Trail
Connect each point's recent positions into a motion trail, one per @id.
What it does
Trail records each point's recent positions and connects them into a streak, one per @id. Length sets how many frames of history a trail keeps, and anything older falls off the tail.
Render Mode picks the form: Path is a flat 2D filled path, Tube is a 3D spine swept into a pipe, one per trail. Analytical decides whether the result stays a resolution-independent analytic shape or is swept into a mesh for the 3D scene. All four combinations are real.
When to use it
Motion streaks behind particles, a fluid, or a flow field.
A drawn path taken from something that moves, ready for Trim Path or Stroke.
A 3D ribbon or pipe following a moving point cloud: Render Mode set to Tube.
| Parameter | Type | Default | What it does |
|---|---|---|---|
source | Collection | — | What to trail — any moving geometry (points/geometry/CRC, or a field/raster sampled to points). A stable @id per point, e.g. from Spawn, gives one streak per point. |
length | Number | 20 | How many frames of history each trail keeps (streak length). |
stroke | Color | rgba(1.00, 1.00, 1.00, 1.00) | Trail stroke color (linear RGBA). |
stroke_width | Number | 2 | Trail stroke width at the head (newest point). |
taper | Number | 0.500 | How much the trail narrows toward its tail (0 = uniform, 1 = tapers to a point). |
render_mode | String | "Path" | 2D filled path (Trim Path / composable) or 3D tube spine, one tube per trail (preserves Z). One of: Path, Tube. |
analytical | Boolean | true | Analytic: emit a resolution-independent CRC trail (composites as a flat 2D layer). Turn off to sweep the trail into a Geometry mesh for the 3D scene. |
opacity | Number | 1 | Layer opacity (0 = transparent, 1 = opaque). Editable, wirable, keyframable. |
Gotchas
A stable @id per point is what separates one streak from another. Points from Spawn and from the simulations carry one. Without it every point shares id 0 and the trails merge into a single streak.
Trail builds its history as frames run, so a freshly placed node shows nothing until Length frames have played.
Taper narrows a streak towards its tail. There is no fade: neither form carries a per-anchor colour, so a trail is one colour along its whole length.
A Path trail is always drawn at the origin and unfilled. Its position and fill come from parameters the node does not expose, which fall back to their defaults. Place it with a transform downstream.
Worked example
Wire a moving point cloud into Source, from Spawn or a simulation.
Raise Length for longer streaks.
Set Stroke and Stroke Width for the head, and Taper for how sharply the tail narrows.
Switch Render Mode to Tube and turn Analytical off to sweep a real mesh for the 3D scene.