# VelocityVectorProperty

#### new Cesium.VelocityVectorProperty(position, normalize)
engine/Source/DataSources/VelocityVectorProperty.js 29

A `Property` which evaluates to a `Cartesian3` vector based on the velocity of the provided `PositionProperty`.

Name | Type | Default | Description
--- | --- | --- | ---
`position` | PositionProperty |  | optional The position property used to compute the velocity.
`normalize` | boolean | `true` | optional Whether to normalize the computed velocity vector.

##### Example:

    //Create an entity with a billboard rotated to match its velocity.
    const position = new Cesium.SampledProperty();
    position.addSamples(...);
    const entity = viewer.entities.add({
      position : position,
      billboard : {
        image : 'image.png',
        alignedAxis : new Cesium.VelocityVectorProperty(position, true) // alignedAxis must be a unit vector
      }
    }));

### Members

#### readonly definitionChanged : Event
engine/Source/DataSources/VelocityVectorProperty.js 58

Gets the event that is raised whenever the definition of this property changes.

#### readonly isConstant : boolean
engine/Source/DataSources/VelocityVectorProperty.js 46

Gets a value indicating if this property is constant.

#### normalize : boolean
engine/Source/DataSources/VelocityVectorProperty.js 102

Gets or sets whether the vector produced by this property will be normalized or not.

#### position : Property|undefined
engine/Source/DataSources/VelocityVectorProperty.js 69

Gets or sets the position property used to compute the velocity vector.

### Methods

#### equals(other) → boolean
engine/Source/DataSources/VelocityVectorProperty.js 206

Compares this property to the provided property and returns `true` if they are equal, `false` otherwise.

Name | Type | Description
--- | --- | ---
`other` | Property | optional The other property.

##### Returns:

`true` if left and right are equal, `false` otherwise.

#### getValue(time, result) → Cartesian3
engine/Source/DataSources/VelocityVectorProperty.js 130

Gets the value of the property at the provided time.

Name | Type | Default | Description
--- | --- | --- | ---
`time` | JulianDate | `JulianDate.now()` | optional The time for which to retrieve the value. If omitted, the current system time is used.
`result` | Cartesian3 |  | optional The object to store the value into, if omitted, a new instance is created and returned.

##### Returns:

The modified result parameter or a new instance if the result parameter was not supplied.

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