(question) how to composite multiple children using blendFunc

### question

#### library version
3.6.0

```bash
npm ls gl-react gl-react-dom gl-react-native gl-react-expo
gl-react@3.6.0
└── gl-react-dom@3.6.0
```

This should be a relatively simple question, but I'm not seeing an easy way to composite multiple nodes together while being able to take advantage of the parent node's blendFunc.

The only way I can currently see of implementing this is to re-implement the blendFunc in the parent node's shader and have the multiple children passed in as textures, but this seems really backwards, so I'm guessing I'm missing something. None of the examples really use `blendFunc` or composite multiple children together.

Here's a [jsfiddle](http://jsfiddle.net/76o6mhj5/) with a DOM example of what I'm trying to accomplish.

Also, I absolutely love using `gl-react` -- keep up the great work!! :)