NgxThree

NgxThree wraps three.js in Angular components. It allows to render 3d Scenes in a declarative way. And you can leverage the angular features and ecosystem your are familiar with.

What's in the box

ngx-three uses code generation to be able to provide as much functionality from three js. This approach makes it possible to follow three.js updates with minimal effort.

ngx-three:

• generates wrappers (> 130) for three.js class categories:
  • Object3d,
  • Material,
  • Geometry,
  • Post processing passes,
  • Controls
  • Textures
• Adds support for simple pointer event handling
• Easy handling of async model loading
• Supports Multi-View / Multi-Scene scenarios
• enables declarative post processing
• ...

The project is inspired by the great react three fiber library. But in contrast to RTF angular components are generated that wrap three.js classes.

Check out some examples

Performance

From a performance perspective it's important to know, that ngx-three components do not produce any DOM elements.

In addition the generate classes use OnPush change detection strategy and the scene rendering runs outside the angular zone.

This means there is no overhead because of additional DOM elements and the impact of angular's change detection mechanism should be minimized.

Installation

npm install ngx-three

In addition to ngx-three you have to install it's peer dependencies Angular (setup howto), three.js and its typings

npm install three
npm install @types/three

You can use npm to get the exact peer dependency versions for ngx-three

npm info ngx-three peerDependencies

Introductory Example

We are going to create a basic example showing a cube, with animation and interaction.

Step 1) Basic Angular Component

Lets start by creating a simple component with an empty template.

import { Component } from '@angular/core';

@Component({
  selector: 'app-example',
  template: `  `,
})
export class ExampleComponent {}

Step 2) Add a Canvas

As a second step we start filling the template with a canvas and a scene (the most basic setup).

Step 3) Adding a Mesh ( The Box )

In this step we are adding a mesh with material and geometry. You can add material and geometry to the mesh by nesting th-*Material and th-*Geometry components inside a th-mesh componet.

By means of the args attribute you can pass parameters to the constructor of the three.js basic material.

Step 4) Camera and Light

Now lets bring some (ambient)light to the scene.

The perspective camera takes multiple constructor arguments.
These can be passed to the camera constructor by passing an an array holding the arguments to args.

The position of the camera is set by means of the position attribute.

Step 5) Interacting with the box

By adding a boolean member selected to our class we can modify the scale of the cube

  (onClick)="selected = !selected" [scale]="selected ? [2, 2, 2] : [1, 1, 1]"
  ...

Step 6) Animating the box

By reacting to the canvas' onRender we can animate the box by setting its rotation.

Template:

  ...
   ... 
  ...

Component:

  ...
  public rotation: [x: number, y: number, z: number] = [0, 0, 0];
  public onBeforeRender() {
    this.rotation = [0, this.rotation[2] + 0.01, this.rotation[2] + 0.01];
  }
  ...

Step 7) Creating a reusable Angular component

The mesh part of the current code can be seperated into its own class Then we can use two instances ot the box component in the app component Take a look at the working example

Box Template:

Box Component:

@Component({
  selector: 'app-box',
  template: `...`,
  changeDetection: ChangeDetectionStrategy.OnPush,
})
export class Box {
  selected = false;
  @Input()
  public rotation: [x: number, y: number, z: number] = [0, 0, 0];
  @Input()
  public position: [x: number, y: number, z: number] = [0, 0, 0];
}

App Template:

App Component:

@Component({
  selector: 'app-example',
  template: `...`
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class ExampleComponent {
  public rotation: [x: number, y: number, z: number] = [0, 0, 0];
  public onBeforeRender() {
    this.rotation = [0, this.rotation[2] + 0.01, this.rotation[2] + 0.01];
  }
}

Canvas / View / Scene / Renderers

Canvas View and Scene are the main building blocks of ngx-three.

ThCanvas

In general the ThCanvas contains ThView istances, and a ThView contains a ThScene.

In a standard scenario ThCanvas provides (or actually 'is') the default view. So a typical template might look like this

   ... 

ThCanvas creates the canvas dom element that's used for rendering. Actually ThCanvas is the only ngx-three component that inserts an element into dom!

