Red Paper-cut — our demo

One example among many. Don't reuse its story, arc, shots, props or timings.

Demo: Nian Comes to Town (49 s) · papercut-red.mp4 · source in demo/

Story & structure

New Year's Eve: the monster Nian comes into the village and every house puts out its lights. A little girl folds a sheet of red paper three times and makes one cut; the unfolded rosette goes on her window, a candle is lit, eight cut lanterns fly to eight dark windows and the whole village lights up again; the scraps she cut off become firecrackers, and Nian runs from the red light and the noise. At dawn the camera pulls back: the whole film was one window flower pasted on a real window.

Choose a story where the craft of cutting paper is the plot, use several native moves, and make one of them the cause of the ending, not decoration. Here the fold – cut – unfold is the cause: one lantern cut in the wedge = eight lanterns in the rosette = eight houses lit.

Adapting any topic: find the one thing that gets cut and make its unfolded form the answer (a product's silhouette folded into a wedge that unfolds into all its uses; two lovers cut from one folded sheet; one house cut in a folded strip that unfolds into a street). Treat these as examples of the fold move, not as a required structure.

Arc (40–55 s; 49 s here): cold open on the scissors (0–3 s) → title → peaceful world → threat (the world goes dark and silent) → a quiet decision → fold–cut–unfold on the downbeat → the pattern becomes light and fixes the world → dawn → scale reveal.

Native moves spent: fold – cut – unfold (the climax), holes are light (the backlit rosette on the window, its pattern projected across the snow onto Nian's face), symmetry replicates (the rosette's lanterns fly off; small rosettes unfold as fireworks), scraps have a future (the offcuts come back as firecrackers), everything is one flat sheet (the sawtooth ridge of the far hills stands up and is Nian's back; the final pull-back to the window).

Shots

120 BPM, 2/4: one beat = 0.5 s, one bar = 1.0 s.

Score structure

Original score (demo/music/score.py), D gong pentatonic (D E F# A B), 2/4 at 120 BPM, a 4-bar original theme. Instruments: pluck:pipa (melody + tremolo), dan_tranh / dan_tranh_trem (as zheng / yangqin: broken chords, glissandi, tremolo), erhu (counter-melody, glides), flute as dizi, woodblock (beats, folds), gong2:small (phrase heads and tails), gong2:big (only once, at 31.0), frame_drum. No piano, no string section, no opera gongs-and-drums or suona (to keep clear of shadow-puppet and ink-wash).

Music ducks ~8–9 dB under the voice; downbeats avoid the first word of a line.

Foley specific to this film: Nian's cardboard steps (55 Hz + low noise, each with a ~6 px frame shake), his breathing (low-passed noise), a dazzled whimper (an erhu sample pitched down and low-passed); candles out ("puff") and lit (match + whoomp); fireworks = rising whistle + boom + crackle + falling scraps; a long paper peel at dawn; two bird chirps.

Voice: a warm grandmother telling the story on New Year's Eve, Kokoro af_sarah, speed 0.9, five lines:

Whisper hears "Nian" as "Nyan"/"Nion", the correct pronunciation of nián, so it is registered as an asr alias in lines.json.

Palette & props

• Heroes and window flowers #d2201f; Nian one step deeper #b00f26; near limbs one step brighter #c4162c, far limbs darker (#8a0c20, girl #b8191b); fold back colour #de3b30.
• Rice paper #f2e8d0, night paper indigo #1c2446, ink sky #0f142a, gold foil #d9a93f only at the end (sun, title flecks).
• Night: far hills #1f2a55, near hills #29356e, houses #35457f, trees #28346c, snow #7a88ba, all indigo papers; only window flowers, lanterns, the girl and Nian are red (a red background too makes the silhouettes stop popping). Day: rice-paper sky, red houses, far hills #e0877f, mid hills #cf4f4a.
• Paper shadow: offset 2.6/3.6 px, blur 5 px × zoom, rgba(52,6,10,.38). Inset contour: a 1.5-unit slit 3.5 units inside the outline. Night ambient ~rgb(214,214,236); bloom 10 px / 40 px at strength ≈ 0.55.
• Backlit window flower: radial light #fff6d6 → #ffc46e → #ec782e, rice-paper fibres multiplied at 50 %, the rosette's transmission sprite in #b51d18. Projected pattern squashed onto the ground with [1.25,0,-0.9,0.3].
• The rosette: middle ring yang cut (lanterns, ruyi scrolls on the fold lines, sawtooth on the ring edges), inner and outer rings yin cut.
• The girl: head, coat, 2 × (upper arm, forearm + hand), 2 × (thigh, shin + shoe), scissors (2 blades on a rivet); face pieces smile ∩, surprise, scared, determined almond eye, asleep ∪; cheek rosettes.
• Nian: body, head (big, ×1.32), hinged jaw, mane, tail, 4 × (upper leg, lower leg + paw); sturdy legs with four curved claw tips and swirl knee joints (no crescent-striped shins). When the light hits him, pattern + solid warm spot are added inside his layer, so the squint and big tears are holes that read on the lit face (the gag); unlit parts darken to silhouette.
• Cutting: reveal circles r ≈ 62 units; blades open/close every 0.25 s (each snip = one eighth note); the camera holds the tip at ~32 %. Each fold ≈ 0.55 s on a woodblock; three unfolds 0.25 s apart.

