Moire
Rings, lines, grids, rays, spirals and dots drift across each other and weave rippling interference patterns.
Two families of repeating patterns glide slowly across one another, and where they overlap something appears that neither of them contains, rippling bands of interference that bloom and dissolve as the centers drift. It is one of the oldest optical tricks there is, and it never stops being strange to watch.
The buttons pick from ten flavors. Concentric rings in op art black and white, neon colors or a triple weave. Line rasters with broad sweeping fringes. Twisting grids and nested squares that tile the screen with diamond super patterns. Twin sunbursts with beating spokes. Two counter rotating spirals with a hypnotic double heart. Halftone dot screens that bloom into printing press rosettes. And wavy rasters that shimmer like watered silk.
Press and hold anywhere to grab one of the pattern centers and drag the interference around with your hand. Let go and it drifts gently back to its own orbit.