ThCanvas provides the ThEngineService. That means if you have multiple ThCanvas instances every one gets its own engine service.

As ThCanvas is derived from ThView it also shares its inputs / outputs

In addition ThCanvas also provides an input rendererParameters. It takes a configuration object that allows for setting all the members provided by the THREE.WebGLRenderer.

ThView

One can say that ThView provides the view port. The view consists of:

• a scene ThScene
• a camera (ThCamera)
• and an optional effect composer (ThEffectComposer)

This combination makes it possible to render multiple scenarios

• The same scene with multiple camera perspectives (Multi View Example)
• mutliple scenes with the same camera (Multi Scene Example)
• one / multiple scene with multiple effects (Multi Effects Example)

ThScene

ThScene is the ngx-three wrapper of THREE.Scene and provides all of its members as inputs. It is mandatory for rendering.

Renderers

ngx-thre supports different renderers provided by three.js:

• WebGLRenderer
• CSS3DRenderer
• CSS2DRenderer

And they can be combined too!

You can configure them in two different ways

• by providing them with the helper functions provideWebGLRenderer, provideCSS2dRenderer and provideCSS3dRenderer:

    @Component({
    selector: 'app-example',
    providers: [provideCSS3dRenderer({...})],
    ...
  })
  

  or provideWebGLRenderer({...}) or provideCSS2dRenderer({...})

• or by means of structural directives:

  
  ... 
  
  

  or *css2dRendererParameters]="{...}", *css3dRendererParameters]="{...}"

If you do not provide any renderer the WebGLRenderer is used as the default renderer with its default configuration.

Examples:

• CSS3DRenderer Example
• Multi Renderer Example
• Html with CSS3D Renderer Example

ThAnimationLoop / ThEngineService / ThRenderDirective

Render Loop

The ThAnimationLoop service runs the render loop. You can start and stop the loop. In addition you can request a 'one-shotrendering by calling the Service-methodrequestAnimationFrame`;

You can react to a 'global' render event by means of listening to the ThAnimationLoop.beforeRender$ observable or by using the beforeRender output of the ThRenderDirective.

In addition you can react to the onRender outputs of the ThView (ThCanvas is derived from it) instances.

Resize-Handling & Device Pixel Ratio

For common scenarios ngx-three handles resizing automatically by observing the size of the canvas.

But for special scenarios (Multi View Example) you might have to do calculations when the size changes. This can be achieved by:

• using the onResize event of the ThRenderDirective.

• or by subscribing to the resize$ of the ThEngineService

The ThEngineService takes care of resizing, does the rendering and organizes the available views (ThView)

> Note: The engine service automatically takes into account the device pixel ratio when calculating the renderer dimensions. This works dynamically i.e.: when moving the window from one display to a second one with different device pixel ratio.

On-Demand Rendering

In case you do not need an animation (i.e.: static model viewer) you can disable the animation loop by setting renderOnDemand to true. From this time on the render calls only happen in following cases:

• Angular change detection is triggered for one of ThCanvas' children
• A controller fires an event

This works with OrbitControls, MapControls, DragControls, TransformControls and ArcBallControls. But FlyControls, TrackbalControls and FirstPersonControls need a render loop. You can play with these controls and on-demand rendering in the On-Demand Example.

Example:

This allows to render only once to show a scene (i.e.: resulting from a loaded GLB file). And while you move the camera by means of the orbit control continuous render calls will be triggered. When you stop moving no render calls will happen.

Let's say you change the background color that is bound in a template. In this case the angular changed detection mechanism triggers and the scene is rendered (once).

Objects / Meshes

In three.js anything that can be added to a Scene is an Object3D. In ngx-three the component ThObject3D with the tag th-object3D can be seen as the equivalent.

A mesh (Three.Mesh) can be represented by th-mesh in ngx-three. A mesh can have a material (ThMaterial) and a Geometry(ThGeometry).

Every ngx-three object has a member called objRef this one holds the reference to the three.js object. For example ThMesh has a member objRef: THREE.Mesh.

