SpiralTrajectory

extends Path

The SpiralTrajectory class represents the Archimedean spiral curve a SpiralLayout places its children along – a pure visual guide, drawn from the same radius(t) = startRadius + radiusStep * t, angle(t) = startAngle + direction * angleStep * t formula the layout itself uses, just sampled densely instead of once per child. It never affects layout or data, and it recomputes automatically whenever the collection’s children are repositioned (e.g. after the data or the layout’s parameters change). To create a SpiralTrajectory, use the trajectory method in the Scene class, passing the laid-out collection (or any mark inside it):

let traj = scene.trajectory(collection);

Properties#

property	explanation	type	default value
collection	the collection whose spiral layout this trajectory traces	Collection
extendPastLast	how many extra “child steps” worth of curve to draw past the last child (e.g. 1 continues the curve exactly one more step outward)	Number	0
id	the unique id of the trajectory	String
points	the sampled {x, y} points making up the curve	Array
samplesPerStep	how many points to sample between consecutive children – higher looks smoother but produces a longer d string	Number	12
type	the type of the trajectory	String	“trajectory”

Properties inherited from Path#

property	explanation	type	default value
bounds	the bounding rectangle of the trajectory	Rectangle
fillColor	the fill color of the trajectory path	Color	“none”
strokeColor	the stroke color of the trajectory	Color	“#bbb”
strokeDash	the dashes and gaps for the trajectory stroke	String	“none”
strokeWidth	the stroke width of the trajectory in pixels	Number	1

Methods#

Note that the trajectory is drawn behind the collection’s own marks (so points/icons placed by the spiral appear to sit on top of the curve), and only SpiralLayout is supported – CircularLayout’s “trajectory” would just be the circle implied by its evenly-spaced points, which is rarely useful as a drawn guide.