Claude Opus 5.5

# Art Deco — Style Prompt > Black lacquer, engraved gold line and airbrushed geometry: a 1930s poster that moves. Every composition has a centre axis, transitions open or close along it, and light arrives as bulbs switching on one by one. > References (grammar only): **A. M. Cassandre** posters (giant geometry, steep perspective, airbrush inside hard edges); **Chrysler Building / Rockefeller Center ornament** (setbacks, sunbursts, chevrons); **Busby Berkeley** overhead numbers overheads (human kaleidoscopes); **The Great Gatsby (2013) title sequence** (gold line drawing itself on black); **Gershwin-era symphonic jazz** (clarinet, piano, muted trumpet). Never copy a poster layout, a real building, a character, a typeface design or a melody. ## 1. Essence, and what it is not A world built from **gold keylines on warm black**, filled with **airbrushed hard-edged volumes** (Cassandre, Lempicka), organised around **one vertical axis**. Ornament *is* the picture: sunbursts are backgrounds, stepped arches are frames, a dial is a progress bar, a bulb marquee is a reveal. Motion is **mechanical and symmetrical**: things unfold from the centre, doors split along the seam, lights switch on in counted order. Native register: glamour with a clock ticking (an event, a deadline, a launch). Not a gold-foil slideshow (things move and have volume), not Art Nouveau (no whiplash curves, no flowers), not a flat vector poster (volumes are airbrushed and rimmed), not a 60s spy title (no silhouettes on flat colour). ## 2. Materials & rendering - **Ground**: warm lacquer black, never neutral grey-black; a night sky may drift toward a deep emerald near the horizon. - **Gold is a banded metal gradient** (dark – light – hot – light – dark); animate its `sheen` offset for a light sweep. - **The signature stroke** (`gline`): a dark engraved underline ~1.6 px wider than the line, the gold gradient line, and a hairline highlight on top. Optional glow and a parallel twin (`double`). Nothing gets a black cartoon outline. - **Volumes**: hard edge + airbrush (`airbrush`): a directional gradient from shade to light inside the shape, one consistent light direction (upper left by default), a thin gold rim on the lit side. - **Motifs** (sunburst, stepped arch / ziggurat, fish-scale, chevrons, fan, four-point sparkle, speed lines, clock face, dial) are structural (a background, a frame, a transition), not stickers. - **Perspective is real**: true one-point (mode-7 floors) and two-point perspective through a pinhole camera, so dolly, tilt and pan change perspective instead of scaling flats. - **Characters are deco too**: about 7 heads tall, tapered streamline bodies, faceted lacquer planes (Lempicka), almond or arc eyes, a one-stroke nose, airbrush + gold rim. Give each lead one or two silhouette marks readable at a quarter of frame height. ## 3. Colour logic - Three constants: **warm black ground, gold line and metal, ivory** for paper, gloves, light and type. - **One saturated accent reserved for the protagonist** (or the one object the story follows). It is the only large saturated area, so the eye finds it in any wide shot. A cooler jewel tone may carry secondary surfaces, never competing in area. - **The one-colour exception**: any single element can be drawn in its own colour through the same fill + keyline + glow (`color` option) while everything else stays gold. - Always expand hex to six digits in code (three-digit hex breaks colour mixing). - Examples of the triad (accent / jewel / metal): burgundy / emerald / gold; coral / sapphire / pale gold; jade / plum / rose gold. Our demo's actual values are in DEMO.md. ## 4. Type & subtitles - **Type (OFL)**: Limelight (titles), Poiret One (numbers, sign skeletons, plaques), Josefin Sans (subtitles, labels), Italiana (numerals). - **Titles are architecture**: a stepped gold title bar over an arch or sunburst, optional badge and wings; drawn on in gold, then a sheen sweep. - **Subtitle card** (`subtitleCard`): a lacquer bar (~88 % black) with stepped ends like the title bar, double gold keyline, Josefin Sans SemiBold ~40–42 px ivory, an optional small speaker icon per voice. It **unfolds from the centre** like every other title, so titles, subtitles and transitions are one system. Hold ≥ max(1.8 s, speech + 0.6 s). - Numbers carry plot without narration: dials, clock faces, floor medallions, badges. ## 5. Motion quality - **Characters step on twos (12 fps)**; camera, light, bulbs, gold draw-on and sheen run on ones (24 fps). A stepped camera reads as stutter. - **Everything unfolds from the centre**: a point → a hairline → bars open symmetrically → text rises → wings and sparkle. - **Draw-on follows the music**: a gold line grows at the speed of the phrase under it and lands on the hit. - **Bulbs have an ignition overshoot** (~1.6× flash settling in ~0.18 s) and a relay "chunk"; once a sign is lit, a fast chase may run across it. - **Mechanical easing**: doors, dials and hands move with firm ease-in-out and a small settle, like machinery; nothing floats. - **Performance beats get anticipation** and escalation in threes (once, twice, mash). - What never moves: the centre axis of a composition. Symmetry may rotate or open, but it never drifts off-centre. ## 6. Camera grammar A vocabulary, not a route. Opening and ending come from the topic. | Move | What it expresses | Can serve | |---|---|---| | Symmetric split (two door leaves hinged at the edges; or a revolving-door wipe) | a threshold crossed | a new place; a new chapter; a reveal behind a façade | | Leaves sliding shut over the live shot | a door closing on a moment | leaving; a decision made; the end of an era | | Extreme low-angle Cassandre tilt | scale and aspiration | a goal far above; a tower, a rocket, a monument | | Architectural section (pull out to a cutaway of the whole building) | progress through a structure | climbing, descending, a process in stages; a company's floors | | Busby Berkeley overhead, mirrored and rotating | people become pattern | a team, a release, a celebration, a system of parts | | Push-in on a dial, medallion or clock | the number is the plot | a deadline; a count; a milestone | | Match-cut on shape (circle → circle, ray → ray) | two places, one rhyme | jumping between departments, cities, eras | | Low oblique along a sign or marquee | light travelling letter by letter | a name revealed; a launch; a score being counted | | Pull back from detail to skyline | where the moment sits in the world | aftermath; a city-wide effect; scale | Framing: the centre axis is sacred; an asymmetric frame must resolve to it within the shot. At an emotional peak the protagonist fills ≥ ~1/3 of frame height (smaller, the face reads as a prop in the ornament). Transitions: splits, revolves, arch openings, shape matches; never a generic dissolve or slide. ## 7. Sound palette - **Symphonic jazz of the 1920s–30s, not a 60s big band.