Style Engraving

---
name: style-engraving
description: Engraving style (in testing): 3D scenes drawn as a plate of the «Description de l'Égypte» — charcoal tone on toothed paper, masonry drawn stone by stone, temple walls in low relief (registers of offering scenes, Hathor capitals, starred ceilings), an aged print measured on the originals, one live blue and a gold wash as second inks. Instanced WebGL, so thousands of pieces are cheap. Use it for architecture, archaeology, temples, machines, exploded views, scientific plates, or when working with styles/engraving/.
---

# Style · Engraving

Reference in testing: `sandbox/2026-09-26-pyramid-engraving/` («The pyramid that makes skies»,
63.6 s, ten shots from the desert to a sky inside a seed). References the user chose: the
plates of the «Description de l'Égypte»: Vol. V (Giza, Pl. 9, 11, 13, 14) for the outside,
Vol. IV (Dendera, Pl. 17, 25, 30) for walls, friezes and interiors (Wikimedia Commons, NYPL).

## Code

`styles/engraving/engrave.js` → global `Engrave`.

- `Engrave.renderer(env, { scale })` → `R.mesh(name, geom)`, `R.render(g, key, frame)`.
  Built-in meshes: `box`, `pyramid`, `cylinder`, `sphere`; `Engrave.torus(r)` for rings.
- Instances: `Engrave.inst(arr, centre, material, half, seed, quat, glow, bias)` (16 floats).
  Materials: 0 limestone, 1 worn limestone, 2 obsidian, 3 gold, 4 live blue (emissive),
  5 sand (a flat `box` instance with `N.y` up is the desert: dunes bend its lines), 6 bronze.
- A draw: `{ mesh, inst: Float32Array, box: true }` (box = cut edges, pores, chips) or
  `tan: 'y'` for a round mesh hatched along its axis (cylinders; rings default to round it).
  `cast: false` for things that must not shadow (glow lines, dust).
- Frame: `cam, target, fov, sun, sunK, fill, lights: [[x,y,z,0,strength]]` (second-ink
  lights), `shadow: { center, radius }` (make the radius follow the subject: small in a
  close-up, or the shadows go blocky), `sky: { zenith, horizon }`, `fog`, `spacing` (px at
  1920), `frame` (the plate's image area; outside it, bare paper).
- The plate (margins, neat line, running heads, caption) is 2D on top, in IM Fell DW Pica SC
  (`fonts/IMFellDWPicaSC-Regular.ttf`, OFL). See the scene's `film.js`.

## The approved look (drawn in charcoal, on old paper)

Round 6 of the pyramid film moved the look from «a render with a charcoal filter» to «a
charcoal drawing»: `hatch: 1` and `contour: 1` in the frame. The tone is laid with the side
of the stick (`pencilAt()` → broad soft strokes, `stickAt()`, on the paper's tooth); the
contours are drawn by the ink pass over geometry buffers (`INK_FS`: silhouettes, folds and
the carving's edges as a broad, soft, wandering line); the colour is old yellowed paper
(`AGE_GRAD`: the gold rings' tan in the light mid-tones, sepia darks). Thin pencil hatching
was tried and rejected («te has pasado de lápiz… la idea es que fuera carboncillo»). The
paragraphs below describe the earlier stage, still true where they don't contradict this.

## The earlier look (charcoal on the surfaces + the plates' colour)

The user approved («¡Lo has clavado!») the **charcoal** mode over the ruled burin lines:
`charcoal: true` in the frame (and `grain`: 1 outside, 0.45 indoors) and
`Engrave.ager(env).apply(g, R.layer(key, f), { ink, paper })` to paint. Then, seeing it
move: «el filtro lo quitaría, creía que se vería a nivel de texturas y no de pantalla»:
**nothing is fixed to the screen**. The paper's tooth and the strokes are a texture of each
surface (`charcoalAt()` in the scene shader: triplanar in the piece's own space, two
octaves cross-faded so the grain keeps its size on screen), the sky's in its directions;
the ager only downsamples and maps colour. What makes it:

