Layer VFX

Overview

An effect is not an illustration of magic. It is a short, isolated piece of motion that an engine layers over gameplay, so it has to arrive with nothing around it, on a background the engine can remove, timed so a player reads it in a fraction of a second. Most failed effects fail on one of those three, not on how they look.

The route is: design the effect as a still, animate the still into a short clip, then pull frames from the clip into a flipbook. Generation mechanics and the spend gate are in the

layer

skill; motion prompting is in

layer-video

pack_sprite_sheet

is named outright below because it is Layer's deterministic packing utility, a tool rather than a model, with no alternative to discover.

If a sibling skill named here is missing from your available skills, ask the user to install it (

npx skills add layerai/skills --skill <name>

); unattended, proceed from tool schemas and flag the gap.

Quick reference

Need	Do this
Fire, magic, light, sparks	Solid black background, for additive blending
Smoke, dust, debris, ink	Flat key colour, then remove it per frame; these need real alpha
The look	`text_to_image` still, one effect, centred, nothing else in frame
The motion	`image_to_video` with the still as `first_frame`
A looping effect	`loop` capability, the same still as `first_frame` and `last_frame`
A locked camera	`video_effects: [{type: "STATIC"}]` where the model exposes it, and say it in the prompt
Frames out of the clip	The clip's `file_id` in an image slot with `video_frame_seconds` , one run per frame
The flipbook	`pack_sprite_sheet` with the frames' `file_ids` in play order

Background decides the blend

Engines composite effects one of two ways, and the background has to match.

Additive (fire, lightning, glows, magic trails, sparks): the engine adds the effect's colour to the scene, so pure black vanishes. Ask for "pure black background, no floor, no environment, no ground glow". Black here is a feature, not a placeholder, and removing it would destroy the glow falloff.
Alpha-blended (smoke, dust, rubble, water splashes, dark magic): these darken or occlude, so black cannot stand in for transparency. Generate on one flat key colour that does not appear in the effect, then remove it frame by frame with a
```
background_removal
```
model. Wispy edges suffer, so prefer dense, defined shapes for these effects.

Do not promise transparent video. Nothing in a video run's schema delivers an alpha channel, so transparency is made on the extracted frames, not on the clip.

Isolate and centre

One effect per run, centred, fully inside the frame with margin on every side. A fireball that leaves the frame cannot be repositioned in an engine, and a second effect in frame has to be cut out by hand. Say it: "a single effect, centred, entirely within frame, nothing else in the image, no characters, no scenery".

Effects are seen small and fast: one bright core, one readable shape, one colour that says what the effect does.

Timing reads

A one-shot effect has three phases, and the prompt should name all of them with rough timings: anticipation (a gather or charge), burst (the peak, fast), dissipation (falloff to nothing). An effect that starts at full intensity reads as a glitch, and one that never fully fades leaves a ghost on its last frame. End one-shots on empty black.

Loops (auras, portals, torch flames) have no beginning or end: cyclical motion only, and the loop capability. See

layer-video

for why prompting "looping" alone produces a clip that jumps at the seam.

Frames out of the clip

Any image slot (

init_image

reference_image

first_frame

last_frame

) accepts a video

file_id

and takes one frame of it, chosen by

video_frame

(

first

middle

last

) or by

video_frame_seconds

, which overrides it. Space the timestamps evenly across the clip: eight to twelve frames is a typical flipbook. Each frame is one run of whatever model receives it, so give the frame a run that does useful work anyway: background removal for alpha-blended effects, an upscale when the clip resolution is too low. Use

batch_size: 1

, since the default is four.

Some frame-extraction models take an

init_video

and a

frame_extraction_location

instead;

get_base_model

says which inputs a model requires.

Frames from one locked-camera clip are already registered, so

pack_sprite_sheet

keeps them aligned: it centres each frame at its own scale in one cell size. Do not trim frames individually first, or the effect will jitter.

Worked example

"A fireball impact for our top-down RPG, as an 8-frame flipbook."

```
list_base_models
```
with
```
filter.use_case: "text_to_image"
```
, first result. Prompt: "Game VFX, a single fireball impact at the moment of burst, orange-white core, licking flames, flying embers, centred, entirely within frame, pure black background, no ground, no scenery, top-down view." Approve one.

list_base_models

with

filter.use_case: "image_to_video"

and

filter.capabilities: {fixed_duration: true}

;

get_base_model

on the first result to see which frame slots and

video_effects

it takes.

Motion prompt with phases: "A small ember gathers for a quarter second, bursts outward fast, then flames and embers dissipate to nothing by the end. Locked-off camera, black background throughout." Pass the approved still's
```
file_id
```
as
```
first_frame
```
,
```
video_effects: [{type: "STATIC"}]
```
if supported, a short
```
duration_seconds
```
.
Price the job as a whole: the video plus eight frame runs, each estimated as the run it will be. Over 20 CUs, ask and wait for an explicit yes.
Execute, poll at
```
poll_interval_seconds
```
. Pull eight frames at evenly spaced
```
video_frame_seconds
```
, each into an upscaling run at
```
batch_size: 1
```
. Keep the black.
```
pack_sprite_sheet
```
with
```
file_ids
```
set to the eight frames in play order and
```
columns: 4
```
.

Common mistakes

Removing the black background from an additive effect, which deletes the glow.
Using black as the background for smoke or dust, which then cannot occlude anything.
A scene, floor, or character in the frame around the effect.
An effect that clips the frame edge.
A one-shot with no anticipation, or one that never fully fades.
Promising a transparent video.
Trimming frames one by one before packing, so the flipbook jitters.
Leaving
```
batch_size
```
at four on per-frame runs and paying four times.

layer-vfx

NPX Install

Tags

SKILL.md Content