maroslaw/rainyday.js — pull request #28 by iirelu (2013-09-25 08:05:49+00:00)
Title: Made demo pages automatically resize the canvas when the window size changes

I exposed the engine variable in `demo()` on each of the pages and added a function along with an event listener to call `engine.prepareBackground()` upon a resize event.

```javascript
function resize() {
engine.prepareBackground(20, window.innerWidth, window.innerHeight);
}
```