** Options: stride or concert piano, clarinet (trill; a glissando by time-varying resampling of a long note), strings (tremolo, rushes, pizzicato), muted trumpet commentary, trombone and sax section, walking pizz bass, brushes or sticks, tubular bells, harp glissandi, banjo, xylophone runs, celesta. - Rhythm families to choose from: foxtrot, Charleston, tango, a slow torch-song ballad, a fanfare in the manner of a newsreel. - **Techniques (options)**: one hit per unit of counted light; accelerate by dividing the beat; plant a theme in fragments so its full statement is a payoff; low-pass a band that is physically far away and open it as we approach; move a period narrator through acoustic spaces (horn, radio, PA, live mic) to make distance audible. - **Foley by material**: brass clicks, bronze clang + chain, iron treads, marble heels, silver trays, wooden doors + spring twang, paper flutter, knife-switch "chunk" + filament hum, relay ticks, elevator ding, champagne cork. - **Silence as a tool**: before the most important sound, drop to one small diegetic sound (a clock tick, wind) and cut back in with that sound alone. - **J/L-cuts** carry architecture: the next room's sound enters a bar before its door opens. - Mix: duck music ~−9 dB under voice (less under a period announcer who is part of the texture), beds −6 dB, −14 LUFS, light film grain. ## 8. Native moves A menu: use the ones your story needs. - **Counted light.** A bulb sign lights one letter per beat or per event, so the audience can count. *Fits content like:* the countdown to a product launch; the letters of a city name lighting as a train arrives; votes tallied into a winner. - **Threshold doors.** Every scene change is a door split along the seam. *Fits content like:* the departments of a company; the rooms of a museum; stages of a career. - **Machine kaleidoscope.** People or objects become a mirrored, rotating pattern that locks into a symbol. *Fits content like:* a team becoming a logo; gears of a supply chain; a choir becoming a clock. - **Dials carry the plot.** A floor indicator, a clock or a gauge moves instead of narration. *Fits content like:* a funding thermometer; the altitude of a climb; a stock ticker at the opening bell. - **The architectural cutaway.** Pull out until a building is a section and the protagonist a coloured dot with speed lines. *Fits content like:* data moving through a server stack; a letter through a post office; a skier down a resort. - **Sheen sweep / draw-on.** Light crosses a gold object on a hit; a gold line engraves itself at the speed of a glissando. *Fits content like:* unveiling a trophy; a map route; a signature on a treaty. - **The one colour.** One element keeps its own colour in a gold world. *Fits content like:* the one product among competitors; the patient among doctors; the new idea in an old firm. ## 9. Pitfalls of the medium - Bulb signs from glyph skeletons break on curves (G, S, R): Zhang–Suen staircase pixels fool a neighbour-count junction test → use the **crossing number** and weld chain ends within ~14 px. - A generic cartoon character looks pasted in → characters are deco (§2). - Fish-scale reads as brickwork → lower half-circles row by row, each overlapping the previous row, plus an inner arc. - Door leaves over a flat "interior" read as a blank frame → draw only the leaves, closing over the live shot. - A gold point on pure black trips `blackdetect` → lift the background wedges and glow slightly. - Period loudspeaker distortion is unintelligible under music → gentle drive; whisper-check every line on the final mix. ## 10. Engine Canvas2D, deterministic in `t`, in `demo/engine/`: `deco.js` (gold gradient, `gline`, `airbrush`, motifs, `drawShape` for any path in the deco manner, `color` for the one-colour exception), `type.js` (title bar, digits, badges, dial, clock, `subtitleCard`), `bulbs.js` (any text → bulb sign, `litSequence`), `cam.js` (pinhole camera, `cardTransform`). `demo/frames.js` renders model sheets and style frames from the real engine. Signatures and a minimal example that draws something not in the demo: DEMO.md "Engine reference". ## 11. Variation space You decide the structure, the characters (or none), the settings, the opening, the ending, the camera path, the pacing, the accent colour and what gets counted. All far from our demo: - Structures: **the exhibition** (five pavilions of a world's fair, one idea of the topic behind each door); **the ocean liner** (three decks from engine room to ballroom, a horn per stage); **the trophy night** (nominees as sunburst panels, the winner revealed in light). - Openings: **the machine room** (gold gears and pistons building to the first beat); **the engraved map** (a gold route crosses a continent before anyone appears); **the telegram** (ticker tape types the premise). - Endings: **the lights go out** (letters switch off in reverse until one bulb remains); **the dawn** (lacquer black warms to a pale sky); **the poster** (the last shot flattens into a printed poster with a date). --- How our demo was made (story, shots, score, end card, build): [DEMO.md](DEMO.md). Read it after your treatment exists.

