overlays / light-sweep-pass

Light Sweep Pass

A traveling key light re-shades a slotted scene: a soft diagonal gradient band crosses the frame once while every per-element highlight and shadow shifts in lockstep (all driven by one --light-x property), then the light settles into a resting key. Quiet, expensive-feeling; the scene itself never moves. Callers fill the named scene slot; a token hero-and-cards default renders when it is left empty.