linear mask
A clean horizon drawn through the frame. One world on this side of the line, another on that side — and a seam you can slide, tilt and feather until the cut feels inevitable.
What it’s for
Every diptych painter and split-screen editor reaches for the same instinct: hold two ideas in one image and let the divide itself carry the meaning. The linear mask is that divide. It runs a gradient between two points along an angle you choose, so a single frame can carry “day on one side, night on the other” without ever cutting away.
The seam is the whole point. start and
end set where the transition begins and where it
completes; the band between them is the feathered handover
where one treatment dissolves into the next. Set
angleDeg and the line tilts — a level
horizon, a raked theatre rake, a slow diagonal wipe that never
announces itself as a wipe.
Reach for this when: you want a before/after reveal that lives inside the shot; a title card that grades warm on the left and cold on the right; a slow tonal sweep that crosses the frame like a passing cloud rather than a hard edit.
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
| Key | Range | Default | Effect |
|---|---|---|---|
angleDeg | 0–360° | 0 | Gradient direction |
start | 0–1 | 0.2 | Where the gradient begins |
end | 0–1 | 0.8 | Where it reaches full |
Pairs well with
- color grade — warm on one side of the seam, cold on the other. The whole frame becomes a single held breath between two moods.
- text-glitch — the headline stays clean above the line and disintegrates below it. A thought catching fire as it sinks.
- scanlines — analogue interference creeping in from one edge like weather rolling across the frame.
- chromatic aberration — colour stays true on the calm side and frays toward the seam. The look of an image splitting along its fault line.