This loop
Try this.
Shape
Palette
Playback
Keys: ← / → report what you see, space pauses,
f fades the help.
The twins
as shown
mirrored in depth, turning the other way
Two different objects, two different rotations, drawn
independently — and at help 0 these two canvases are identical, pixel for pixel,
forever. That is the whole illusion, and it is an exact algebraic fact rather than a good
approximation. Push the help up and watch them come apart: it is the depth information the
flat picture never had.
Your numbers