Class: LabelCollection

LabelCollection

new LabelCollection(optionsopt)

A renderable collection of labels. Labels are viewport-aligned text positioned in the 3D scene. Each label can have a different font, color, scale, etc.


Example labels


Labels are added and removed from the collection using LabelCollection#add and LabelCollection#remove.
Parameters:
Name Type Attributes Description
options Object <optional>
 Object with the following properties:
Properties
Name Type Attributes Default Description
modelMatrix Matrix4 <optional>
 Matrix4.IDENTITY The 4x4 transformation matrix that transforms each label from model to world coordinates.
debugShowBoundingVolume Boolean <optional>
 false For debugging only. Determines if this primitive's commands' bounding spheres are shown.
scene Scene <optional>
 Must be passed in for labels that use the height reference property or will be depth tested against the globe.
Source:
See:
Example
// Create a label collection with two labels
var labels = scene.primitives.add(new Cesium.LabelCollection());
labels.add({
  position : new Cesium.Cartesian3(1.0, 2.0, 3.0),
  text : 'A label'
});
labels.add({
  position : new Cesium.Cartesian3(4.0, 5.0, 6.0),
  text : 'Another label'
});

Members

debugShowBoundingVolume :Boolean

This property is for debugging only; it is not for production use nor is it optimized.

Draws the bounding sphere for each draw command in the primitive.

Type:
  • Boolean
Default Value:
  • false
Source:

length :Number

Returns the number of labels in this collection. This is commonly used with LabelCollection#get to iterate over all the labels in the collection.
Type:
  • Number
Source:

modelMatrix :Matrix4

The 4x4 transformation matrix that transforms each label in this collection from model to world coordinates. When this is the identity matrix, the labels are drawn in world coordinates, i.e., Earth's WGS84 coordinates. Local reference frames can be used by providing a different transformation matrix, like that returned by Transforms.eastNorthUpToFixedFrame.
Type:
Default Value:
Source:
Example
var center = Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883);
labels.modelMatrix = Cesium.Transforms.eastNorthUpToFixedFrame(center);
labels.add({
  position : new Cesium.Cartesian3(0.0, 0.0, 0.0),
  text     : 'Center'
});
labels.add({
  position : new Cesium.Cartesian3(1000000.0, 0.0, 0.0),
  text     : 'East'
});
labels.add({
  position : new Cesium.Cartesian3(0.0, 1000000.0, 0.0),
  text     : 'North'
});
labels.add({
  position : new Cesium.Cartesian3(0.0, 0.0, 1000000.0),
  text     : 'Up'
});

Methods

add(optionsopt) → {Label}

Creates and adds a label with the specified initial properties to the collection. The added label is returned so it can be modified or removed from the collection later.
Parameters:
Name Type Attributes Description
options Object <optional>
 A template describing the label's properties as shown in Example 1.
Source:
See:
Throws:
This object was destroyed, i.e., destroy() was called.
Type
DeveloperError
Returns:
The label that was added to the collection.
Type
Label
Examples
// Example 1:  Add a label, specifying all the default values.
var l = labels.add({
  show : true,
  position : Cesium.Cartesian3.ZERO,
  text : '',
  font : '30px sans-serif',
  fillColor : Cesium.Color.WHITE,
  outlineColor : Cesium.Color.BLACK,
  style : Cesium.LabelStyle.FILL,
  pixelOffset : Cesium.Cartesian2.ZERO,
  eyeOffset : Cesium.Cartesian3.ZERO,
  horizontalOrigin : Cesium.HorizontalOrigin.LEFT,
  verticalOrigin : Cesium.VerticalOrigin.BOTTOM,
  scale : 1.0
});
// Example 2:  Specify only the label's cartographic position,
// text, and font.
var l = labels.add({
  position : Cesium.Cartesian3.fromRadians(longitude, latitude, height),
  text : 'Hello World',
  font : '24px Helvetica',
});

contains(label) → {Boolean}

Check whether this collection contains a given label.
Parameters:
Name Type Description
label Label The label to check for.
Source:
See:
Returns:
true if this collection contains the label, false otherwise.
Type
Boolean

destroy() → {undefined}

Destroys the WebGL resources held by this object. Destroying an object allows for deterministic release of WebGL resources, instead of relying on the garbage collector to destroy this object.

Once an object is destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception. Therefore, assign the return value (undefined) to the object as done in the example.
Source:
See:
Throws:
This object was destroyed, i.e., destroy() was called.
Type
DeveloperError
Returns:
Type
undefined
Example
labels = labels && labels.destroy();

get(index) → {Label}

Returns the label in the collection at the specified index. Indices are zero-based and increase as labels are added. Removing a label shifts all labels after it to the left, changing their indices. This function is commonly used with LabelCollection#length to iterate over all the labels in the collection.
Parameters:
Name Type Description
index Number The zero-based index of the billboard.
Source:
See:
Throws:
This object was destroyed, i.e., destroy() was called.
Type
DeveloperError
Returns:
The label at the specified index.
Type
Label
Example
// Toggle the show property of every label in the collection
var len = labels.length;
for (var i = 0; i < len; ++i) {
  var l = billboards.get(i);
  l.show = !l.show;
}

isDestroyed() → {Boolean}

Returns true if this object was destroyed; otherwise, false.

If this object was destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception.
Source:
See:
Returns:
True if this object was destroyed; otherwise, false.
Type
Boolean

remove(label) → {Boolean}

Removes a label from the collection. Once removed, a label is no longer usable.
Parameters:
Name Type Description
label Label The label to remove.
Source:
See:
Throws:
This object was destroyed, i.e., destroy() was called.
Type
DeveloperError
Returns:
true if the label was removed; false if the label was not found in the collection.
Type
Boolean
Example
var l = labels.add(...);
labels.remove(l);  // Returns true

removeAll()

Removes all labels from the collection.
Source:
See:
Throws:
This object was destroyed, i.e., destroy() was called.
Type
DeveloperError
Example
labels.add(...);
labels.add(...);
labels.removeAll();