- stone faces drawn as a **mosaic of small hand-cut stones** in courses (`course`, world
  size of a course): joints as broken pencil marks on the lit side, dark stones with lighter
  joints in shade; the mosaic stays on up close (a big stone is still a drawn wall);
- tone laid as **graphite in short diagonal strokes** that catch on the paper's tooth only in
  the half-tones (lights stay clean, darks fill in), stuck to the surface it shades; drawn
  marks stay crisp;
- the **plates' colour**: tone curve and gradient map measured on the plates (a greyish warm
  paper, a warm black), second inks carried over. No grain, toning, rim or smudge on the
  frame: those read as a dirty lens once the camera moves. The sheet's toning and foxing
  live on the printed plate's margins (`print()`), which grow with the plate (`sheet`);
- light as in plate 11: sun from the front left (`sun: [-0.35, 0.5, 0.8]`, `sunK: 0.8`,
  `fill: 0.2`), a light rubbed sky (`zenith 0.22, horizon 0.15`).

Calibrate against the plate with `sandbox/2026-09-26-pyramid-engraving/plate-test.js`
(one smooth pyramid from afar) before touching a scene.

## Interiors (the temple)

Draw flag and frame field for a room inside: `interior: true` in the frame. Then:

- **Walls are one dressed surface, not stones, and no stone is left empty** (worked on a
  corner bench, `bench.js`, beside a crop of Dendera at the same size). A tall box
  (`vH.y > 0.6`) or a column (`cylinder` with `tan: 'y'`) inside is decorated by
  `templeWall()`: a dado of lotus stems; three registers, each a row of panels (a king
  offering at an altar to two or three gods, standing or enthroned) whose figures fill the
  register's height; columns of signs between ruled verticals fill every gap; a frieze of
  text and uprights, a torus bound with a spiral band, a fluted cornice. Columns are stacks
  of thin bands of signs, cartouches and uprights over one scene register.
- **Relief is the wall's own tone,** a shade lighter, drawn by its bevel (the edge towards
  the light pale, the far edge dark), a fine contour and inner lines. White cut-out figures
  read as stickers.
- **Figures follow the canon** (`sdStanding`, `sdGoddess`, `sdSeated`): profile head with
  wig, frontal shoulders, narrow waist, legs with knee and calf, long feet in a stride,
  arms with elbows and hands; kilt and apron, or the sheath dress; crowns (`crown()`).
  Inner lines (`figureInner`, `seatedInner`) are masked to each figure's own body.
- **Signs are invented** (`glyphSign`, 16 of them), combined in pairs per cell so they do not
  repeat. Never real hieroglyphs.
- **Capitals:** a box draw with `hathor: true` carries, on each side, the creature (the
  user's choice, in the place of Hathor's face) in relief in a sunk ruled niche, framed by
  the shrine with its winged disc and uraei, the wig band, banded lappets ending in curls,
  the bead collar; text in the corners; no masonry courses. The flared `capital` below
  takes `hathor: true` too: two rows of ribbed lotus petals.
- **Ceilings** (`templeCeiling`): bands between beams, one subject each: vultures with
  spread wings, stars on a sunk field, boats of the hours; text along the edges, signs on
  the beams.
- **Floors**: large flagstones in rows (frame field `flag` sets their width per room), each
  its own slight tone, worn lighter where walked, broken joints that still read in shade,
  sand beside them and in drifts, cracks, chipped corners, pits, pebbles with a shadow;
  loose stones (`rock`, drawn in flat facets with their arrises) and furniture from
  `props.js`.
- **Metal is engraved:** rings as an armillary's (rules, a graduated scale on one face,
  signs on the other; slim tubes bands every 10°), rods with collars and spiral fluting.
- **Anything built is carried:** walkways and slabs run into walls and sit on stepped
  corbels or struts; nothing hangs in the air unless the story says so.
- The paper's tooth is finer indoors (`grain: 0.45` in the ager), or the carving drowns.
- Light comes in as the story needs (slits with dust motes in the beams: bias −1 prints a
  mote as bare paper; a shaft lit from above); `fill ≈ 0.4` so shade stays drawn.

