749 lines
35 KiB
TypeScript
749 lines
35 KiB
TypeScript
/**
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* @medieval-kit/post-mill
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*
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* A post mill: the medieval windmill, and the largest thing in this kit.
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*
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* The name is the whole design. The entire body — millstones, gearing, miller
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* and all — is balanced on ONE massive vertical post and turns bodily on it, so
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* that the sails can be pointed into whatever wind there is. The miller does
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* that by walking the tail ladder round, which is why the ladder is not a way
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* up but a lever, and why it reaches so far behind the mill.
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*
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* That gives the model its four parts and the order they have to be built in:
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*
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* - `trestle` — two cross-trees laid on the ground, the post standing on
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* them, and four quarter-bars bracing post to cross-tree. Nothing is
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* fastened to the ground: a post mill stands on its own weight, and the
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* cross-trees are what stop it walking off.
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* - `body` — the buck, a boarded timber box with a pitched roof, sitting on
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* the post's crown.
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* - `sails` — four lattice sails on a windshaft that leaves the front gable
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* tilted a little upwards. This part has its own origin at the shaft, so
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* `setTurning` can spin it without moving anything else.
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* - `ladder` — the tail ladder, from the back of the buck down to the ground
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* well behind it.
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*
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* The sails are the reason the triangle count is where it is. A sail is not a
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* blade, it is a LATTICE: a whip with a frame beside it and a run of bars
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* across, which the miller dresses with canvas according to the wind. Drawn as
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* a solid blade the silhouette is wrong in the one place everybody looks, so
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* the bars are modelled and the budget is spent there rather than on the
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* boarding of the buck, which reads perfectly well as vertex colour.
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*
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* THIRD PASS. The critique before this one scored 66 and its worst axis was
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* material, and the cause was arithmetic, not taste: oak's linear lightness is
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* about 0.067 and the tinter's default jitter is +-0.05, so every default-
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* spread tint call was rolling nearly the whole palette range, and lifts like
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* -0.12 (roof) and -0.22 (door ledges) slammed into the tinter's 0.045 floor
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* and came out near-black. Everything timber now goes through one local
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* `wood()` helper: lifts within +-0.04, spread ~0.3, and saturation halved
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* after tinting (safe to mutate -- the tinter returns a new Color) so the
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* whole mill sits in one weathered silver-grey family, roof a step LIGHTER
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* than the walls as weathered shingle is, and the only dark note is a new
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* wrought-iron canister boss at the sail crossing where the old pale bands
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* were. Also this pass: each sail gained a solid windboard along the leading
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* edge and a wider lattice so it reads as a blade rather than a bare ladder;
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* the hub came back to 0.70 of the body depth (perspective on the far-forward
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* hub is what made the critic read the arms as unequal -- they never were);
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* the quarter-bars got per-arm foot heights because two arms seat on the
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* UPPER cross-tree and two on the LOWER, and one shared foot height left the
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* lower pair hanging 6 cm above their tree; the buck walls now batter inwards
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* toward the top and the plan is longer along the ridge; and the tail ladder
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* steepened from 38 to about 51 degrees with its foot pulled in by a metre,
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* so it stops competing with the sails for silhouette.
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*/
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import { Color, 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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taperedBoxGeometry,
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} from '../core/index.ts'
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export interface PostMillConfig {
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/** Height to the ridge of the roof (metres). Sails reach past it. */
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readonly height: number
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/** Sail span, tip to tip (metres). */
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readonly sailSpan: number
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/** Bars across each sail. */
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readonly sailBars: number
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/** Width of the lattice beside each whip, as a fraction of the sail's length. */
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readonly sailWidth: number
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/** Rungs in the tail ladder. */
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readonly ladderRungs: number
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/** Current sail angle (radians). */
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readonly spin: number
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readonly seed: number
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}
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export const postMillDefaults: PostMillConfig = {
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height: 6.2,
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// The lowest sail tip has to clear the ground WHILE TURNING: the hard limit
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// is a sail pointing straight down, hub height above ground minus half the
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// span. At 7.4 against a 6.2 m mill that came to 0.27 m, a mill about to
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// plough its own field. 7.0 with the hub at 0.80 of the buck leaves 0.59 m
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// turning and over 1.5 m in the resting X pose the model is drawn in.