Referencing objects in a component

There are two ways to reference existing ngx-three object class instances.

1) ViewChild

You can use ViewChild to reference template objects from within the component code.

@Component({
  selector: 'app-myapp',
  template: `  `,
})
export class MyApp {
  @ViewChild(ThMesh, { static: true }) mesh: ThMesh;
}

2) Angular Template Variables

Referencing ngx-three objects (th-object3D) can be easiliy referenced from within the template by means of template variables

How to put existing THREE.Object3D objects into the angular template

If you want to put an existing object into the angular component tree (maybe it was easier to construct the specific object in an imperative way) this can be easily achieved by setting the objRef Attribute

Model Loading

ngx-three provides an easy way to load models / scenes and apply it to a th-object3D element. It implements a generic loader service, loader directive and loader pipe, That is then used by the specific loader implementations

All types of loaders can load models by means of:

• a loader service
  • provides a Promise of the resulting 'model'
  • a progress callback
• a directive
  • applies the model to the host ThObject3d component ( to its objRef)
  • provides a progress output
  • provides a loaded output
• a pipe
  • provides a progress callback

under the hood the directive and the pipe use the service One example is the GLTF-Loader

GLTF Loader

Loading GLTF / GLB files can be achieved by using the loadGLTF directive:

the loadGLTF pipe:

or by using the GLTFLoaderService directly:

...
constructor(private service: GLTFLoaderService) {
}

async ngOnInit() {
  const result: GLTF = await service.load('assets/helmet.glb');
}

the load method of the service uses the three.js Loader.loadAsync method under the hood and also provides the same parameters

load(url: string, onProgress?: (event: ProgressEvent) => void): Promise;

You can find an example here

DRACO Compression

To load draco compressed gltf files you have to specify the path to a folder containing the WASM/JS decoding libraries. All you have to do is to inject the DRACOLoaderService and set the decoder path.

constructor(dracoLoader: DRACOLoaderService) {
    // specify the draco decoder path used by the gltf loader instances
    dracoLoader.setDecoderPath('https://raw.githubusercontent.com/mrdoob/three.js/dev/examples/jsm/libs/draco/gltf/');
}

You may have to specify a different crossOrigin string to implement CORS i.e.:

dracoLoader.setCrossOrigin('no-cors'); // just for testing (default: "anonymous")

By default, a single DRACOLoader is reused when loading consecutive models. To change this behaviour, explicitly disable it:

dracoLoader.setReuseInstance(false); // (default: true)

You can find an example here

Creating your own Loader

In addition to the pre-defined loaders it is actually quite simple to add additional loader Service / Directive / Pipe.

The below example shows how to implement simple 'obj' loading

Creating the service is as simple as deriving from ThAsyncLoaderService and setting the clazz member to the Loader class provided by three.js.

@Injectable({
  providedIn: 'root',
})
export class OBJLoaderService extends ThAsyncLoaderService {
  public readonly clazz = OBJLoader;
}

Creating your own loader pipe is equaly simple. You just have to derive from ThAsyncLoaderBasePipe and inject the previously defined service.

@Pipe({
  name: 'loadObj',
  pure: true,
})
export class ThObjLoaderPipe
  extends ThAsyncLoaderBasePipe
  implements PipeTransform
{
  constructor(protected service: OBJLoaderService) {
    super();
  }
}

The directive can be implemented as follows:

@Directive({
  selector: '[loadObj]',
})
export class ThObjLoaderDirective extends ThAsyncLoaderBaseDirective {
  constructor(
    @Host() protected host: ThObject3D,
    protected zone: NgZone,
    protected service: OBJLoaderService
  ) {
    super(host, zone);
  }

  protected getRefFromResponse(response: Group) {
    return response;
  }
}

• you have to inject the previously implemented service
• and implement the method getRefFromResponse. The value returned by this method is applied to the host ThObject3D's objRef member.

FBXLoader

The FBXLoader can be used like the GLTF loader by using the loadFBX directive:

the loadFBX pipe:

or by using the FBXLoaderService directly.

