Physics type v1 — Letter drop
Letters rain down one by one, tumble under real gravity and pile up on a floor line — a drop replayed as a pure function of the loop clock, so every pass lands identically.
The letters of a phrase rain down one by one under real gravity, tumble, and pile up on the floor — the endlessly re-watchable "dump the type" loop.
Physics doesn't loop on its own, so the whole simulation is a pure function of the loop phase φ = animation.progression ∈ [0,1): φ maps to a step count, and the sketch advances the Matter world to exactly that many fixed-dt steps every frame. Because the layout is laid out from a fixed seed and Matter is deterministic, the same φ always yields the same frame — so the recorded clip is reproducible and the live preview, the scrubber and the export all agree.
The stepping is cached and incremental: normal forward playback advances one step at a time (O(1) per frame); only a phase REWIND (the loop wrapping from ~1 back to 0, or a manual scrub backwards) rebuilds the world from zero and fast-forwards to the requested step. The loop reads as: empty → letters rain and settle into a pile → hold on the settled pile → cut back to empty.