A night sky (inside the seed): `sky` above 1 (a dark rubbed ground), stars as `sphere`
instances with bias −1 (bare paper), sizes small and many (thousands), an engraved star as
four long and four short thin rays.

## Rooms joined by doorways (portals)

A film through many rooms, each built in its own coordinates, scale and light, still plays
as one camera move: every change of room is an **opening** (a ring, a tunnel's end, a door,
a sphere's skin, a shaft) through which the next room is already seen, and the camera flies
through it. `Engrave.portal(a, b)` maps one room onto the next through the opening's frame
in each (`{ c, q, s }`, +z the way through; `Engrave.frameQ(fwd, up)` builds `q`); draw the
opening as material 7 (a hole with depth), render the far room from the mapped camera with
`f.clip` = the portal's plane, and lay it under the near layer; with two openings in view,
cut each far room to its own hole (`R.mask(f, hole, others)`). The scene's `junctions.js`
has the rest: bridging the camera across (a Hermite through the opening, speeds matched and
capped so a change of scale never overshoots) and what leads through first.

- The opening's `up` can differ between rooms: the room beyond comes turned (a floor ring
  whose room is a vertical shaft; a tunnel into a hall whose «down» is the camera's rolled
  up). That is the transition: gravity turns as you go through.
- Match sizes: whatever goes through (a structure, a seed) keeps its size, so the two
  openings' scale is its scale.
- Keep the opening live whenever it can be seen, or it pops from wall to view.
- Nothing flies through a solid: part a skin (an iris of leaves) where the camera goes in.

## Style rules

- **Tone is graphite on toothed paper,** never a flat grey: laid in short diagonal strokes,
  catching on the tooth only in the half-tones. Drawn marks (joints, relief edges, signs)
  stay crisp lines.
- **Outside, stone is a mosaic of small hand-cut stones** in courses; up close (a course
  over ~22–70 px) the limestone takes over: vugs with a lit lip, pits, coin fossils, cracks,
  broken arrises, sand in the joints, a mottle; no wavy dashes. Inside, walls are dressed and decorated (above).
- **Textures belong to the piece** (`vQ`, the piece's own space): they never swim when the
  piece or the camera moves. Round pieces measure arc length, not a dot product. That goes
  for the paper too: no screen-space grain, stroke, vignette or toning over the image.
- **Colour is a second ink:** live blue on what is alive (channels, marks, the seed), gold as
  a wash on metal; three quarters of the frame stay ink on paper.
- **The ground is drawn:** dunes everywhere with lee slopes in shade, patchy wind ripples
  (dark lee strokes), mottling, pebbles; no flat patch next to a busy one.
- Dust, pores, pebbles and stars are stipple; motes in light are bare paper. A grain never
  grows past ~16 px on screen (the vertex shader clamps it), or it passes the lens as a disc.
- Nothing crosses stone: rings are sized to the room they turn in, slabs keep their gaps.

## Style checklist

- [ ] Side by side with the plate at the same size: tones measured, not guessed.
- [ ] No flat grey at full size (walls in light, shaded faces, metal, sand).
- [ ] Walls inside: registers readable but not shouting; no two neighbouring panels alike.
- [ ] Every room furnished and dirty (tables, jars, statues, rubble, dust at the walls).
- [ ] Nothing in the foreground covering half the frame by accident (rings, mounds, blocks).
- [ ] Blue only on what is alive; gold only on metal.
- [ ] Every element cropped at full size: no blank stone, ceiling, floor, capital or metal.
- [ ] Two frames 1 s apart with the camera moving: the grain moves with the stone, nothing
      stays put on the screen.
- [ ] Every change of room goes through an opening in the shot (a portal, below), never a
      cut or a fade to dark.
- [ ] Nothing built floating: every slab, walkway, beam has its bearing.

