Timed words use birth time and optional lifespan. PlantTimeline.evaluate(time)
reconstructs state directly at absolute time, so playback and backward scrubbing
do not simulate intermediate frames. Events enumerate births and deaths.
Built-ins include constant, linear, inverse-linear, smoothstep, smootherstep,
exponential, ease-in/out/in-out, and normalized logistic curves. Keyframes,
piecewise curves, and registered custom functions cover specialized growth.
GrowthHandle outputs length, radius, curvature, leaf/flower opening, organ
scale, visibility, tropism, and metadata channels.
PartPlantRenderer.setGrowth accepts raw normalized developmental time. It
precomputes cumulative root-to-tip path spans, smooths each segment within its
own span, and keeps partial cylinders attached to their base. Organs begin only
after the segment they reference has matured, so frozen stages remain connected
instead of uniformly shrinking the completed plant.