# One-line Drawing — Style Prompt > A single ink line that never leaves the paper. Everything on screen is that one line being drawn; scenes don't cut, they morph. > References (grammar only): Osvaldo Cavandoli's *La Linea* (1971) — one line is both the world and the character, and transformations of the line are the jokes and the transitions; Gjon Mili's 1949 photographs of Picasso drawing with light — the confidence and speed of a single gesture; Norman McLaren's *Begone Dull Care* and *Boogie-Doodle* — lines drawn *to* the music. Do not copy La Linea's character, its gibberish voice, or any specific continuous-line illustration. ## 1. Essence, and what it is not - **One continuous line** on warm white paper. The pen never lifts: in code the whole film can literally be one point array, from the first touch of the nib to the last frame. - **Everything is a line**: characters, places, objects, even time. No fills, no shading, no second line weight, no background art. - **We watch the line being drawn**: the camera follows the nib with a little lag and anticipation. - Besides ink there is only the paper and a soft **shadow of the pen** (the real world above the paper). One accent colour at most, used once. Not a whiteboard explainer (no hand, no marker, no erasing, no text-heavy boards), not ink wash (no tones, no brush bloom as a look), not a line-art animation with cuts and many strokes. ## 2. Materials & rendering - **Paper**: warm white (around `#F4EFE4`), procedural mottling (soft-light, large tile), long fibres that fade out when zoomed out (or they shimmer), a sparse paper-tooth speckle over the ink at close zoom, light vignette. All textures anchored to the paper; they move with the camera. - **Ink** is a filled polygon around the path (not `ctx.stroke`), mixed with paper colour to an opaque tone per point. - Width = base width of the current "voice" of the line × pen pressure × fine noise (±8 %); pressure from speed: `0.66 + 0.8·exp(−v/300)` (fast = thin, slow = fat). - The line's character can change along the path (base width, alpha, tremble, dryness); blend over a short stretch at boundaries. - Ink bleed: the same polygon slightly wider, blurred on an offscreen layer, composited at ~20 %. - Pooling: extra round dots where speed drops low. - Tremble (perpendicular noise) and dry-brush gaps (long-scale noise + thin bristle strands) for age, fear or fatigue. - A stop leaves a teardrop-shaped blot: tip at the nib, belly sagging downward as it spreads, a dark tide line at the rim. - **A screen-space minimum width**: widths scale with zoom like a line under a macro lens, but clamp the zoom used for width during pull-backs so a wide view keeps its weight. - **The pen is never drawn**: a soft blurred wedge of shadow from the nib and a tiny contact dot. Hands, if any, appear only as shadows, each hand composited as one flat layer. - **Path design**: chapters written as SVG path strings, sampled by arc length, joined by tangent-continuous connectors; time assigned per point weighted by curvature. ## 3. Colour logic - **Ink on paper.** A warm black (around `#1D1A17`) on warm white; nothing else fills the frame. - **One accent at most, used once**, on a stretch of the line that means something; it returns to ink afterwards and stays visible in the final picture if the picture is revealed. - Examples of an accent's job: red for love or danger; blue for water or cold; gold for money or a prize. Never a second accent. ## 4. Type & subtitles - **Text is written, like the line**: a handwriting face (e.g. Caveat) for subtitles, ink at ~84 %, no box, centred near the bottom, **written on** left to right (~0.2 s + ~17 ms per character) behind a soft paper-coloured halo so passing lines never cross the letters; fade out ~0.45 s. Hold ≥ max(1.8 s, speech + 0.6 s). - Titles in a monoline connected script (e.g. Sacramento: itself a one-line drawing), written on in empty paper away from the drawing, gone before the camera moves into them. ## 5. Motion quality - **Everything on ones** (24 fps): the appeal is the continuous act of drawing; stepping breaks it. - **Timing = chapter windows + curvature**: within a window, time per point is weighted by `1 + K·turn` (sharp turns get more time, smoothed so speed never jumps). Pin musical beats with marks: by arc-length fraction or by position ("the second time the pen passes here"). A stop is two marks at the same place. - Corners (speed minima at high turn) can be exported to the soundtrack as candidate note onsets. - Speeds: ~300–700 units/s for travelling lines, ~50–150 for small details. The most important stroke is usually the slowest. - **Retracing** over an existing line is legal and invisible (it only thickens slightly). ## 6. Camera grammar A vocabulary, not a route. The camera is one continuous move: composition centre, zoom, a few degrees of roll, and a follow weight (0 = composed, 1 = locked to the nib); the follow point averages the nib over roughly −0.55…+0.4 s (lag and anticipation), with a soft clamp keeping the nib inside the central ~70 % of the frame. Opening and ending come from the topic. | Move | What it expresses | Can serve | |---|---|---| | Follow the nib (high follow weight) | travel; momentum; a thread of time | a journey; a process; a timeline | | Composed frame, low follow weight | a scene that must read as a whole | a vignette; a joke; a diagram | | Macro on the nib | intimacy; the act of making | a first touch; a signature; a detail | | Hold with a slow push-in | weight; a stop | a loss; a doubt; a decision | | Mirrored framing | rhyme across time | parent and child; before/after | | Continuous pull-back | everything was one picture | a reveal; a map; a word | | Lateral scroll with the line running ahead | a horizon; a graph; a race | a stock chart; a heartbeat; a road | | Roll with the line | vertigo; play | a loop-the-loop; a fall; a dance | No cuts. Transitions are morphs: the last stroke of one image is the first stroke of the next. ## 7. Sound palette - **Music: one solo instrument, one unbroken melodic line**, the sound equivalent of the drawing: a bowed or plucked string (cello, violin, viola, harp), a solo woodwind (clarinet, flute, bassoon), a hummed voice, a single guitar. A second colour only as a rare accent (a chime, a pizzicato stretch). No pads. - **Write the score to the drawing**: key notes on marks and corners; fast line = short notes; a stopped line = one long note fading into silence; the highest note on the most important touch. - **The pen on paper is the most important sound**, synthesised from the pen speed: band-passed noise (brighter when fast, duller when slow), random paper-fibre ticks with density ∝ speed, amplitude ∝ √speed, panned with the nib's screen position; broken up by dry gaps; lighter and jerkier for a young hand. Plus: a wooden tap on the first touch, a faint wet swell for a blot, a tiny rub for a handoff, a page lift. - **Silence is literal**: zero the music bus including reverb tails; drop room tone. - **Mix**: music ducks ~5 dB and the pen ~4 dB under voice; −14 LUFS; grain 0 (the paper is in the render). - **Voice**: warm, few short lines that leave space for the line; place key words on picture beats with whisper word timestamps. ## 8. Native moves A menu: use the ones your story needs. - **The pen never lifts.** Anything that is one continuous thing. *Fits content like:* a river from source to sea; a relay race; a production line. - **The line is time.** The stroke's character changes with age, mood or strain. *Fits content like:* a building aging; a runner tiring; a machine wearing out. - **Transformation.** One image morphs into the next. *Fits content like:* a seed becoming a tree becoming a table; a sketch becoming a product; a word becoming its object. - **Stopping is an event.** The nib stops, ink pools, music cuts to silence (1.5–3 s). *Fits content like:* a power cut; a pause for a minute's silence; a hesitation before a signature. - **Reverse-designed scale reveal.** Every vignette is secretly part of one big picture seen at the end. *Fits content like:* a city's landmarks forming its skyline; a company's milestones forming its logo; a recipe's steps forming the dish. - **Handoff.** The pen passes to another hand (as a shadow) and a new line begins. *Fits content like:* a teacher and a student; a founder and a successor; one generation to the next. - **Line as graph.** The line becomes a chart while staying a drawing. *Fits content like:* a heartbeat; a temperature record; a football match's momentum. ## 9. Pitfalls of the medium - **Stray connectors ruin a reveal**: every extra line reads as a wrinkle, beard or mask. Fix the topology (where each chapter enters and leaves), not the drawing. Plan it like an Euler path: a closed motif is a circuit (you leave where you came in); retrace or reorder chapters. - Each region of a final picture is drawn exactly once; connectors must fall on natural lines of that picture. - **Test the reveal early and often**: render the whole path at once at final scale after every change. - Lines drawn too close braid together once width is applied; keep a gap. - A round blot reads as a mole → a sagging teardrop. - Thin lines at wide zoom → clamp the width zoom. - Translucent hand shadows double-darken where they overlap → one layer per hand. - Titles collide with the drawing as the camera moves → check every frame of the title's window. - Whisper mishears short lines → rephrase rather than fight it. ## 10. Engine In `demo/`: `geom.js` (samples SVG paths by arc length in the browser, adds tangent-continuous connectors, assigns time by curvature, marks and holds), `ink.js` (the line renderer: pressure, bleed, pooling, tremble, dry brush, accent stretch, blot, minimum screen width), `paper.js` (paper, fibres, tooth, vignette), `cam.js` (composition keys + nib follow + soft clamp), `hands.js` (pen and hand shadows), `subs.js` (written-on subtitles and titles). The drawing itself lives in one file of SVG path strings and a chapter table (`face.js`); replace it with your own path. Debug views (`?all=1`, `?cams=`) render the whole path or many camera views in one session: see [DEMO.md](DEMO.md) "Build notes". ## 11. Variation space You decide what the line draws, whether it reveals one final picture, where it stops, the accent (or none), the opening and the ending. All far from our demo: - Structures: **a line that is a graph** (a data series drawn as a horizon; each peak and trough becomes a scene); **two lines** that start in opposite corners and are drawn in alternation until they meet; **a loop** (the line draws a scene and then retraces its way back to the start, which now means something else). - Openings: **mid-line at speed**, the pen already running across the paper; **a finished drawing** whose line then unravels into the story; **a word written in script** whose last letter becomes the first scene. - Endings: **the line runs off the edge** of the paper and keeps going; **the ink runs out** and the last stroke fades into dry scratches; **the pen stops in mid-air** over the paper before the last stroke. --- How our demo was made (story, shots, score, end card, build): [DEMO.md](DEMO.md). Read it after your treatment exists.

