Phenakistoscope

The phenakistoscope is a nineteenth century optical toy, its a spinning disc printed with sequential frames, viewed through a mirror with slots that strobe the image into apparent motion. I rebuilt it in TouchDesigner to understand the mechanism.

The illusion depends entirely on the relationship between frame count, rotational speed, and the persistence of vision threshold. Get any one of those wrong and the motion breaks down, you either see blur or you see individual frames.

Implementing it meant working with rotation, timing, and compositing in ways that felt more like engineering than design. The constraint of the format forced a precision that looser tools don't require, and that precision was the point.