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sailSpan: 7.0,
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// The lattice is what says "windmill" at any distance, and nine bars over a
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// 3.3 m sail spaces them like ladder rungs. The reference reads as a fine
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// grid.
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sailBars: 13,
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// The lattice alone at 0.17 of the length read as a bare ladder; with the
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// windboard alongside, 0.22 brings the whole blade to roughly a fifth of
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// its length, which is the reference's proportion.
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sailWidth: 0.22,
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ladderRungs: 13,
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spin: 0,
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seed: 43,
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}
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export type PostMillParts = 'trestle' | 'body' | 'sails' | 'ladder'
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export interface PostMillActions {
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/** Starts or stops the sails. */
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setTurning(on: boolean): void
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isTurning(): boolean
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/** Puts the sails at a given angle and stops them there. */
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setAngle(radians: number): void
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}
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export function createModel(overrides: Partial<PostMillConfig> = {}) {
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let turning = false
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let angle = 0
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return createKitModel<PostMillConfig, 'oak' | 'iron', PostMillParts, PostMillActions>({
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id: 'post-mill',
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defaults: postMillDefaults,
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slots: ['oak', 'iron'],
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build: ({ config, random }) => {
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const tint = createTinter(random)
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/**
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* Every piece of timber on this mill, one weathered family.
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*
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* Two numbers in the tinter make raw `tint('oak', ...)` calls a trap for
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* a model this size. Oak's LINEAR lightness is about 0.067, so the
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* default-spread lightness jitter of +-0.05 spans most of the palette
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* and painted sibling parts in unrelated tones; and any lift beyond
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* about -0.04 lands on the tinter's floor and reads near-black. So:
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* small spread, small lifts, and saturation halved after the fact --
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* safe, because the tinter returns a NEW Color every call -- which is
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* what turns brown sawn oak into the silver-grey of wood left out in
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* the weather for a century.
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*/
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const wood = (lift = 0, spread = 0.3): Color => {
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const colour = tint('oak', lift, spread)
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const hsl = { h: 0, s: 0, l: 0 }
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colour.getHSL(hsl)
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colour.setHSL(hsl.h, hsl.s * 0.5, hsl.l)
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return colour
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}
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const H = config.height
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const half = H / 2
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const floor = -half
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// Heights are fractions of the mill's own height, so every slider keeps
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// the proportions of the reference rather than stretching one piece.
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const postTop = floor + H * 0.42
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const bodyHeight = H * 0.30
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const bodyBottom = postTop
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const bodyTop = bodyBottom + bodyHeight
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const bodyWidth = H * 0.27 // across the sails' axis
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const bodyDepth = H * 0.36 // along it: the plan is longer along the ridge
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// The walls batter: the reference buck is visibly wider at the sill than
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// at the eaves, about 15 percent. Only the width tapers -- keeping the
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// tail wall vertical keeps the door and the gallery flat against it.
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const wallTopWidth = bodyWidth * 0.87
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const ridge = bodyTop + H * 0.15
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// --- Trestle -------------------------------------------------------------
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const timber: BufferGeometry[] = []
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const postSide = H * 0.075
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const treeSpan = H * 0.62
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const treeSide = H * 0.055
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// Two cross-trees, laid one over the other. They are NOT coplanar: the
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// upper one rides on top of the lower, which is how they actually sit and
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// which keeps their faces out of each other.
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for (const [index, along] of ([0, 1] as const).entries()) {
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const lower = index === 0
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const size: [number, number] = along === 0
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? [treeSpan, treeSide]
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: [treeSide, treeSpan]
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timber.push(chamferedBoxGeometry(
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size,
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[size[0] * 0.97, size[1] * 0.97],
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treeSide,
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treeSide * 0.12,
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[0, floor + (lower ? treeSide * 0.5 : treeSide * 1.4), 0],
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wood(lower ? -0.015 : -0.005),
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))
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}
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// The post. Slightly tapered, because it is a whole tree and a tree is.
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const postBase = floor + treeSide * 1.1
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const postHeight = postTop - postBase
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timber.push(taperedBoxGeometry(
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[postSide * 1.15, postSide * 1.15],
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[postSide * 0.92, postSide * 0.92],
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postHeight,
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[0, postBase + postHeight / 2, 0],
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wood(-0.005),
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))
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// Four quarter-bars, one to each arm of the cross-trees. Their feet sit
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// ON the cross-tree and their heads run INTO the post, so both joints are
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// overlaps rather than faces meeting.
