## Rapidly Build Interactive 3D Apps for the Web
Threlte is a [Svelte](https://svelte.dev/) library that simplifies creating 3D apps for the web. It provides a **declarative**, **type-safe**, **reactive** and **interactive** API out-of-the-box.
Threlte's **3D rendering** is powered by [Three.js](https://threejs.org/), and it also provides a **physics engine** through [Rapier](https://rapier.rs/) and an **animation studio** via [Theatre.js](https://www.theatrejs.com/); see [packages](#packages) for details.
Check out our **[documentation](https://threlte.xyz)** and our **[Discord community](https://discord.gg/EqUBCfCaGm)**.
## @threlte/gltf
[@threlte/gltf](https://threlte.xyz/docs/reference/gltf/getting-started) gives you a CLI to that turn GLTF assets into declarative and reusable Threlte components.
This helps with performance optimization for asset-heavy Threlte apps. It also allows you to modify your GLTF assets as Svelte components, instead of working with 3D software like Blender.
### Motivation
#### The GLTF workflow on the web is not ideal ...
- GLTF is thrown wholesale into the scene which prevents re-use, in threejs objects can only be mounted once
- Contents can only be found by traversal which is cumbersome and slow
- Changes to queried nodes are made by mutation, which alters the source data and prevents re-use
- Re-structuring content, making nodes conditional or adding/removing is cumbersome
- Model compression is complex and not easily achieved
- Models often have unnecessary nodes that cause extra work and matrix updates
#### @threlte/gltf fixes that
- 🧑💻 It creates a virtual graph of all objects and materials. Now you can easily alter contents and re-use.
- 🏎️ The graph gets pruned (empty groups, unnecessary transforms, ...) and will perform better.
- ⚡️ It will optionally compress your model with up to 70%-90% size reduction.
## Usage
```bash
Usage
$ npx @threlte/gltf@latest [Model.glb] [options]
Options
--output, -o Output file name/path
--types, -t Add Typescript definitions
--keepnames, -k Keep original names
--keepgroups, -K Keep (empty) groups, disable pruning
--meta, -m Include metadata (as userData)
--shadows, -s Let meshes cast and receive shadows
--printwidth, -w Prettier printWidth (default: 120)
--precision, -p Number of fractional digits (default: 2)
--draco, -d Draco binary path
--preload -P Add preload method to module script
--suspense -u Make the component suspense-ready
--isolated, -i Output as isolated module (No $$restProps usage)
--root, -r Sets directory from which .gltf file is served
--transform, -T Transform the asset for the web (draco, prune, resize)
--resolution, -R Transform resolution for texture resizing (default: 1024)
--simplify, -S Transform simplification (default: false) (experimental!)
--weld Weld tolerance (default: 0.0001)
--ratio Simplifier ratio (default: 0.75)
--error Simplifier error threshold (default: 0.001)
--debug, -D Debug output
```
### Requirements
- NodeJS must be installed
- The GLTF file has to be present in your projects `/public` folder
- [three](https://github.com/mrdoob/three.js/) (>= 122.x)
- @threlte/core > 5.0.0
- @threlte/core > 4.9.3
### Support
Have questions? Feel free to ask in our [Discord support forum](https://discord.com/channels/985983540804091964/1031843197963477002).
### A typical use-case
First you run your model through `@threlte/gltf`. `npx` allows you to use npm packages without installing them.
```bash
npx @threlte/gltf@latest model.gltf --transform
```
This will create a `Model.svelte` file that plots out all of the assets contents.
```svelte
{#if $gltf}
{/if}
```
Add your model to your `/public` folder as you would normally do. With the `--transform` flag it has created a compressed copy of it (in the above case `model-transformed.glb`). Without the flag just copy the original model.
```text
/public
model-transformed.glb
```
The component can now be dropped into your scene.
```svelte
```
You can re-use it, it will re-use geometries and materials out of the box:
```svelte
```
Or make the model dynamic. Change its colors for example:
```svelte
```
Or exchange materials:
```svelte
```
Make contents conditional:
```svelte
{#if condition}
}
{/if}
```
## Features
#### ⚡️ Draco and meshopt compression ootb
You don't need to do anything if your models are draco compressed, since `useGltf` defaults to a [draco CDN](https://www.gstatic.com/draco/v1/decoders/). By adding the `--draco` flag you can refer to [local binaries](https://github.com/mrdoob/three.js/tree/dev/examples/js/libs/draco/gltf) which must reside in your /public folder.
#### ⚡️ Auto-transform (compression, resize)
With the `--transform` flag it creates a binary-packed, draco-compressed, texture-resized (1024x1024), webp compressed, deduped, instanced and pruned \*.glb ready to be consumed on a web site. It uses [glTF-Transform](https://github.com/donmccurdy/glTF-Transform). This can reduce the size of an asset by 70%-90%.
It will not alter the original but create a copy and append `[modelname]-transformed.glb`.
#### ⚡️ Type-safety
Add the `--types` flag and your component will be typesafe.
```svelte
{#if $gltf}
{/if}
```
#### ⚡️ Easier access to animations
If your GLTF contains animations it will add [@threlte/extras's `useGltfAnimations`](https://threlte.xyz/extras/use-gltf-animations) hook, which extracts all clips and prepares them as actions:
```ts
const gltf = useGltf('/stacy.glb')
export const {(actions, mixer)} = useGltfAnimations(gltf, ref)
```
If you want to play an animation you can do so at any time:
```ts
const onEvent = () => {
$actions.jump.play()
}
```
## Using the parser stand-alone
```jsx
import { parse } from '@threlte/gltf'
import { GLTFLoader, DRACOLoader } from 'three-stdlib'
const gltfLoader = new GLTFLoader()
const dracoloader = new DRACOLoader()
dracoloader.setDecoderPath('https://www.gstatic.com/draco/v1/decoders/')
gltfLoader.setDRACOLoader(dracoloader)
gltfLoader.load(url, (gltf) => {
const component = parse(filename, gltf, config)
})
```
## Contributing
Contributions are what make the open source community such an amazing place to learn, inspire, and create. Any contributions you make are **greatly appreciated**.
- **Filing Issues** - if you have feature requestions or you think you spotted a bug, [submit an issue](https://github.com/threlte/threlte/issues/new).
- **Contributing Code** - if you would like to drop us a PR, read the [contribution guide](https://github.com/threlte/threlte/blob/main/CONTRIBUTING.md) first.
## Sponsors
[](https://vercel.com/?utm_source=threlte&utm_campaign=oss)
---
### License
The MIT License (MIT). Please see the [License File](LICENSE.md) for more information.
