh's Geometry indices, this is the index of the first vertex for the triangle.
-
[bary=[0.3,0.3,0.3]Float32Array optionalBarycentric coordinates of the Pin within its triangle.
-
[offset=0.2]Number optionalHow 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=false]Boolean optionalIndicates 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.
-
Index
Properties
Methods
create
-
[cfg]
Convenience method for creating a Component within this Component's Scene.
The method is given a component configuration, like so:
var material = myComponent.create({
type: "xeogl.PhongMaterial",
diffuse: [1,0,0],
specular: [1,1,0]
}, "myMaterial");Parameters:
-
[cfg]optionalConfiguration for the component instance.
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:
-
messageStringThe 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:
-
eventStringThe event type name
-
valueObjectThe event parameters
-
[forget=false]Boolean optionalWhen true, does not retain for subsequent subscribers
hasSubs
-
event
Returns true if there are any subscribers to the given event on this component.
Parameters:
-
eventStringThe event
Returns:
True if there are any subscribers to the given event on this component.
isType
-
type
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 Component/superTypes:property, 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.Mesh); // Returns false, because xeogl.Rotate does not (even indirectly) extend xeogl.MeshParameters:
-
typeString | FunctionComponent type to compare with, eg "xeogl.PhongMaterial", or a xeogl component constructor.
Returns:
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>
Parameters:
-
messageStringThe message to log
off
-
subId
Cancels an event subscription that was previously made with Component#on() or Component#once().
Parameters:
-
subIdStringPublication subId
on
-
event -
callback -
[scope=this]
Subscribes to an event on this component.
The callback is be called with this component as scope.
Parameters:
-
eventStringThe event
-
callbackFunctionCalled fired on the event
-
[scope=this]Object optionalScope for the callback
Returns:
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 subIdd.
This is equivalent to calling Component#on(), and then calling Component#off() inside the callback function.
Parameters:
-
eventStringData event to listen to
-
callbackFunction(data)Called when fresh data is available at the event
-
[scope=this]Object optionalScope for the callback
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
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]
mesh
Number | String | xeogl.Mesh
model
Model
final
The Model which contains this Component, if any.
Will be null if this Component is not in a Model.
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: false
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 Mesh, this is the index of the first element for that triangle.
Fires a primIndex event on change.
Default: 0
type
String
final
JavaScript class name for this Component.
For example: "xeogl.AmbientLight", "xeogl.MetallicMaterial" etc.
viewPos
Float32Array
final
View-space 3D coordinates of this Pin.
This is read-only and is automatically calculated.
Default: [0,0,0]
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
worldNormal
Float32Array
final
World-space normal vector of this Pin.
This is read-only and is automatically calculated.
Fires a worldNormal event on change.
Default: [0,0,1]
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:
-
valueObjectFloat32Array The property's new value
destroyed
Fired when this Component is destroyed.
localPos
Fired whenever this Pin's localPos property changes.
mesh
Fired whenever this Pin's mesh property changes.
Event Payload:
-
valueObjectThe property's new value
occludable
Fired whenever this Pin's occludable property changes.
Event Payload:
-
valueObjectFloat32Array The property's new value
offset
Fired whenever this Pin's offset property changes.
Event Payload:
-
valueObjectNumber The property's new value
primIndex
Fired whenever this Pin's primIndex property changes.
Event Payload:
-
valueObjectNumber The property's new value
visible
Fired whenever this Pin's visible property changes.
Event Payload:
-
valueObjectFloat32Array The property's new value
worldNormal
Fired whenever this Pin's worldNormal property changes.
worldPos
Fired whenever this Pin's worldPos property changes.