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//
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// The foot height is PER ARM. The cross-trees are stacked, so the two
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// arms that run along the upper tree seat a full timber higher than the
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// two along the lower one; a single shared foot height put the lower
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// pair's feet at the upper tree's level, 6 cm above the timber that was
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// actually underneath them, and the critic saw the gap: a brace stopping
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// in mid-air just short of its cross-tree.
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const barFoot = treeSpan * 0.36
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const barHead = postTop - H * 0.075
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for (let i = 0; i < 4; i += 1) {
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const a = (i / 4) * Math.PI * 2
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// Arms at a = 0 and PI run along the upper (z) tree, the other two
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// along the lower (x) tree: the same order the trees were laid in.
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const onUpper = i % 2 === 0
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const footY = floor + treeSide * (onUpper ? 1.45 : 0.62)
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const barRise = barHead - footY
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const barLength = Math.hypot(barFoot, barRise)
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const bar = chamferedBoxGeometry(
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[H * 0.036, H * 0.05],
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[H * 0.03, H * 0.042],
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barLength * 1.04,
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H * 0.006,
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[0, 0, 0],
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wood(-0.01 + jitter(random, 0.008)),
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)
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// Built upright, leaned outwards, then swung to its arm. Rotating about
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// X leans it in the YZ plane; rotating about Y carries that lean round.
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//
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// The sign is NEGATIVE, and it was not. `rotateX(+t)` carries the bar's
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// top towards +Z and the translate below moves it +Z as well, so the
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// two add and the quarter-bars stood on their heads -- feet gathered at
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// the post, heads splayed out over the cross-trees, which is precisely
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// backwards for a brace whose whole job is to carry the post's load out
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// to the ground. Nothing caught it: the bar joins post to cross-tree
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// either way round, so the mass stays connected and the bounding box is
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// identical. It surfaced in the cauldron, where the same expression
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// built a tripod standing on its apex and the support check finally had
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// something to say.
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bar.rotateX(-Math.atan2(barFoot, barRise))
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bar.rotateY(a)
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bar.translate(
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Math.sin(a) * barFoot * 0.5,
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(footY + barHead) / 2,
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Math.cos(a) * barFoot * 0.5,
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)
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timber.push(bar)
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}
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// Crown: the beam the whole body turns on, laid across the post's head.
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// Wide enough that it visibly projects past BOTH walls -- at 1.05 x the
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// body width the projection was 4 cm a side, swallowed by perspective,
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// and the critic read it as a block hanging off one side only.
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timber.push(chamferedBoxGeometry(
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[bodyWidth * 1.14, H * 0.09],
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[bodyWidth * 1.08, H * 0.08],
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H * 0.05,
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H * 0.006,
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[0, postTop - H * 0.012, 0],
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wood(0.008),
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))
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// --- Body ----------------------------------------------------------------
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const shell: BufferGeometry[] = []
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shell.push(chamferedBoxGeometry(
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[bodyWidth, bodyDepth],
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[wallTopWidth, bodyDepth * 0.99],
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bodyHeight,
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H * 0.008,
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[0, bodyBottom + bodyHeight / 2, 0],
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wood(0.012, 0.25),
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wood(0, 0.25),
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))
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// Plank language. The reference wall is mostly vertical board lines, and
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// a bare box carries none of that, which the critique named second after
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// the palette. Vertex colour cannot stripe a single box, so the language
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// is battens: proud vertical strips on both side walls, leaned to the
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// same batter as the wall face so they lie along it rather than pulling
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// away from it towards the eave. Their outer faces are parallel to the
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// wall's, never in its plane.
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const wallLean = Math.atan2((bodyWidth - wallTopWidth) / 2, bodyHeight)
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const wallMidX = (bodyWidth + wallTopWidth) / 4
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for (const side of [-1, 1] as const) {
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for (let b = 0; b < 5; b += 1) {
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const z = ((b + 0.5) / 5 - 0.5) * bodyDepth * 0.88
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const batten = chamferedBoxGeometry(
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[H * 0.012, H * 0.046],
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[H * 0.01, H * 0.04],
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bodyHeight * 0.9,
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H * 0.003,
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[0, 0, 0],
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wood(-0.007 + jitter(random, 0.006), 0.25),
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)
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batten.rotateZ(side * wallLean)
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batten.translate(side * (wallMidX + H * 0.003), bodyBottom + bodyHeight / 2, z)
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shell.push(batten)
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}
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}
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// Roof: a solid gable wedge closing the top of the buck, two boarded
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// pitch slabs lying on its slopes, and a ridge board over the apex.
