[page:Object3D] → [page:Line] → [page:LineSegments] →

# [name]

Visualizes an object's vertex normals. Requires that normals have been specified in a [page:BufferAttribute custom attribute] or have been calculated using [page:BufferGeometry.computeVertexNormals computeVertexNormals].

## Import

[name] is an add-on, and must be imported explicitly. See [link:#manual/introduction/Installation Installation / Addons].

`import { VertexNormalsHelper } from 'three/addons/helpers/VertexNormalsHelper.js';`

## Code Example

`const geometry = new THREE.BoxGeometry( 10, 10, 10, 2, 2, 2 ); const material = new THREE.MeshStandardMaterial(); const mesh = new THREE.Mesh( geometry, material ); const helper = new VertexNormalsHelper( mesh, 1, 0xff0000 ); scene.add( mesh ); scene.add( helper );`

## Examples

[example:webgl_helpers WebGL / helpers]

## Constructor

### [name]( [param:Object3D object], [param:Number size], [param:Hex color] )

[page:Object3D object] -- object for which to render vertex normals.
[page:Number size] -- (optional) length of the arrows. Default is *1*.
[page:Hex color] -- (optional) hex color of the arrows. Default is *0xff0000*.

## Properties

See the base [page:LineSegments] class for common properties.

### [property:Object matrixAutoUpdate]

See [page:Object3D.matrixAutoUpdate]. Set to `false` here as the helper is using the object's [page:Object3D.matrixWorld matrixWorld].

### [property:Object3D object]

The object for which the vertex normals are being visualized.

### [property:Number size]

Length of the arrows. Default is *1*.

## Methods

See the base [page:LineSegments] class for common methods.

### [method:undefined update]()

Updates the vertex tangents preview based on the object's world transform.

### [method:undefined dispose]()

Frees the GPU-related resources allocated by this instance. Call this method whenever this instance is no longer used in your app.

## Source

[link:https://github.com/mrdoob/three.js/blob/master/examples/jsm/helpers/VertexNormalsHelper.js examples/jsm/helpers/VertexNormalsHelper.js]