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offscreen-canvas

(★ 342)

Polyfill for OffscreenCanvas to move Three.js/WebGL/2D canvas to Web Worker

파일 탐색기

최종 버전 다운로드 (.zip)

- .browserslistrc
- index.html
- index.js
- worker.js
.editorconfig
.gitignore
.npmignore
.travis.yml
CHANGELOG.md
create-worker.js
inside-worker.js
LICENSE
package.json
README.md
yarn.lock

# 설치 가이드

1. 코드 내려받기

git clone https://github.com/ai/offscreen-canvas

깃허브에서 프로젝트 코드 전체를 내 컴퓨터로 내려받습니다.

cd offscreen-canvas

방금 내려받은 프로젝트 폴더 안으로 이동합니다.

2. Node.js

쉬움 추천

사전 준비물

Git GitHub에서 프로젝트 코드를 내려받으려면 필요합니다.
Node.js npm 명령어를 쓰려면 Node.js가 설치되어 있어야 합니다. LTS(장기지원) 버전을 추천합니다.

npm install

package.json에 명시된 라이브러리들을 내려받아 설치합니다.

npm start

개발/실행 서버를 켭니다.

✅ 명령어 실행 후 터미널에 나타나는 주소(보통 http://localhost:3000 형태)를 브라우저에서 열어보세요.

// repository documentation

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# Offscreen Canvas Polyfill

JS polyfill (**375 bytes**) for `OffscreenCanvas` to move **Three.js**,
**WebGL** or 2D canvas to **Web Worker**.

It will improve performance in Chrome and will load worker by `<script>`
in Firefox, Safari, and other browsers.

The tutorial for this library:
**[Faster WebGL/Three.js 3D graphics with OffscreenCanvas and Web Workers]**.

```js
// index.js
import createWorker from 'offscreen-canvas/create-worker'

const worker = createWorker(canvas, '/worker.js', e => {
  // Messages from the worker
})

button.addEventListener('click', () => {
  worker.post({ message: 'update' })
})
```

```js
// worker.js
import insideWorker from 'offscreen-canvas/inside-worker'

const worker = insideWorker(e => {
  if (e.data.canvas) {
    // Draw on the canvas
  } else if (e.data.message === 'move') {
    // Messages from main thread
  }
})
```

[Faster WebGL/Three.js 3D graphics with OffscreenCanvas and Web Workers]: https://dev.to/evilmartians/faster-webgl-three-js-3d-graphics-with-offscreencanvas-and-web-workers-43he

<a href="https://evilmartians.com/?utm_source=offscreen-canvas">
  <img src="https://evilmartians.com/badges/sponsored-by-evil-martians.svg"
       alt="Sponsored by Evil Martians" width="236" height="54">
</a>

## Usage

Create separated bundle in webpack, Parcel or any other bundler:

```diff js
  entry: {
    app: './src/app.js',
+   worker: './src/worker.js'
  }
```

Move all code working with `<canvas>` to `worker.js`. It means to move all WebGL
or Three.js imports and scene related code.

```js
import insideWorker from 'offscreen-canvas/inside-worker'
// Move Three.js imports here if you use Three.js

const worker = insideWorker(e => {
  if (e.data.canvas) {
    // Move scene building code here
  }
})
```

Some of Three.js code (mostly loaders) will not work in Web Worker.
Use `worker.isWorker` to switch loaders:

```js
    if (worker.isWorker) {
      loader = new ImageBitmapLoader()
    } else {
      loader = new ImageLoader()
    }
```

Put preload link to HTML templates with a URL to `worker.js`.
Your bundle will add cache buster to bundle names, so bundle names will
change every time you deploy application. This is why we need to store
path to `worker.js` in HTML:

```diff html
+   <link rel="preload" as="script" href="./worker.js">
  </head>
```

Load worker in main `app.js`:

```js
import createWorker from 'offscreen-canvas/create-worker'

const workerUrl = document.querySelector('[rel=preload][as=script]').href
const canvas = document.querySelector('canvas')

const worker = createWorker(canvas, workerUrl)
```

Keep all UI interaction code (listeners for clicks, mouse move, etc)
in `app.js`. Send message to Worker when your need to update `<canvas>`
after user actions:

```js
button.addEventListener('click', () => {
  worker.post({ message: 'move' })
})
```

Process this messages in the worker:

```diff js
  const worker = insideWorker(e => {
    if (e.data.canvas) {
      // Move scene building code here
-   }
+   } else if (e.data.message === 'move') {
+     // Move object on the scene
+   }
  })
```