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//
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// The wedge is this pass's fix. The roof used to be ONLY the two thin
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// slabs, leaned over a flat-topped box: from anywhere above eave height
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// the buck's bare top face showed between them, and the triangular
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// gable under each end of the ridge was open sky. The critic read the
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// result as two disjoint roof planes at different heights with a gap at
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// the gable, and the critic was right. A pitched roof is a solid, not
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// two planes; the wedge fills wall-top to ridge, so the gable ends are
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// boarded and there is nothing to see between the pitches.
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const roofRise = ridge - bodyTop
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// Sunk 3 cm into the buck so its bottom face hides inside that solid
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// instead of sharing the plane of the buck's top face, and inset a
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// little so its gable faces do not share the walls' planes either.
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const wedgeSink = 0.03
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const wedgeRise = roofRise + wedgeSink
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// The wedge sits on the tapered wall top now, so its base matches the
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// wall TOP width, not the sill width.
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const wedgeBase = wallTopWidth * 0.995
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const wedgeHalfRun = (wedgeBase - H * 0.02) / 2
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shell.push(taperedBoxGeometry(
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[wedgeBase, bodyDepth * 0.985],
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[H * 0.02, bodyDepth * 0.985],
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wedgeRise,
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[0, bodyTop - wedgeSink + wedgeRise / 2, 0],
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wood(0.012, 0.25),
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wood(0.03, 0.25),
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))
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// The slabs match the wedge's own pitch and are pushed out along the
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// slope normal by a whisker LESS than half their thickness, so their
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// undersides sit just inside the wedge -- interpenetrating, never
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// coplanar -- and their tops are the shingled surface. Extra length is
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// shoved downhill so it becomes eave overhang past the walls rather
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// than a crossing at the ridge, and extra depth overhangs the gables.
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const pitchAngle = Math.atan2(wedgeRise, wedgeHalfRun)
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const slopeLength = Math.hypot(wedgeRise, wedgeHalfRun)
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const slabT = H * 0.016
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for (const side of [-1, 1]) {
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const pitch = chamferedBoxGeometry(
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[slopeLength * 1.28, bodyDepth * 1.06],
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[slopeLength * 1.28, bodyDepth * 1.06],
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slabT,
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H * 0.004,
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[0, 0, 0],
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// LIGHTER than the walls, not darker. Weathered shingle bleaches
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// ahead of the boarding under it, and this slab at -0.12 was the
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// near-black roof the critique led with: on a palette whose oak
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// lightness is 0.067 linear, -0.12 is the floor. Matching the
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// wedge's top tone also stops the slab's edge reading as a black
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// band where the two roof solids meet along the eave.
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wood(0.035, 0.25),
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)
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// The slab starts lying FLAT -- `chamferedBoxGeometry` takes an X-Z
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// footprint and a Y height -- so the tilt is the pitch angle from the
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// horizontal, negative on the +X side so the eave drops rather than
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// rises. Both earlier attempts used the complement of this angle,
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// which stood the pitches up like the covers of an open book.
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pitch.rotateZ(-side * pitchAngle)
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const midX = (wedgeBase / 2 + H * 0.01) / 2
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const midY = bodyTop - wedgeSink + wedgeRise / 2
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const downhill = slopeLength * 0.11
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const slabX = side * (midX + Math.sin(pitchAngle) * slabT * 0.35 + Math.cos(pitchAngle) * downhill)
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const slabY = midY + Math.cos(pitchAngle) * slabT * 0.35 - Math.sin(pitchAngle) * downhill
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pitch.translate(slabX, slabY, 0)
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shell.push(pitch)
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// Shingle courses: three thin strips per pitch, parallel to the ridge
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// and slightly proud of the slab, sunk a quarter of their thickness
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// into it so they are joined solids rather than sheets lying on a
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// face. Without some course lines the roof reads as painted card, and
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// the critique called the missing shingle language out by name.