# Whiteboard Explainer — Style Prompt (v2, no hands) > An explainer drawn live on one glossy dry-erase board: single-line handwriting that is actually *written* stroke by stroke, floating markers with no hand, magnets that can move, an eraser that can rewind, and a camera that travels across the board instead of cutting. > References (grammar only): RSA Animate / Cognitive Media (one continuous board, the camera travels instead of cutting, a full-board view); minutephysics (one sentence = one drawing, the simplest geometry that carries the idea); Steve Reich's *Piano Phase* (two copies of one figure at two tempi as a structure). Never copy their drawings, characters, hands or music. Suits explainers of 60–120 s, usually science or "how does X work". ## 1. Essence, and what it is not - **One physical whiteboard.** Everything the viewer learns is drawn in dry-erase marker in front of them, in real handwriting order. - **The board is a map**: each idea lives in its own region; the camera travels between regions, often led by the pen. Distance on the board = distance in the argument. - **Real marker, not animated text**: ink pools where the nib lands, dry streaks and speckle, strokes overshoot and don't quite close, ghosts of old lessons remain, a glossy sheen drifts slower than the board, and **every stroke makes a sound**. - **No hands.** Markers float with a real cast shadow that grows when they lift, park outside the frame between phrases and fly back in. Magnets and the eraser move on their own. Never draw a hand, an arm or a cursor. Not Blueprint (no blue sheet, no drafting conventions), not Crayon Picture Book (no wax texture, no children's story), not a kinetic-type explainer (text is handwritten stroke by stroke, never animated as blocks). ## 2. Materials & rendering - **Board**: a warm white gradient, a faint scuff and micro-scratch tile, a few dozen **ghost marks** (old words, circles, arrows) at 5–10 % in grey or pale blue, and a soft diagonal **window sheen** (white, 10–16 %) moving at ~0.35× the camera: this one detail sells "glossy". - **Ink**: alpha ~0.94, composited with **multiply** so overlaps darken like real marker. Width 6–11 px for drawing, ~13 % of cap height for lettering. - **Stroke character**: resampled every ~0.6 × width; low-frequency hand wobble along the normal (a few px, long wavelength) plus a finer tremor; chisel-tip width modulated by direction; a pressure ramp at the start and a small taper at the end; circles start at an angle and **overlap past closure**; rectangles are four strokes with small corner overshoot; a darker pooled dot *inside* the start of long strokes. - **Dry-marker texture**: a speckle-and-streak tile subtracted from the ink layer (destination-out), locked to board space, faded out when the camera is wide. - **Lettering**: a single-line (single-stroke) font written in stroke order, each glyph with small rotation, baseline and scale jitter. Missing symbols (μ ≈ → × − ✓ ² ° ±) are hand-defined. - **Props**: dry-erase markers (white barrel, colour band and cap in the ink colour, felt nib), a felt eraser, magnets (glossy, with specular highlight and soft cast shadow). Frame, tray and wall appear only if the camera ever goes past the board edge. ## 3. Colour logic - **Three marker colours at most**, each with a meaning held for the whole film: one dark ink for things and structure, one for signals / measurement / process, one accent for the thing that matters (one accent per region). - **Monochrome variant**: everything in the dark ink, one element in the accent (the "only colour"). - Ghost marks and board stay neutral; the accent never appears on props except its own marker cap and the hero magnet. - Example sets: black `#23262c` / blue `#2a5cb3` / orange `#d97757`; black / green `#2e8b57` / red `#c8363a`; navy `#1f2a44` / teal `#1f8a8a` / purple `#7a4fb3`. ## 4. Type & subtitles - **Handwriting only**: a single-line hand (e.g. EMS Tech, OFL) for all board text; titles large (~120–200 px cap height), labels 30–70 px. - **Title and end card are written on the board** in the same hand. - **Burned subtitles**: an off-white rounded label (~90 %), a handwriting-like face (e.g. Architects Daughter ~44 px), dark text, a short accent-colour marker dash. Split at clauses, ≤ 44 characters per line, bottom ~12 % of the frame kept free for them in every shot. Hold ≥ max(1.8 s, speech + 0.6 s). - **Writing finishes on the word**: a term appears exactly when the narrator says it. - A label is fully in or fully out of every shot it appears in. ## 5. Motion quality - **Hand speed**: every stroke follows a slow-fast-slow curve (`u − sin(2πu)/2π × 0.8`). Strokes are scheduled into a **time window** and the engine solves the speed, so writing always finishes on time. - **Pen hops** between strokes lift in proportion to distance (shadow slides and blurs); long gaps send the pen off-frame to park and back shortly before its next stroke. - **Magnet**: drop with a shrinking shadow; slide with a small lift; lift-off and sink possible. - **Eraser**: constant speed along a path, a wide band at ~90 % strength (a ghost always remains). - **Speed**: faster than real hands (a sped-up lesson) but never so fast the stroke order is lost: a label ~0.3–0.8 s, a title ~3 s. - Camera on ones with real motion blur when it moves fast. ## 6. Camera grammar A 2D camera over a large board (e.g. 8000 × 4500): position, zoom interpolated in 1/z so pushes feel like dollies, a little roll. A vocabulary, not a route. Opening and ending come from the topic. | Move | What it expresses | Can serve | |---|---|---| | Pull back from a tiny drawing | scale | a surprising size; context | | Ride the line the pen is drawing | one idea leads to the next | a transition; a