PIXI.js v3 expects canvas to support events

[donpark]

In particular, PIXI.js v3 makes addEventListener calls on canvas element.

Note that this is a partial fix only to get past runtime errors. Firing canvas element events PIXI.js uses will complete the fix.

[drkibitz]

@donpark Is the problem that events are only allowed on document without these changes?

[drkibitz]

Although I like these changes myself, just wanted to note that you can also change the interactive target element here:
https://github.com/GoodBoyDigital/pixi.js/blob/master/src/interaction/InteractionManager.js#L179

Did you try setting the InteractionManager's element to document?

[donpark]

Is the problem that events are only allowed on document without these changes?

Problem was that PIXI.js expects canvas element to have addEventListener method. I didn't bother looking into which events it was dependent on so this is just superficial patch to avoid PIXI.js breaking during initialization.

Did you try setting the InteractionManager's element to document?

No. This was just a probe to see viability of using Ejecta w/PIXI.js so I just took the first solution that worked.

Please do feel free to ignore my PR. It's intended just as a FYI since it's incomplete and, as you pointed out, may not be the optimal solution. :-)