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for (let course = 0; course < 3; course += 1) {
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const strip = chamferedBoxGeometry(
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[H * 0.028, bodyDepth * 1.02],
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[H * 0.024, bodyDepth * 1.0],
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slabT * 0.55,
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H * 0.002,
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[0, 0, 0],
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wood(0.028 + jitter(random, 0.006), 0.25),
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)
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strip.rotateZ(-side * pitchAngle)
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const along = (course - 1) * slopeLength * 0.32
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const out = slabT * 0.5 + slabT * 0.55 * 0.5 - slabT * 0.25
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strip.translate(
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slabX + side * (Math.sin(pitchAngle) * out + Math.cos(pitchAngle) * along),
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slabY + Math.cos(pitchAngle) * out - Math.sin(pitchAngle) * along,
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0,
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)
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shell.push(strip)
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}
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}
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// Ridge board, capping the line where the two slabs cross.
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shell.push(chamferedBoxGeometry(
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[H * 0.03, bodyDepth * 1.1],
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[H * 0.024, bodyDepth * 1.1],
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H * 0.022,
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H * 0.004,
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[0, ridge + H * 0.002, 0],
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wood(0.02, 0.25),
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))
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// The door, in the tail wall above the gallery.
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//
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// The ladder has to arrive somewhere. A mill is entered from its tail,
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// through the one wall the sails never sweep past, and the miller comes
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// up the same ladder he turns the mill with -- so a flight of steps
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// ending at blank boarding is the one thing about this model that could
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// not be true.
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//
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// Boarded proud of the wall rather than cut into it: there are no
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// booleans here, and a door of applied planks with a frame round it is
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// how a plank building is actually closed.
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const doorWidth = bodyWidth * 0.42
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const doorHeight = bodyHeight * 0.66
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const doorY = bodyBottom + H * 0.035 + doorHeight / 2
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const doorZ = -bodyDepth / 2
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shell.push(chamferedBoxGeometry(
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[doorWidth, H * 0.018],
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[doorWidth * 0.99, H * 0.016],
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doorHeight,
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H * 0.004,
|
|
[0, doorY, doorZ - H * 0.004],
|
|
// A plank tone a shade darker than the wall, not the pure black slab
|
|
// the critique saw: -0.14 was through the tinter's floor.
|
|
wood(-0.022, 0.25),
|
|
))
|
|
// Two iron-dark ledges across it, and the frame: what stops a plank door
|
|
// being a rectangle drawn on a wall.
|
|
for (const at of [-0.28, 0.3]) {
|
|
shell.push(chamferedBoxGeometry(
|
|
[doorWidth * 1.04, H * 0.012],
|
|
[doorWidth * 1.02, H * 0.01],
|
|
H * 0.022,
|
|
H * 0.003,
|
|
[0, doorY + doorHeight * at, doorZ - H * 0.012],
|
|
wood(-0.034, 0.25),
|
|
))
|
|
}
|
|
|
|
// The tail gallery: the little platform the ladder arrives at.
|
|
shell.push(chamferedBoxGeometry(
|
|
[bodyWidth * 0.92, H * 0.05],
|
|
[bodyWidth * 0.88, H * 0.045],
|
|
H * 0.018,
|
|
H * 0.004,
|
|
[0, bodyBottom + H * 0.02, -bodyDepth * 0.52],
|
|
wood(-0.008),
|
|
))
|
|
|
|
// --- Sails ---------------------------------------------------------------
|
|
// The windshaft leaves the front gable pointing +Z and tilted up a little,
|
|
// which is what stops the sails striking the body as they come round.
|
|
// The sail disc has to clear the front of the buck.
|
|
//
|
|
// A tilted shaft spreads its sails through Z: at 0.14 rad a 3.5 m sail
|
|
// swings +-0.49 m fore and aft, and with the hub only 0.08 m in front of
|
|
// the gable the whole lower half of the disc passed through the building.
|
|
// Two changes, and both are what a real mill does. The shaft tilts only a
|
|
// few degrees -- just enough to keep the sails off the body and to take
|
|
// some of their weight onto the thrust bearing -- and it projects a good
|
|
// way out, so the sweep happens clear of the wall.
