Hah, so my comment here spawned a post: https://news.ycombinator.com/item?id=45904434

ok, i dont get it.

on my phone at typical distance and 90 scale i only see about an asprin tablet size area spinning. but at 180 scale i see almost everything spinning at same distance.

i think peripheral vision is quite sensitive to movement/contrast changes, but the moving shapes have to be large enough to trigger those receptors?

not sure what to conclude from this.

Does anyone know how the hell this works

Hi, I don't know what this is supposed to do, but I get pretty bad migraines and loading the page made me feel extremely strange almost immediately so I closed it.

I would check to make sure this can't trigger migraines or seizures. Maybe it's just me, but also, please double check.

I don't get it, all I see is:

"Bad request"

am I missing the joke?

This is a truly incredible demo.

What’s the correct scale for 210dpi?

TL;DR it helps you identify the true diameter of your visual focus, which is said to shrink with old age (mine shrinks more in terms of _time_ dimension but that's a different issue!)

For best results, use it _fullscreen_, change the #define `90` values to a higher value if you're on a high dpi screen.

Stare at a few places on the screen and you'll get the effect of appearing to rotate only where you stare.

It's pretty neat.

Amazing - but iPhone screen is too small. Works on my iPad.