exitFade property
Dissolve span (0..1) — a leaving contour's ALPHA fades to nothing over
the last 1 - exitFade of the whole animation. This is the whole
vanish. Default 0.75 = a quarter of the morph, ≈160 ms at the default
duration.
Two things make it read as a fade rather than a cut, and both are easy to get wrong:
- It ends at the dot horizon, not when the length runs out — the moment this contour's shrinking ink would stop reading as a line and start reading as a round-cap dot. Nothing is drawn past that. Fade to the end of the exit instead and the dot is still on screen at 30–70% alpha. The span is therefore honoured but slid earlier, per contour, by that contour's own length.
- It is measured in real time, not in exit progress. Progress is smoothstepped across the contour's window, so a quarter of progress lands where the smoothstep is moving fastest — 43 ms, under three frames. A quarter of the timeline is 160 ms.
Alpha, not weight, is what can remove a stroke without unbalancing the glyph — see taperFloor. 1 = no fade (a hard cut when the length runs out).
Implementation
final double exitFade;