|
|
const shaftTilt = 0.075
|
|
// Far enough forward and no further. The clearance the disc needs is
|
|
// sailLength * sin(tilt), about 0.26 m here; pushing the hub out to 0.86
|
|
// of the body's depth left the sails hanging most of a metre off the
|
|
// gable with nothing but the shaft between them, where the reference has
|
|
// them sweeping close past the boarding. Pulled in again from 0.74: the
|
|
// forward hub under a perspective camera is why the critic measured the
|
|
// near arm 25 percent longer than its opposite -- the four arms are
|
|
// identical -- and every centimetre back shrinks that distortion. At
|
|
// 0.68 the rear stock's sweep still clears the roof overhang by ~5 cm.
|
|
const hubZ = bodyDepth * 0.68
|
|
// High on the gable end, not at the gallery. At 0.72 the hub sat far
|
|
// enough below the eave line that from a corner view it read as bolted
|
|
// to the wall at gallery height; the reference carries it just under
|
|
// the eave, so the sails radiate from beneath the roof apex.
|
|
const hubY = bodyBottom + bodyHeight * 0.80
|
|
const sailLength = config.sailSpan / 2
|
|
const hubRadius = H * 0.035
|
|
const barT = H * 0.014
|
|
const latticeWidth = sailLength * config.sailWidth
|
|
const bars = Math.max(2, Math.round(config.sailBars))
|
|
|
|
const rig: BufferGeometry[] = []
|
|
const ironWork: BufferGeometry[] = []
|
|
// Windshaft: iron-banded oak, poking out of the gable ALONG Z.
|
|
//
|
|
// `taperedBoxGeometry` takes its third argument as a Y height, so written
|
|
// without a rotation this was a short vertical post standing inside the
|
|
// buck rather than a shaft projecting from the front of it. Hidden inside
|
|
// the body it went unseen through every render; it only surfaced when the
|
|
// iron bands were added and turned out to be coaxial with it, which the
|
|
// z-fight check reported at once.
|
|
// Long enough to reach back into the gable it comes out of.
|
|
const shaftLength = H * 0.20
|
|
const shaft = taperedBoxGeometry(
|
|
[hubRadius * 2.1, hubRadius * 2.1],
|
|
[hubRadius * 1.5, hubRadius * 1.5],
|
|
shaftLength,
|
|
[0, 0, 0],
|
|
wood(-0.008),
|
|
)
|
|
shaft.rotateX(Math.PI / 2)
|
|
shaft.translate(0, 0, -shaftLength * 0.32)
|
|
rig.push(shaft)
|
|
// The canister boss: one dark iron block at the crossing, holding both
|
|
// stocks to the shaft. It replaces the two thin iron bands of the last
|
|
// pass, which at +0.02 lift with the iron material's low roughness came
|
|
// out PALE blue-grey -- a colour used nowhere else -- and, sitting at
|
|
// -0.02 and +0.03 along the shaft, read as a chip floating beside the
|
|
// cross rather than the thing joining it. This block is centred on the
|
|
// crossing, deep enough along the shaft to swallow both whips where
|
|
// they pass (they interpenetrate it on purpose), and it is the darkest
|
|
// value on the whole model: everything else moved up into one pale
|
|
// weathered family, and the boss is the single iron note the reference
|
|
// keeps dark.
|
|
ironWork.push(boxGeometry(
|
|
[bodyWidth * 0.155, bodyWidth * 0.155, barT * 6.0],
|
|
[0, 0, 0],
|
|
tint('iron', -0.02, 0.4),
|
|
))
|
|
|
|
// The stocks: TWO continuous timbers, each passing right through the
|
|
// crossing and carrying a sail at both ends, one behind the other along
|
|
// the shaft. Last pass built four separate whips instead, each STARTING
|
|
// at the hub radius, and the critic measured the arms as unequal --
|
|
// they were equal, but four inner ends loitering near a perspective-
|
|
// distorted hub gave it four slightly different crossings to guess at.
|
|
// A through stock cannot have that problem: both of its arms are the
|
|
// same timber.
|
|
for (const [index, off] of ([-1, 1] as const).entries()) {
|
|
const stock = boxGeometry(
|
|
[barT * 1.3, config.sailSpan * 0.995, barT * 1.6],
|
|
[0, 0, 0],
|
|
wood(-0.008 + jitter(random, 0.008)),
|
|
)
|
|
if (index === 1) stock.rotateZ(Math.PI / 2)
|
|
stock.translate(0, 0, off * barT * 2.1)
|
|
rig.push(stock)
|
|
}
|
|
|
|
for (let i = 0; i < 4; i += 1) {
|
|
const a = (i / 4) * Math.PI * 2
|
|
const sail: BufferGeometry[] = []
|
|
|
|
// The outer rail of the frame, parallel to the stock.
