API Docs for: 0.7.0

Geometry

Extends Component
Module: geometry
Parent Module: xeogl

A Geometry defines a mesh for attached Entities.

Usage

Geometry compression

Geometries are automatically quantized to reduce memory and GPU bus usage. Usually, geometry attributes such as positions and normals are stored as 32-bit floating-point numbers. Quantization compresses those attributes to 16-bit integers represented on a scale between the minimum and maximum values. Decompression is then done on the GPU, via a simple matrix multiplication in the vertex shader.

Disabling

Since each normal vector is oct-encoded into two 8-bit unsigned integers, this can cause them to lose precision, which may affect the accuracy of any operations that rely on them being perfectly perpendicular to their surfaces. In such cases, you may need to disable compression for your geometries and models:

// Disable geometry compression when loading a Model
var model = new xeogl.GLTFModel({
   src: "models/gltf/modern_office/scene.gltf",
   quantizeGeometry: false // Default is true
});

// Disable compression when creating a Geometry
var entity = new xeogl.Entity({
   geometry: new xeogl.TeapotGeometry({
       quantized: false // Default is true
   }),
   material: new xeogl.PhongMaterial({
       diffuse: [0.2, 0.2, 1.0]
   })
});

Geometry batching

Geometries are automatically combined into the same vertex buffer objects (VBOs) so that we reduce the number of VBO binds done by WebGL on each frame. VBO binds are expensive, so this really makes a difference when we have large numbers of Entities that share similar Materials (as is often the case in CAD rendering).

Disabling

Since combined VBOs need to be rebuilt whenever we destroy a Geometry, we can disable this optimization for individual Models and Geometries when we know that we'll be continually creating and destroying them.

// Disable VBO combination for a GLTFModel
var model = new xeogl.GLTFModel({
   src: "models/gltf/modern_office/scene.gltf",
   combinedGeometry: false // Default is true
});

// Disable VBO combination for an individual Geometry
var entity = new xeogl.Entity({
   geometry: new xeogl.TeapotGeometry({
       combined: false // Default is true
   }),
   material: new xeogl.PhongMaterial({
       diffuse: [0.2, 0.2, 1.0]
   })
});

Constructor

Geometry

(
  • [scene]
  • [cfg]
)

Parameters:

  • [scene] Scene optional

    Parent Scene - creates this Geometry 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 Geometry.

    • [primitive="triangles"] String optional

      The primitive type. Accepted values are 'points', 'lines', 'line-loop', 'line-strip', 'triangles', 'triangle-strip' and 'triangle-fan'.

    • [positions] Array of Number optional

      Positions array.

    • [normals] Array of Number optional

      Vertex normal vectors array.

    • [uv] Array of Number optional

      UVs array.

    • [colors] Array of Number optional

      Vertex colors.

    • [indices] Array of Number optional

      Indices array.

    • [autoNormals=false] Boolean optional

      Set true to automatically generate normal vectors from the positions and indices, if those are supplied.

    • [quantized=true] Boolean optional

      Stores positions, colors, normals and UVs in quantized and oct-encoded formats for reduced memory footprint and GPU bus usage.

    • [combined=false] Boolean optional

      Combines positions, colors, normals and UVs into the same WebGL vertex buffers with other Geometries, in order to reduce the number of buffer binds performed per frame.

    • [ghostEdgeThreshold=2] Number optional

      When a Entity renders this Geometry as wireframe, this indicates the threshold angle (in degrees) between the face normals of adjacent triangles below which the edge is discarded.

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] optional

    Configuration 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:

  • 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

hasSubs

(
  • event
)
Boolean

Returns true if there are any subscribers to the given event on this component.

Parameters:

  • event String

    The event

Returns:

Boolean:

True if there are any subscribers to the given event on this component.

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

aabb

Float32Array final

Local-space axis-aligned 3D boundary (AABB) of this geometry.

The AABB is represented by a six-element Float32Array containing the min/max extents of the axis-aligned volume, ie. [xmin, ymin,zmin,xmax,ymax, zmax].

colors

Float32Array

The Geometry's vertex colors.

Default: null

combined

Boolean final

Indicates if this Geometry is combined.

Combination is an internally-performed optimization which combines positions, colors, normals and UVs into the same WebGL vertex buffers with other Geometries, in order to reduce the number of buffer binds performed per frame.

Default: false

destroyed

Boolean

True as soon as this Component has been destroyed

id

String final

Unique ID for this Component within its parent Scene.

indices

Uint16Array | Uint32Array final

The Geometry's indices.

If xeogl.WEBGL_INFO.SUPPORTED_EXTENSIONS["OES_element_index_uint"] is true, then this can be a Uint32Array, otherwise it needs to be a Uint16Array.

Default: null

isDefault

Boolean

Indicates whether this is one of the Scene's built-in Components.

metadata

Object

Arbitrary, user-defined metadata on this component.

normals

Float32Array

The Geometry's vertex normals.

Default: null

obb

Float32Array final

Local-space oriented 3D boundary (OBB) of this geometry.

The OBB is represented by a 32-element Float32Array containing the eight vertices of the box, where each vertex is a homogeneous coordinate having [x,y,z,w] elements.

positions

Float32Array

The Geometry's vertex positions.

Default: null

primitive

String

The Geometry's primitive type.

Valid types are: 'points', 'lines', 'line-loop', 'line-strip', 'triangles', 'triangle-strip' and 'triangle-fan'.

Default: "triangles"

quantized

Boolean final

Indicates if this Geometry is quantized.

Compression is an internally-performed optimization which stores positions, colors, normals and UVs in quantized and oct-encoded formats for reduced memory footprint and GPU bus usage.

Quantized geometry may not be updated.

Default: false

scene

Scene final

The parent Scene that contains 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.

For example: "xeogl.AmbientLight", "xeogl.ColorTarget", "xeogl.Lights" etc.

uv

Float32Array

The Geometry's UV coordinates.

Default: null

Events

boundary

Fired whenever this Geometry's boundary changes.

Get the latest boundary from the Geometry's aabb and obb properties.

destroyed

Fired when this Component is destroyed.