CRT
64e8932d1b
The page block was written as 1.035 of the cover, spilling past it on three sides -- the comment above it said so plainly, and it is backwards. The overhang is called the square and it is the entire point of a board binding: the boards take the knocks so the leaves do not. Written the wrong way round the model read as a ream of paper with a leather lid, which is what it had always looked like. Flush at the spine, inset on the three free edges, and the leather now shows around the block. With that, the boards are also thicker. At a ninth of the book each they came to 14 mm against 48 mm of paper; a medieval binding is oak boards first and leather second, and they are substantial. And the book now has its corner bosses. They are the most recognisable thing about a book of this period and there were none. Not ornament either: a volume this heavy was stored flat, often on its side, and the bosses hold the leather clear of the shelf so it does not abrade -- the same edges the square protects. The pouch's body goes from nine sides to thirteen. Leather has no facets, and the body is the whole silhouette of that model. The spilled coins beside it stay. That is not a fault: the config field says "number of coins spilled outside", so the scatter is the model's own idea and pulling it in would be redesigning rather than fixing. 27 models, 19007 triangles, all checks pass, 0 floating cases, build clean.
207 lines
8.1 KiB
TypeScript
207 lines
8.1 KiB
TypeScript
/**
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* @medieval-kit/leather-book
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*
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* Leather-bound manuscript with a clasp. Table, shelf, inside a chest, lectern.
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*
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* The whole point of the model is the PAGE BLOCK. What makes a book a book is
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* not its cover but the uneven mass of paper spilling past that cover. Give it
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* as a flat box and it reads like a brick no matter how good the cover is.
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*
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* Two period details drove the geometry:
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*
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* - The pages are NOT PAPER but vellum (parchment), i.e. animal skin. That
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* makes them thick, yellowed and wavy. `roughenGeometry` puts that
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* waviness on the edge of the block.
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* - The book DOES NOT stay shut: vellum draws in moisture and swells. That
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* is why real manuscripts have a clasp — function, not ornament. Without
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* the clasp the model loses its period.
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*/
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import type { BufferGeometry } from 'three'
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import {
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boxGeometry,
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chamferedBoxGeometry,
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createKitModel,
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createTinter,
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jitter,
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mergeColoured,
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flipGeometry,
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prismGeometry,
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roughenGeometry,
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} from '../core/index.ts'
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export interface LeatherBookConfig {
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/** Cover width (metres). */
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readonly width: number
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/** Cover length (metres). */
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readonly length: number
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/** Total thickness of the closed book (metres). */
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readonly thickness: number
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/** Number of raised bands on the spine. */
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readonly bands: number
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/** Number of clasps. */
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readonly clasps: number
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readonly seed: number
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}
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export const leatherBookDefaults: LeatherBookConfig = {
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width: 0.19,
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length: 0.27,
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thickness: 0.062,
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bands: 3,
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clasps: 1,
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seed: 79,
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}
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export type LeatherBookParts = 'cover' | 'pages' | 'clasps'
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export function createModel(overrides: Partial<LeatherBookConfig> = {}) {
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return createKitModel<LeatherBookConfig, 'leather' | 'cloth' | 'brass', LeatherBookParts>({
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id: 'leather-book',
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defaults: leatherBookDefaults,
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slots: ['leather', 'cloth', 'brass'],
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build: ({ config, random }) => {
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const tint = createTinter(random)
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const half = config.thickness / 2
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// 0.16, not 0.11. At a ninth of the book each way the two boards came
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// to 14 mm against 48 mm of paper, and the thing read as a ream with
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// leather stuck to it. A medieval binding is oak boards first, covered
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// in leather second, and they are substantial.
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const boardThickness = config.thickness * 0.16
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const halfWidth = config.width / 2
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const spineX = -halfWidth
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// --- Covers ------------------------------------------------------------
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// Not just two boards: the spine is the single piece of leather wrapping
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// them. So the spine is NOT coplanar with the side faces of the boards,
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// it overshoots them slightly — both real bookbinding and coplanar-face
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// avoidance.
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const cover: BufferGeometry[] = []
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for (const side of [-1, 1]) {
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cover.push(chamferedBoxGeometry(
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[config.width, config.length],
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[config.width * 0.995, config.length * 0.997],
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boardThickness,
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config.thickness * 0.035,
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[0, side * (half - boardThickness / 2), 0],
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tint('leather', side > 0 ? 0.03 : -0.03, 0.9),
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))
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}
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// Spine: the leather wrapping the boards, curved outwards.
