The <needle-engine> web-component comes with a nice collection of built-in attributes that can be used to modify the look and feel of the loaded scene without the need to add or edit the three.js scene directly.
The table below shows a list of the most important ones:

Attribute	Description
Loading
`src`	Path to one or multiple glTF or glb files. Supported types are `string`, `string[]` or a stringified array (`,` separated)
`dracoDecoderPath`	URL to the draco decoder e.g. `./include/draco/` to use the local Draco decoder
`dracoDecoderType`	draco decoder type. Options are `wasm` or `js`. See three.js documentation
`ktx2DecoderPath`	URL to the KTX2 decoder e.g. `./include/ktx2/` to use the local KTX2 decoder
Rendering
`background-color`	optional, hex color to be used as a background color. Examples: `rgb(255, 200, 100)`, `#dddd00`
`background-image`	optional, URL to a skybox image (background image) or a preset string: `studio`, `blurred-skybox`, `quicklook`, `quicklook-ar`
`background-blurriness`	optional, bluriness value between 0 (no blur) and 1 (max blur) for the `background-image`. Example: `background-blurriness="0.5"`
`environment-image`	optional, URL to a environment image (environment light) or a preset string: `studio`, `blurred-skybox`, `quicklook`, `quicklook-ar`
`contactshadows`	optional, render contact shadows
`tone-mapping`	optional, supported values are `none`, `linear`, `neutral`, `agx`
`tone-mapping-exposure`	optional number e.g. increase exposure with `tone-mapping-exposure="1.5"`, requires `tone-mapping` to be set
Interaction
`autoplay`	add or set to `true` to auto play animations e.g. `<needle-engine autoplay`
`camera-controls`	add or set to `true` to automatically add OrbitControls if no camera controls are found in the scene
`auto-rotate`	add to enable auto-rotate (only used with `camera-controls`)
Events
`loadstart`	Name of the function to call when loading starts. Note that the arguments are `(ctx:Context, evt:Event)`. You can call `evt.preventDefault()` to hide the default loading overlay
`progress`	Name of the function to call when loading updates. `onProgress(ctx:Context, evt: {detail: {context:Context, name:string, index:number, count:number, totalProgress01:number}) { ... }`
`loadfinished`	Name of the function to call when loading finishes
Loading Display	Available options to change how the Needle Engine loading display looks. Use `?debugloadingrendering` for easier editing
`loading-background`	PRO — Default: `transparent`. Change the loading background color (e.g. `#dd5500`)
`loading-logo-src`	PRO — Change the loading logo image (e.g. `https://yourdomain.com/logo.png` or `/logo.png`)
`hide-loading-overlay`	PRO — Do not show the loading overlay
Internal
`hash`	Used internally, is appended to the files being loaded to force an update (e.g. when the browser has cached a glb file). Should not be edited manually.

Upgrade notice:

Removed attributes in Needle Engine 4.5.0 loading-style, loading-background-color, loading-text-color, primary-color, secondary-color

Examples

<!-- Setting the path to a custom glb to be loaded -->
<needle-engine src="path/to/your.glb"></needle-engine>

<!-- Overriding where the draco decoder is located -->
<needle-engine src="path/to/your.glb" dracoDecoderPath="./include/draco/"></needle-engine>

Setting environment images, playing animation and automatic camera controls. See it live on stackblitz

<needle-engine
      camera-controls
      auto-rotate
      autoplay
      skybox-image="https://dl.polyhaven.org/file/ph-assets/HDRIs/hdr/1k/industrial_sunset_puresky_1k.hdr"
      environment-image="https://dl.polyhaven.org/file/ph-assets/HDRIs/hdr/1k/industrial_sunset_puresky_1k.hdr"
      src="https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/2.0/DamagedHelmet/glTF-Embedded/DamagedHelmet.gltf"
      >
      </needle-engine>

Receiving an event when the needle-engine context has finished loading:

<needle-engine loadfinished="onLoadFinished"> </needle-engine>
<script>
    function onLoadFinished() {
        console.log("Needle Engine has finished loading");
    }
</script>

Custom Loading Style (PRO)

You can easily modify how Needle Engine looks by setting the appropriate attributes on the <needle-engine> web component. Please see the table above for details.

See code on github