Colored-Pencil Science Illustration — Style Prompt

A real 3D cutaway world (ground, soil horizons, stones, buried structures, living things) redrawn every frame as a colored-pencil plate on toothed paper: four layers of pencil, a wobbling graphite contour, labels pencilled on cream paper tags. The camera can sink below the ground, and the drawing can be drawn in while you watch: horizons coloured in stroke by stroke, growing things drawn out from their base, fine lines spreading white over dark soil. References (grammar only): natural-history picture books and textbook cutaways (soil profiles, root systems, burrows), colored-pencil illustration on cold-press paper, the multiplane camera of hand-drawn animation. Copy none of their plates, characters, layouts or typefaces.

1. Essence, and what it is not

• The whole frame is one pencil drawing. Sky, ground, soil, what lives in it and type are all pencil on the same paper; there is no "3D scene with a drawing in it". The sky is a loose blue wash with the clouds left as paper.
• The cutaway is the signature composition. Above the ground line, landscape; below it, the cut face of the soil, where the hidden things live (stones, burrows, seeds, pipes).
• It is a real 3D world. The camera can crane, push and truck through it, and things at different depths move at different speeds (multiplane parallax: the cut face slides over the far landscape).
• Drawing is an event. Every surface has a moment it is drawn; after that its four pencil layers arrive one after another, stroke by stroke.
• Restraint. One idea per shot, one visual focus, few labels. A science plate earns its clarity by leaving things out.

Not Watercolor (no washes, blooms or wet edges: every tone is built from strokes), not Urban Sketch (no ink line plus wash; the line is graphite and coloured pencil), not Crayon Picture Book (fine, controlled hatching, not waxy scribbles), not Isometric People Scene (perspective camera, a real cut face, depth).

2. Materials & rendering

• Paper: warm off-white with a tooth (fine grain, laid fibres, soft cockling). Pencil only lands on the raised tooth, which is where the colored-pencil grain comes from. The base mottling of blank paper is fixed to the screen.
• Four pencil layers, in this order, over every surface:
• L0, side of the lead: a soft broad fill in the local colour, tooth-limited.
• L1, local colour hatching: patches of short parallel strokes, each patch slightly re-angled; strokes follow the object (along stems, cables, trunks and blades; around stones and leaf clumps; a fixed diagonal for soil).
• L2, cool cross-hatching: in the shadows only, a darker and cooler version of the local colour, at another angle.
• L3, accents: deepest darks in sepia or indigo, a third angle.
• Contour: a graphite line from breaks in object id, depth and normal; the nearer surface owns the line; distant lines fade (aerial perspective).
• Labels: cream paper tags with a pencilled edge; the writing is graphite, written along the glyph skeletons stroke by stroke (never wiped on). Overlay marks share the paper tooth.
• Pipeline (reference): three.js renders G-buffers (albedo + id, light + depth + normal, hatch direction, anchor coordinates + reveal time) at 2× and a post shader redraws them as pencil, then a 2× box downsample. See demo/main.js.

3. Colour logic

• Warm, restrained, paper-led. Bedrock is blue-grey, never large areas of black.
• Accents carry meaning, at most three in a film, each always meaning the same thing (say amber for warmth, cobalt for groundwater, red for one burrowing animal).
• White pencil over dark is how fine lines, highlights and anything delicate read on soil.

4. Type & subtitles

• One OFL handwriting face with a pencil feel (the demo uses LXGW WenKai, whose Latin comes from Klee One). English leads; one short Chinese line may follow.
• Labels in capitals on paper tags, at most one per shot; the Chinese at about 1.05× the English size, slightly lighter. A short pencil leader with a pale paper halo under it so it never reads as another line of the drawing.
• Titles are written in pencil on the sky, stroke by stroke, with a hand-drawn underline.
• Subtitles (when spoken): a cream paper slip, bottom left; Chinese over English, each one line; wiped on quickly (they are read, not drawn). Keep the subject out of that corner.

5. Motion quality

• Strokes stick to what they draw. Hatching, the tooth inside the pigment and the contour wobble are computed in anchor coordinates: each surface point projected through a fixed reference camera. Inside a shot group the camera only translates (crane, truck, push), so the anchor is exact and nothing swims under a fixed pattern.
• Only the contour boils: a new drawing every 2 frames, 3 drawings cycled, about 1 px. Hatching and colour fields do not boil.
• Things that move do so on twos (12 drawings a second: grass in the wind); the camera moves on ones.
• Drawn in, not faded in: a sweep colours a horizon left to right with a ragged front; growing things (stems, vines, cables) appear from their base outward, already carrying their base colour, and finish their hatching within a few frames; tips grow pointed.
• Particles (grains carried along a structure) are small 3D objects drawn by the same pencil, never glowing dots.

