Old behaviour: plane.x mapped 1:1 to cursor.x — moving the mouse left
made the plane reverse. New behaviour: every pixel of cursor travel
(any direction) increments a progress counter from 0 to 1, the plane
position is derived from progress, and progress saturates at 1 — so
once the plane has exited stage right, it stays gone.
FULL_DISTANCE = 3500 px of cursor travel for a full traversal. The
existing lerp (0.06) still smooths the rendered position. Background
parallax still uses raw cursor X/Y (independent of plane progress).
deviceorientation handler updated symmetrically — gamma+beta deltas
push progress forward on mobile.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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