traceTaperedStroke

Trace a scribble as a *tapered* ribbon rather than a stroked line.

A laser trail whose tail thins out cannot be drawn by stroking a polyline — a stroke has one width for its whole length. So the outline is walked: down one side offset by the half-width at each point, back along the other. The half-width is scaled by the point's position along the stroke, which is what produces the taper.

SEMANTICS-ASSUMED: the taper profile. The docs say a scribble may taper but not how; a linear ramp over the first fifth of the stroke reads as a trail with a point on it at every speed, and degenerates to a constant width when taper is false.