PLYLoader

The PLYLoader is a little bit different than the previous Loaders (i.e.: GLTFLoader). Because the PLYLoader only provides/loads geometry and no material. In contrast the GLTFLoader loads a full scene.

You can use the PLYLoader directive:

or the pipe

or you can use the PLYLoader service directly.

You can find an example here

Caching Models

to enable loader caching you can use three.js' built in cache:

THREE.Cache.enabled = true;

Texture Loading

ngx-three generates wrappers for

• CanvasTexture
• CompressedTexture
• CubeTexture
• DataTexture
• DataTexture2DArray
• DataTexture3D
• DepthTexture
• Texture
• VideoTexture
• FramebufferTexture

all those wrappers can be placed in an angular template

and you can reuse it in the template by means of a template reference (i.e.: myTexture);

To load a Texture you have 3 possibilities (service, pipe, directive)

• place a loader directive on a wrapper component

• use the loader pipe

• use the injected service

  ...
  constructor(service: TextureLoaderService) {
    const texture = service.load('thetexture.jpg')
  }
  

  the loaders provide event emitters / callbacks for 'loaded' and 'progress'

  Following texture loaders are available:

  • TextureLoaderService, ThTextureLoaderDirective, ThTextureLoaderPipe
  • CubeTextureLoaderService, ThCubeTextureLoaderDirective, ThCubeTextureLoaderPipe,
  • Data Texture Loaders
    • ThDDSLoaderDirective, ThDDSLoaderPipe, DDSLoaderService
    • ThKTXLoaderDirective, ThKTXLoaderPipe, KTXLoaderService
    • ThKTX2LoaderDirective, ThKTX2LoaderPipe, ThKTX2LoaderService
    • ThPVRLoaderDirective, ThPVRLoaderPipe, PVRLoaderService
  • Compressed Texture Loaders
    • ThEXRLoaderDirective, ThEXRLoaderPipe, EXRLoaderService
    • ThRGBELoaderDirective, ThRGBELoaderPipe, RGBELoaderService
    • ThRGBMLoaderDirective, ThRGBMLoaderPipe, RGBMLoaderService
    • ThTGALoaderDirective, ThTGALoaderPipe, TGALoaderService

  the pipe and directive names follow a naming scheme load*Texture where * can be '', Cube, DDS, EXR ...

Event Handling

Mouse / Pointer Events

ngx-three supports the following mouse/pointer events:

• onClick
• onMouseEnter
• onMouseExit
• onPointerDown
• onPointerUp

All of them return a RaycasterEmitEvent that holds the target component and the intersection data of raycaster.intersectObject (except for onMouseExit)

Object 3D Events

Every th-object3D element emits property changes. you can listen to it like this:

Utilitiy Pipes / Directives

ngx-three provides some utility pipes that ease input assignments

ThRenderDirective

This directive can be used to react to 'global' rendering loop events.

Listen to the beforeRender output to to apply changes before the next rendering run happens.

If you want to do something directly after the rendering pass use afterRender.

color pipe

Use this pipe to create a Color from any of it's constructor parameters

  ...

vector pipes

the vector2, vector3, and vector4 construct the respective vector from an array of numbers usage:

clone pipe

calls clone on a clonable three.js instance (or it's ngx-three wrapper) and ensures that the clone call only happens once

bind pipe

binds a function to an object by means of Function.prototype.bind()

plane pipe

creates a three.js plane instance from an array of numbers [x,y,z] ( = normal vector ) and an optional argument ( = constant: the signed distance from the origin to the plane ).

ref-by-id directive

A utility directive that helps you selecting a specific node of a model.

You can find an example here

Stats Directive

If you want to display the well known stats panel you can do that simply by adding the thStats directive to the canvas.

 ... 

Debugging

With ngx-three you can leverage the full potential of Angular DevTools without sacrificing performance.

In dev-mode (ng serve) ngx-three can be debugged with the DevTools: by inserting the Angular components into the dom:

And in production mode / build not a single additional dom node is inserted for the wrapped three.js objects:

IF you create your own components intended to be rendered inside of the three.js node tree don't forget to insert a `` inside of your template. Then you can see child nodes attached to your component in debug mode!