process; a path | | Hold still | read now | an equation; a definition; a list | | Whip to a new region | a new idea after a pause | a twist; a "but" | | Return to an earlier region | a callback, for free | reusing a result; a comparison | | Split view of two regions (zoomed out enough for both) | two things at once | a duet; before/after | | Slow push into one symbol | this term is the point | a unit; a variable; a name | | Track along a long diagram | sequence, time | a timeline; a pipeline; a journey | | Pull back past the board edge to the wall | the whole lesson as one picture | a summary; a scale jump | Motion blur: when the camera moves more than ~14 px per frame, render and average sub-frames (≤ 4 px apart). No cuts on the board; if a cut is needed, it is a whip. ## 7. Sound palette - **Every stroke sounds**: band-passed felt-on-gloss noise (a hiss band ~2–7.5 kHz + body ~0.5–1.5 kHz) enveloped by the stroke's own speed curve, a tiny nib tick at the start, stick-slip grains, and on some long strokes the **dry-erase squeak** (a 1.5–2.6 kHz sine with 7–13 Hz vibrato). Each colour sounds slightly different. Pan = the stroke's screen x; closer camera = louder. - **Props**: magnet on steel = click + metal modes + a low board thump; eraser = felt rub modulated by its zig-zag; cap off/on; marker tray bounce. - **Room**: low room tone; a single diegetic ticker (a wall clock, a fridge hum, a projector fan) can own a silence. - **Music** options: a solo piano figure; a small jazz trio with brushes; plucked strings and kalimba; a synth arpeggio for tech topics; clockwork minimalism (marimba, pizzicato, woodblock, glockenspiel). Mickey-mouse details: a rising whistle for growth, pings for signals, a harp run for a fall. - **Techniques to pick from**: adding one instrument per step of a mechanism; a key change when the frame of reference changes; a full stop into silence before a surprise; the previous cue reversed and squeezed for a rewind; two copies of one figure at two tempi (phasing) for anything that diverges, snapping into unison when resolved. - **Mix**: voice on top (compressed, light room), music well under voice and ducked further under speech, foley ~11 dB under voice; −14 LUFS. ## 8. Native moves A menu: use the ones your story needs. - **Writing in stroke order.** The reveal is the explanation: a formula term by term as it is spoken. *Fits content like:* compound interest; the Drake equation; a recipe's ratios. - **The pen leads the camera.** Transitions are drawn lines the camera rides. *Fits content like:* a nerve signal; a supply chain; the water cycle. - **Magnets.** The only things allowed to move on a board: give the hero to a magnet; slide, lift, drop, sink it. *Fits content like:* a delivery truck on a route; a cell in a bloodstream; a player on a pitch. - **The eraser rewinds.** Wiping a trail backwards reads as undoing time. *Fits content like:* an undo in software; reversing a chemical reaction; "what if we hadn't…". - **Two pens at once.** A live duet comparing two quantities. *Fits content like:* two savings plans; two runners; a population vs its food supply. - **Ghosts of the old lesson.** A faint previous drawing becomes relevant. *Fits content like:* a theory replaced; last year's forecast; a first draft. - **The full-board view.** Every region seen at once as one picture. *Fits content like:* a system diagram; a history; a map of a field. ## 9. Pitfalls of the medium - **One pen, too many jobs** drifts later and later → give each drawing a deadline window and let overlapping jobs go to another pen. - **Minimum stroke duration × many dashes** makes a dashed line take seconds → dashes need their own floor. - **A pooled-ink dot bigger than the stroke start** leaves halos on every letter → keep it inside. - **Punctuation vanishes** (a font period is a 1 px stroke) → render sub-width strokes as dots. - **Labels half-cut by a push-in** look sloppy. - **Motion blur with few sub-frames** strobes text. - **Eraser paths** crossing labels you want to keep. - **Voice and phoneme set mismatch** (a British voice with US phonemes) mispronounces → match the language code to the voice; ASR-check. ## 10. Engine `demo/engine/wb.js`: hand-drawn shapes (`line`, `curve`, `poly`, `arc`, `circle`, `rect`, `arrow`, `dashed`, `hatch`), `text()` in writing order from a single-line font (`loadFont`), `Stroke`, floating `Pen`s, `Timeline.draw(pen, shapes, t, {by})` (solves hand speed to a deadline), `Timeline.erase`, `Timeline.cue`, keyed `Camera`, `Board` (ink multiply, dry texture, erasers, sheen, props), prop drawers. API table and a minimal example that draws something new: [DEMO.md](DEMO.md#engine-reference). ## 11. Variation space You decide the topic's object, the board layout, the colours within the logic, the voice, the music family, the camera route, the opening, the ending and the length. All far from our demo: - Structures: **a proof** (one claim at the top, the board fills downward step by step, each step boxed when proven); **a debate** (two pens, two halves of the board, each drawing its side until the drawings meet in the middle); **a timeline** (one long horizontal line ridden left to right, with events hanging off it). - Openings: **a question mark** drawn huge in the centre, then shrunk to become a dot in the first diagram; **an erased board** where the ghost of a wrong answer is still visible; **a magnet dropping** onto an empty board with a clack. - Endings: **the answer circled** twice and the pen capped; **the board wiped** except for one line that survives; **a push into the smallest symbol** on the board, which becomes the title. --- How our demo was made (story, shots, score, end card, build): [DEMO.md](DEMO.md). Read it after your treatment exists.