## Lessons

- 2026-09-26 · pyramid-engraving · A line thinner than a pixel must print lighter (scale its
  coverage by width/AA), or every faded line becomes a half-tone smear and level changes
  show as diagonal bands of moiré.
- 2026-09-26 · pyramid-engraving · An exploded building reads when each face moves out along
  its own normal (the corners open into V gaps that show the inside); scaling the shells
  about the axis only makes a lattice that hides the heart.
- 2026-09-26 · pyramid-engraving · «It still doesn't look like it» three times: parallel burin
  hatching read as 3D with a filter. What the plates actually do was only seen by cropping
  the plate next to our render at the same size and measuring tones: faces are mosaics of
  tiny drawn stones and soft, grainy tone. Put the reference beside the render first.
- 2026-09-26 · pyramid-engraving · A ruling measured as dot(position, direction) races on a
  curved piece when the direction turns (rings, cylinders): measure arc length instead, and
  never add a per-piece offset to the position (it multiplies the error).
- 2026-09-26 · pyramid-engraving · The colour of «old» is measured, not guessed: a gradient
  map from the plates' own pixels (their paper is greyish, not cream) did more than any
  sepia tint.
- 2026-09-26 · pyramid-engraving · «The walls don't look Egyptian»: the fix came from the
  plates themselves (Dendera): smooth dressed walls filled edge to edge with registers, not
  stones with a few signs. Download the references first and copy their structure.
- 2026-09-26 · pyramid-engraving · «The glyphs repeat»: one sign per cell from a fixed grid
  repeats visibly; vary the panel widths, the composition per panel, pair signs per cell and
  offset each wall.
- 2026-09-26 · pyramid-engraving · A low camera on a lit foreground mound flattens the whole
  frame; look over the dunes so their lit and shaded sides read.
- 2026-09-27 · pyramid-engraving · «Trabaja más en detalle y zonas más pequeñas»: one bench
  scene (a corner with wall, column, capital, ceiling, floor) with a view per element, each
  compared at full size with the plate, moved the rooms further in a night than the film
  shots had in days. Give every bench view its own layer key: the renderer memoises the
  layer by key and silently returns the first view.
- 2026-09-27 · pyramid-engraving · The figures stayed «schematic» until they were rebuilt
  from the canon (tapered limbs with knee, calf, ankle; frontal shoulders; profile head),
  not by adding lines to stick figures.
- 2026-09-27 · pyramid-engraving · A texture laid in screen space after the render (grain,
  strokes, toning, vignette) passed every still and failed the first moving render: judge
  the look on a render with the camera moving, and put every mark on a surface.
- 2026-09-27 · pyramid-engraving · Taking the screen grain away uncovered what it had hidden:
  square cells printed as flecks (make every stipple a round, jittered dot), a noise that
  jumped at its lattice lines on the NVIDIA card (value noise hashes its lattice in integers,
  `precision highp int`), creases in the ground (a footprint from `max(|x|, |z|)` folds along
  the diagonals; use a rounded square) and a grain scale from derivatives that stepped at
  every triangle (take it from the distance). After removing a full-frame filter, crop the
  ground, the sky and a floor at full size again.
- 2026-09-27 · pyramid-engraving · «Que parezca dibujado» is charcoal, not pencil: thin
  hatching lines everywhere read as an engraving or a comic. Charcoal is a broad soft tone
  with the paper's tooth showing through, strokes of the stick's side that modulate it, and
  broad soft contours; show one still per step (colour, then contours, then tone) and let
  the user steer before a full render.
- 2026-09-27 · pyramid-engraving · A mark that «appears» should be painted: one line traced
  at an even pace with a bright point at its tip reads as drawn; a fast ramp of the whole
  figure (0.8 s for 28 segments) reads as popping in.
- 2026-09-27 · pyramid-engraving · Cuts through a fade to dark between rooms read as jumps
  («creía que serían transiciones naturales»); rooms joined by portals through something in
  the shot, with the camera's speed matched across, play as one continuous travel.