6. Camera grammar

• Sink: a vertical crane from the landscape into the cut face; the soil rises over the far view.
• The magnifier: a pencil circle drawn around a detail; inside it, the magnified view is drawn from blank paper outward from the centre; the circle grows to fill the frame. The reverse (the circle shrinking to a point in a wider view, then erased) returns. This is how the style changes scale, and it re-anchors the strokes at the new scale.
• Focus is how fully something is drawn. No optical blur: the subject gets all four layers and a firm line; what is behind keeps one light wash and a faint line. A focus pull moves "fully drawn" from one thing to another.
• Inside the magnifier, draw only what the shot is about; illustrators leave things out.
• Follow: a truck alongside a moving particle, which sits left of centre with space ahead.
• The orientation stays fixed inside a shot group; to turn, change scale or cut through a magnifier.

7. Sound palette

• Pencil foley driven by what is being drawn: graphite writing (high, fine), waxy colour pencil hatching back and forth (lower, panned with the sweep), long soft strokes for long growing forms, a dry crackle for spreading fine lines, a light tap for a paper tag, a wooden "tock" for the magnifier.
• Ambience follows the camera: wind and distant birds above ground, closed down by a low-pass as the camera sinks, a quiet low earth tone below.
• Score in acoustic, intimate colours (nylon guitar, flute, clarinet, pizzicato bass, harp, bowed vibraphone, marimba and kalimba); leave 400 Hz–2.5 kHz light for a narrator.

8. Native moves

1. The blank half: a finished landscape whose underground is still blank paper, waiting to be drawn.
2. The horizon sweep: soil coloured in left to right as the camera sinks, the four layers arriving in order.
3. Growth drawn outward from its base, tips first.
4. White over dark: fine lines spreading across soil in white pencil, bridging structures.
5. The magnifier in and out (a pencilled circle as a transition and a change of scale).
6. Focus by drawing: wash ↔ fully drawn.
7. A grain on a thread: a coloured particle travelling along a structure, the camera following.
8. The plate: the final wide cutaway, everything drawn, the title pencilled in the sky.

Our demo opens on the blank half and the sink below the horizon, uses the magnifier (in, then out again) as its turn and ends on the plate. A new film opens and ends another way: already inside the magnifier, pulling back out to the landscape; a grain on a thread followed from the first frame; nested magnifiers down to a microscope inset; or an ending held close on one detail as focus by drawing passes to it.

9. Pitfalls of the medium

• Hatching fixed to the screen while things slide under it ("through glass"), or re-randomised every frame (the whole screen flickers).
• Rotating the camera inside a shot group: the anchored strokes stretch. Turn by changing scale or cutting.
• Square noise cells as soil grit; grains must be round.
• Blank paper left "waiting" for more than about a second, with no drawing front moving: it reads as a bug.
• Growing tips that start as white sticks on dark soil: grow them already coloured.
• Too many labels, rulers and arrows: the plate turns into a worksheet. One label per shot.
• 3D-render tells: translucency, glow, bloom, depth-of-field blur, drop shadows on type.
• Lines thinner than about 1.5 px in a wide shot shimmer: thicken them for wide views, keep the finest for close-ups.

10. Engine

• three.js (from the library's node_modules), one scene, a perspective camera with fixed orientation; four G-buffer passes at 2×, one pencil post pass per view, a composite pass (magnifier, overlays), a 2× downsample.
• Reveal: a per-vertex time (arev) or a per-material sweep; the post pass gates each of the four layers by time since reveal, with every stroke given its own turn.
• Overlays: 2D canvases for paper (tags, slips), graphite (writing, lines) and coloured pencil (dashed paths), composited with the same tooth.
• render(t) depends on t only; about 60–130 ms a frame at 1080p on Apple silicon.

11. Variation space

• Subjects: any cutaway or cross-section: soil horizons, burrows, caves and aquifers, riverbeds, seeds germinating, a stem or organ in section, pipes and foundations under a street.
• Paper: warm white, cream, a cool grey; tooth coarse or fine.
• Palette: autumn (oranges in the foliage), winter (bare branches, frozen topsoil), night (indigo sky pencil, the same paper).
• Scale journeys: landscape → plate → microscope inset → back, nested magnifiers.
• Labels: picture-book handwriting, or neat small capitals for a museum tone.

How our demo was made (story, shots, score, end card, build): DEMO.md. Read it after your treatment exists.