# Swiss Motion Graphics — Style Prompt > International Typographic Style in motion: a modular grid, one typeface, one signal colour, and movement as exact as a printing press. > References (grammar only): 1950s–70s Zurich posters (Müller-Brockmann, Hofmann, Gerstner, Crouwel) for the grid, flush-left type, scale contrast and "designing programmes"; modern identity systems in motion (Experimental Jetset, Pentagram) for snaps on the beat. Never copy a specific historical poster's composition (no concentric-circle or fan layouts lifted from Müller-Brockmann), never use Helvetica or Akzidenz font files, never name a real institution on a poster. ## 1. Essence, and what it is not - **Pure 2D graphic design animated on a grid**: flat paper, black type and bars, a very light grey and **one** saturated signal colour. - **Every element snaps to the grid, every move lands on a beat, nothing bounces.** - **Rigor with one exception**: the whole frame obeys a system, so the one element that doesn't becomes a character. - **Extreme scale contrast**: a giant numeral next to tiny technical notes. Not a keynote (no gradients, no glow, no device renders), not kinetic typography for a lyric video (words don't fly, spin or bounce), not data visualisation (bars have mass as graphic form, not as charted quantities, unless the grid gives them that meaning), not a Bauhaus pastiche of primary shapes. ## 2. Materials & rendering - **Frame grid**: 1920×1080, 12 columns, ~96 px side margins, 24 px gutters, 24 px baseline. The frame can act as a **spread**: a left page (the programme: numeral, rule text, notes) and a right page (the artifact). - **Artifact grid** derived from the content (Gerstner): what the columns and rows *mean* is a design decision. **Choose module sizes that give the elements mass**; too many thin columns make a layout look like a chart. - **Surfaces**: page, paper, ink, signal colour, grid lines in two or three light greys (on page, while building, on paper). No gradients, no shadows, no particles, no grain (mux grain 0). - **Bars and blocks** are flat rects; consecutive cells of one unit merge into one bar, overdrawn 1 px at seams (antialiasing shows hairlines, especially when rotated or scaled). - **A secondary voice** can be light-grey elements under the black ones: depth without a second colour. - **A 2D camera matrix** (centre, scale, rotation) for all moves. ## 3. Colour logic - **Paper, ink, greys, and one signal colour.** Only one thing carries the signal colour; that makes it the protagonist. It is the only thing allowed to be inexact. - Overprint is allowed: black type on the signal colour. - The signal colour can be red, orange, ultramarine or green; choose it for the topic, then never add a second. - Examples: `#EAE9E5` page, `#FFFFFF` paper, `#111111` ink, signal `#E30613`; or `#F2F0EA` / `#141414` / signal `#FF5A00`; or `#E9ECEF` / `#0B0B0B` / signal `#1F3FFF`. ## 4. Type & subtitles - **One family for the whole film**, an OFL neo-grotesque (Archivo, Inter, Schibsted Grotesk, Instrument Sans…), several weights. Letter-spacing ~−2 % at ≥ 90 px. Headlines can be lowercase. Load every weight with `document.fonts.load` before drawing. - **Flush left, ragged right**; everything on a grid line; big white space is part of the layout. Giant numerals are **optically** flush left (subtract the glyph's left bearing). - **Subtitles are part of the layout**, not a bar at the bottom: each line sits at a column start in the current composition (a small grey lead-in + a large bold statement, or a caption like a museum label), each word clip-revealed on its whisper timestamp. Hold ≥ max(1.8 s, speech + 0.6 s); assert it in code. - **Caption rows**: small (~19 px) medium-weight notes with a 1 px rule above; technical notes in a corner (module sizes, counts, a bar counter). ## 5. Motion quality - **Two curves only**: a precise ease `cubic-bezier(.7,0,.2,1)` for snaps; linear for lines being drawn, playheads and the exception. No overshoot, no spring, no bounce. - **Durations are note values** at the film's tempo. A snap starts one note value early and **lands on the beat**. - **Entrances are wipes or clip-reveals, never fades**: words rise out of a clip rect from below the baseline and leave upward; lines grow along their length; paper appears by a wipe; big numerals climb in eased steps ("one module at a time"). - **Deletions are knife cuts**: a thin line crosses the element, then the element collapses to its midline. - **Ripples are ordered by distance** from their cause, a couple of units per subdivision. - **The exception moves differently**: linear, unsnapped, perhaps pausing mid-flight; a coordinate readout beside it can turn from "on grid" to "off grid". - Smooth 24 fps, no stepping: digital precision, not hand-made. ## 6. Camera grammar A vocabulary, not a route. The camera moves only with the precise ease and only on beats. Opening and ending come from the topic. | Move | What it expresses | Can serve | |---|---|---| | Locked spread | cause (left) → effect (right) | a rule applied; a before/after; a comparison | | Hard pan by one page or column | the next step in a system | a sequence; a catalogue; a timeline | | Rotate 90° and stop | the same thing read another way | a poster as a score; a chart as a map | | Pull