Indeed. If the authors stop by, consider changing the message to something more like

"Your browser does no appear to support a couple things required to play this presentation(WebGL, Web Audio etc). The latest versions of several browsers do. You might want to try one of those instead."

thanks, yes, working on a fix right now. we also want to make it clear that those things are not necessarily required for p5.js itself, just the demo.

but they're obviously required to do things in the demo no?

Safari 7 has WebGL but is disabled by default. Enable developer menus, then click on "Enable WebGL".

> The only modern browsers left out appears to be Safari 7 (no WebGL)

Safari has WebGL since 5-ish but disabled by default.

To enable, Safari > Preferences > Advanced > Show Develop menu, then Develop > Enable WebGL

The presentation seems to work allright, although it suffers from some slowdowns.

I'm aware of that but it effectively doesn't exist for the public if it's gated behind a developer option. This goes double for Safari on iOS.

That said, I was happy to have it run well on my system with WebGL enabled since that should make it a smooth transition when Safari 8 is released.

Works perfectly in Safari 8 running in Yosemite Beta

Yeah, I'm expecting WebGL to be realistic for many sites in the next year. Even Microsoft is moving to automatic updates and Apple would be foolish not to release Safari 8 at least on 10.8/10.9 since the WebKit nightly builds run perfectly there.