feat: expose expoGL object props

[jeremybarbet]

Hi hi,

I wanted to take a snapshot of my 3D scene in react-native, but the recommended method for the web does not work with expo-gl.

I added a new object expoGL (that could be extended for additional props from the GLView) and passed it a ref props.

Here is a demo of the use case

import { Canvas } from '@react-three/fiber/native';

const Demo = () => {
  const ref = React.useRef<GLView | null>(null)

  const snapshot = React.useCallback(async () => {
    const res = await ref.current?.takeSnapshotAsync()

    if (res?.localUri) {
      // Do something with the image, e.g. upload to R2
    }
  }, [])

  // Call snapshot() to take a snapshot of the canvas

  return <Canvas expoGL={{ ref }} {...} />
}

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[CodyJasonBennett]

I'd prefer to keep this an implementation detail if possible. We can, however, merge the HTML Canvas shim and the actual GLView reference without much trouble. For your purposes though, GLView has a static takeSnapshotAsync method which accepts the current GL context.

[CodyJasonBennett]

Closing as stale. Happy to reopen and resolve conflicts if still current, I believe we can already address use-cases where you'd want the underlying expo-gl handle.