tracked mask

What it’s for

A follow-spot operator in a theatre has one job all night: keep the circle on the actor, no matter where they walk. The tracked mask is that operator, automated. It draws a radial gradient around a motion-tracked point and reads the point’s position fresh every frame, so the soft pool of attention chases the subject and never cuts away.

radius sets how wide the pool is — a tight interrogation circle or a generous wash. softness feathers the edge so the boundary breathes instead of cropping. The centre isn’t a parameter you set; it’s a parameter the tracking system supplies, frame after frame.

Reach for this when: you want a spotlight that chases a face across the frame without ever cutting to a tighter shot; film-noir interrogation energy; an effect that stays glued to a moving subject through a whole handheld take.

Where it lives in the app

Add from the Masks panel. The mask appears as its own layer on the timeline; assign it to one or more effects by setting their target to point at this mask layer.

Parameters

Drive it from a tracking point

Bind the mask to a tracking point so the pool follows a moving face every frame:

const mask = player.getMaskLayer('subject')
const track = player.getTrackingPoint('face')

mask.setEvaluator((frame) => {
  const { x, y } = track.sample(frame)
  return { cx: x, cy: y, radius: 0.25, softness: 0.3 }
})

Pairs well with

• radial mask — the static cousin. Use radial for a fixed stage spot, tracked for the one that walks with the actor.
• chromatic aberration — clear vision on the subject, eye-strain everywhere else. The frame strains to keep up with the chase.
• text-glitch — a name stays legible only while the spotlight is on it, then frays the moment attention moves on.
• phosphor CRT glow — burn-in that trails the moving pool, like a camera that can’t forget where the subject just was.