out to a wall of artifacts | one programme, many outputs | a brand system; a product range; a series | | Push into one module | detail; the unit of the system | a pixel; a letter; a single data point | | Grid extends past the page | the system is bigger than the artifact | scale; ambition; a break from constraints | | Split frame into equal cells | parallel cases | options; variants; team members | | Vertical scroll through a column | reading; a list | a manifesto; a spec sheet; a timetable | Framing: everything on the grid; the signal element may sit off-grid only when it is being the exception. Transitions are wipes, knife cuts, camera moves and re-flows; never dissolves. ## 7. Sound palette - **Music with a grid of its own**: a steady pulse whose subdivisions give snap durations. Options: motorik / krautrock kit and bass, minimal techno, marimba or vibraphone patterns, a mechanical piano ostinato, a drum machine with a glockenspiel; one instrument added per new rule is a clear build. - **Picture and music can share one data file** (a column → pitch, a row → onset), so a graphic can literally be the score. - **Techniques (options)**: drop the drums for the one moment of the exception; a near-silent bar before a reveal; thin the band during a reveal so every note is audible. - **Foley follows the materials of print**, dry and close, no reverb: letterpress clack, ruling pen "tss", guillotine snick, paper slap and slide, numeral thunk, block snap, felt thump for a landing, rubber stamp, typewriter carriage. - **The exception can be the only element that sings** (a sine glide following its position). - **Silence**: a hard stop of everything on a downbeat; the next snap reads as an event. - **Mix**: voice compressed and ≥ 6 dB above music, music ducked ~10 dB under voice, −14 LUFS. - **Voice**: cool, crisp, rule-like sentences; prefer voices with bright consonants. ## 8. Native moves A menu: use the ones your story needs. - **The grid means something.** Columns and rows become a quantity (notes, hours, floors, years). *Fits content like:* a building's floors and rooms; a week's timetable; a city's districts. - **Snap = beat.** Every arrival is a percussion hit. *Fits content like:* a product's feature list; the steps of a recipe; a countdown. - **Programme.** Rules applied one by one to one artifact, then the same programme generating many. *Fits content like:* a brand identity; a typeface family; a set of stamps. - **Extreme scale contrast.** A giant element as chapter card beside tiny notes. *Fits content like:* a record statistic; a year; a price. - **The exception.** One element breaks the grid, linear and unsnapped. *Fits content like:* an inventor; an outlier in the data; a rebel employee. - **Knife cut.** An element deleted by a line. *Fits content like:* budget cuts; editing a text; removing a feature. - **Re-flow.** Everything else rearranges around a change, nearest first. *Fits content like:* a team reorganised; traffic after a road closes; a layout adapting to a phone. ## 9. Pitfalls of the medium - Too many thin columns look like a chart → fewer, wider modules. - A "better" composition that isn't obviously better → one strong diagonal with long/short rhythm, a larger signal element, bleeds, type over colour. Merely tilting is not enough. - Rotating and labelling at once reads as noise → rotate, hold, then add labels. - Merged bars show seams after rotation → overdraw 1 px. - Elements that share the camera matrix leak into other shots → draw them only when on screen. - Canvas `letterSpacing` affects `measureText` → measure after setting the font. - Onsets that fall between frames flicker → put visual onsets on whole frames. - Whisper splits or merges words and pads the first word → align by letters, clamp to 0. ## 10. Engine In `demo/`: `ease.js` (`cubic-bezier(.7,0,.2,1)`, `snap(t, t_arrive, dur)`, `steps()`, `track()`), `film.js` (layout system, clip-reveal text, knife cuts, bars from a score, rotation reveal, wall of artifacts, caption rows), `main.js` (fonts, whisper word times, `?nosub=1`, `?poster=1`), `score.json` (the shared data file for picture and music), `tools/words.py` and `tools/subs.py` (word timings, asserted subtitle intervals). File list and build steps: [DEMO.md](DEMO.md) "Build notes". ## 11. Variation space You decide the system, what the grid means, the exception (or none), the signal colour, the opening and the ending. All far from our demo: - Structures: **a timetable** (a 24-row grid of hours fills with the topic's day, one row per beat); **an alphabet** (A to Z, each letter a module of the topic, the grid completing as a specimen sheet); **a comparison** (two systems side by side on a split spread until one element crosses the gutter). - Openings: **a single dot** placed on the page, then the grid growing from it; **the finished artifact** that is then dismantled into its rules; **a giant numeral** filling the frame, which turns out to be a detail of a small layout. - Endings: **the empty grid** after every element has been cut away; **a single word** flush left in the corner; **the exception leaves the frame** and the system closes over the space it left. --- How our demo was made (story, shots, score, end card, build): [DEMO.md](DEMO.md). Read it after your treatment exists.