Punctual feedback (fb) with gain at or above 1 blooms to white and requires re-evaluation to reset

The fb node in Punctual reads the previous frame’s output, enabling feedback trails. If the gain applied to the fed-back signal is >= 1, it amplifies rather than decays, causing an exponential bloom to white (or to clipped noise in audio). Once runaway occurs, it cannot self-correct — the only reset is re-evaluating the program (which restarts the feedback buffer). To avoid runaway: keep the multiplier on the fed-back signal below 1 (commonly 0.95–0.99 for long trails), and prefer compositing via >> mul or blend with a decay, giving a controlled decay rate.

Examples

0.98 * fb frt >> add; — controlled decay trail. fb frt >> add; (gain = 1) — eventual white bloom.

Assessment

Write a Punctual feedback expression that creates slow-decaying trails with about 20 frames of persistence, then explain how to choose the gain value.