End card

Couplet strips slide in beside the window, a red banner with cream cut letters "RED PAPER-CUT" drops in above, gold-foil flecks, and the credit line "LemoLab × Claude Opus 5.5" below in ink. The "LemoLab × Claude Opus 5.5" sign-off belongs to this library's demo only; a user's film carries no LemoLab credit and no copy of this card.

Title and subtitles as built: cut letters in Fraunces 800 on rice paper with sawtooth border strips, a red seal with the character 年 cut as a hole, an italic subline. Subtitle banner #a8111f, gold flecks, Fraunces SemiBold 44 px in cream #fff1d6, centred 70 px from the bottom, hold ≥ voice + 0.7 s and ≥ 1.8 s.

Build notes

styles/papercut-red/demo/
  paper.js    paper textures, piece builder (fill, cut, inset, edge, grain), shadows, transmission
  motifs.js   folk pattern library          rig.js      2D affine rig helpers
  girl.js     jointed girl + face pieces     nian.js     jointed monster + eye pieces + poses
  tuanhua.js  8-fold rosette (one wedge × D4) village.js  houses, hills, plum tree, snow, lanterns
  light.js    night lightmap, backlit windows, bloom, rays, masked projected light
  world.js    village layout (night/day palettes) + lighting pass
  fold.js     fold – cut – unfold sequence   hud.js      subtitle banner, cut-letter text
  story.js    timeline (single source of truth, 120 BPM)   main.js  shots, cameras, events
  sheet.js / climax.js / test.js   model sheets and style frame (?test=sheet_girl | sheet_nian | frame)
  lines.json  voice script   music/score.py  original score   mix.py  foley + voice + music   subs.py  srt

1. node core/render/still.mjs styles/papercut-red/demo <t…> [--q nosub=1]: review stills; ?test=sheet_girl etc. for model sheets.
2. .venv/bin/python core/tts/tts.py lines.json voices → core/tts/asr_check.py until all OK.
3. node core/render/events.mjs → music/score.py → mix.py → subs.py.
4. node core/render/video.mjs styles/papercut-red/demo --fps 24 --workers 3 (1176 frames, ~30 s).
5. sh core/render/mux.sh out/video24.mp4 mix.wav papercut-red.mp4 24 0, then check_final.py (per-line whisper on the final mix + blackdetect). Or simply sh styles/papercut-red/demo/build.sh.

Engine traps: put() uses setTransform, so it ignores an enclosing translate: pass absolute matrices. Test-mode pages must not throw to stop the module (the render harness exits on any page error): guard the window.render assignment instead. Engine numbers as used: paper grain mottling ±7 % at ~130 px; edge wobble ≈ 0.35 units; sawRow, sawEdge, crescent / crescentRows, swirl / doubleSwirl, cloudCut, rosette, plum, coin in motifs.js; half-res bloom blurs; don't smooth the houses: smoothing turns them into bread loaves.

Pitfalls tied to this demo's props: - Don't store the wall height in a house piece's p.h: it stretches the house (x0,y0,w,h is the drawing box). - Don't darken the snow layer through the light map: it makes ghost legs visible through the snow. - Check that the folding scissors point forwards, not backwards. - Centre the projected pattern on Nian's snout with a solid warm spot, not on his eye: on the eye it hides the eye; on the snout the squint and tears read. - The cold open's flying sheet overlaps the title card to avoid blank frames.