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const spine = chamferedBoxGeometry(
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[config.thickness * 1.06, config.length * 1.01],
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[config.thickness * 1.06, config.length * 1.01],
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config.width * 0.1,
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config.thickness * 0.05,
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[0, 0, 0],
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tint('leather', -0.06, 0.9),
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)
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// Built as an upright box and laid down: ORDER matters, rotate at the
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// origin, then translate.
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spine.rotateZ(Math.PI / 2)
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spine.translate(spineX + config.width * 0.03, 0, 0)
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cover.push(spine)
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// Spine bands: the ridges raised by the cords sitting under the binding
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// stitch. The most readable sign separating manuscript from printed book.
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const bandCount = Math.max(0, Math.round(config.bands))
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for (let i = 0; i < bandCount; i += 1) {
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const t = (i + 1) / (bandCount + 1)
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const band = boxGeometry(
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[config.width * 0.09, config.thickness * 1.12, config.length * 0.055],
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[spineX + config.width * 0.03, 0, (t - 0.5) * config.length * 0.86],
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tint('leather', 0.06, 0.9),
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)
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cover.push(band)
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}
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// --- Page block ---------------------------------------------------------
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// The BOARDS overhang the pages, not the other way round.
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//
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// This was written the wrong way round -- pages at 1.035 of the cover,
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// spilling past it on three sides -- and it is why the model read as a
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// ream of paper with a leather lid rather than as a book. The overhang
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// is called the square and it is the whole point of a board binding:
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// the boards take the knocks so the leaves do not, which is also what
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// the corner bosses are protecting. Flush at the spine, inset on the
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// three free edges.
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const square = config.width * 0.055
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const pages = chamferedBoxGeometry(
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[config.width - square, config.length - square * 1.1],
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[config.width - square * 1.15, config.length - square * 1.25],
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config.thickness - boardThickness * 2.4,
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config.thickness * 0.02,
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[-square / 2, 0, 0],
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tint('cloth', 0.09, 0.7),
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)
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// Vellum is not flat: the waviness at the edge is what makes the block
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// read as a stack of leaves.
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roughenGeometry(pages, config.thickness * 0.035, { salt: 31, scaleY: 0.35 })
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// --- Clasps ---------------------------------------------------------------
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const claspCount = Math.max(0, Math.round(config.clasps))
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const claspPieces: BufferGeometry[] = []
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for (let i = 0; i < claspCount; i += 1) {
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const t = claspCount === 1 ? 0.5 : 0.25 + (i / (claspCount - 1)) * 0.5
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const z = (t - 0.5) * config.length * 0.62
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// A strap that curls from the front face round to the back: built from
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// three pieces, because a single box cannot wrap the book's edge.
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claspPieces.push(boxGeometry(
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[config.width * 0.2, config.thickness * 0.035, config.length * 0.075],
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[halfWidth * 0.86, half - boardThickness * 0.35, z + jitter(random, 0.002)],
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tint('brass', 0.04, 0.5),
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))
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claspPieces.push(boxGeometry(
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[config.width * 0.045, config.thickness * 0.9, config.length * 0.07],
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[halfWidth * 1.012, 0, z],
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tint('brass', -0.02, 0.5),
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))
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claspPieces.push(boxGeometry(
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[config.width * 0.12, config.thickness * 0.035, config.length * 0.07],
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[halfWidth * 0.92, -half + boardThickness * 0.35, z],
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tint('brass', 0.07, 0.5),
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))
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}
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// --- Corner bosses ------------------------------------------------------
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// Brass studs at the four corners of both boards.
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//
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// These are the single most recognisable thing about a medieval book and
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// the model had none. They are not ornament: a book of this weight was
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// stored FLAT, often on its side, and the bosses hold the leather clear
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// of the shelf so it does not abrade. Without them the silhouette is a
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// modern hardback.
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const bossRadius = config.width * 0.055
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for (const side of [-1, 1]) {
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for (const sx of [-1, 1]) {
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for (const sz of [-1, 1]) {
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const boss = prismGeometry(
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bossRadius,
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bossRadius * 0.55,
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config.thickness * 0.2,
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6,
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[
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sx * halfWidth * 0.78,
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side * (half + config.thickness * 0.04),
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sz * (config.length / 2) * 0.84,
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],
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tint('brass', side > 0 ? 0.04 : -0.02, 0.6),
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)
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// Domes point away from the book on each face.
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if (side < 0) flipGeometry(boss)
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claspPieces.push(boss)
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}
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}
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}
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return {
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cover: { slot: 'leather' as const, geometry: mergeColoured(cover) },
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pages: { slot: 'cloth' as const, geometry: mergeColoured([pages]) },
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clasps: claspPieces.length > 0
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? { slot: 'brass' as const, geometry: mergeColoured(claspPieces) }
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: undefined,
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}
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},
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}, overrides)
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}
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