Two near-frequency spatial oscillators beating against each other produce moire shimmer interference

An oscillator-texture (spatial sine stripes) produces periodic stripes and is the basis of striped, op-art, and plasma looks. When two spatial oscillators of slightly different frequencies are combined (added or multiplied), their peaks and troughs reinforce and cancel across the frame, producing large-scale interference patterns — moire shimmer that moves as the frequencies drift. Rotating two oscillators to different angles and combining them produces weave or plaid patterns. These effects are cheap (two sine evaluations) and produce high apparent complexity. Animating the frequency difference over time makes the moire slowly shift, adding visual rhythm without additional elements.

Examples

Hydra: osc(20,0.01).add(osc(21,0.01).rotate(0.1)) — two near-frequency oscs at a slight angle produce a shifting moire. osc(20).rotate(Math.PI/4).add(osc(20).rotate(-Math.PI/4)) = plaid.

Assessment

Describe the moire effect: what causes it in oscillator-texture terms, what does it look like, and how does adjusting the frequency difference between two oscillators change the spatial scale of the moire?