|
|
sail.push(boxGeometry(
|
|
[barT * 0.9, (sailLength - hubRadius) * 0.9, barT * 1.1],
|
|
[latticeWidth, hubRadius + (sailLength - hubRadius) * 0.5, 0],
|
|
wood(-0.012),
|
|
))
|
|
// The bars across. A solid blade would read as a propeller; the
|
|
// lattice is what says "windmill" at any distance.
|
|
for (let b = 0; b < bars; b += 1) {
|
|
const t = (b + 0.6) / bars
|
|
sail.push(boxGeometry(
|
|
[latticeWidth * 1.12, barT * 0.7, barT * 0.9],
|
|
[latticeWidth * 0.5, hubRadius + (sailLength - hubRadius) * t, 0],
|
|
wood(0.005 + jitter(random, 0.01)),
|
|
))
|
|
}
|
|
// The windboard: the solid plank running the length of the leading
|
|
// edge, on the opposite side of the stock from the lattice. This is
|
|
// what makes a sail read as a BLADE rather than a bare ladder, and
|
|
// its absence was the critique's second fix. Thicker than both the
|
|
// bars and the stock's own plane so no face of it is coplanar with
|
|
// either where they interpenetrate.
|
|
sail.push(boxGeometry(
|
|
[latticeWidth * 0.48, (sailLength - hubRadius) * 0.94, barT * 1.15],
|
|
[-latticeWidth * 0.24 + barT * 0.5, hubRadius + (sailLength - hubRadius) * 0.5, 0],
|
|
wood(0.022, 0.25),
|
|
))
|
|
|
|
const merged = mergeColoured(sail)
|
|
// Cant: each sail is twisted a few degrees about its own length so it
|
|
// presents a face to the wind. Without it the four read as a flat cross.
|
|
merged.rotateY(0.18)
|
|
merged.rotateZ(a)
|
|
// Each lattice sits at its own stock's depth along the shaft.
|
|
merged.translate(0, 0, (i % 2 === 0 ? -1 : 1) * barT * 2.1)
|
|
rig.push(merged)
|
|
}
|
|
|
|
const sails = mergeColoured(rig)
|
|
const shaftBands = mergeColoured(ironWork)
|
|
shaftBands.rotateX(-shaftTilt)
|
|
// The resting pose is an X, baked in BEFORE the tilt so `spin` stays a
|
|
// plain rotation about the shaft. Built as a "+" the mill parks with
|
|
// one sail hidden against the roofline and one dead horizontal, and the
|
|
// horizontal one reads as a railed walkway running off into space --
|
|
// which is exactly what the critique saw. The reference parks in an X,
|
|
// two sails up and two down, and so does every mill at rest: the X is
|
|
// the pose that keeps canvas, weight and lightning-conductor happy.
|
|
sails.rotateZ(Math.PI / 4)
|
|
// The rig is authored around the hub and the part's origin goes there, so
|
|
// `setTurning` spins it about the shaft instead of about the model.
|
|
sails.rotateX(-shaftTilt)
|
|
|
|
// --- Ladder --------------------------------------------------------------
|
|
const steps: BufferGeometry[] = []
|
|
// Steeper than a lever wants, shallower than a stair. Every earlier pass
|
|
// reasoned from what a tail ladder DOES and reached 0.56 of the height,
|
|
// about 38 degrees -- and the critic, twice now, has read that reach as
|
|
// a gangplank competing with the sails for the silhouette. The reference
|
|
// has no ladder at all, so the ladder earns its keep only while it stays
|
|
// out of the way: 0.36 brings it to about 51 degrees with the foot a
|
|
// metre and a half closer in, clearly a way up the back of the buck.
|
|
const footZ = -bodyDepth * 0.5 - H * 0.36
|
|
const headZ = -bodyDepth * 0.52
|
|
const headY = bodyBottom + H * 0.02
|
|
const run = headZ - footZ
|
|
const rise = headY - floor
|
|
const railLength = Math.hypot(run, rise)
|
|
const lean = Math.atan2(run, rise)
|
|
const railGap = bodyWidth * 0.34
|
|
|
|
// The whole ladder is lifted by one offset, rails and rungs together.
|
|
//
|
|
// The foot has to land ON the ground, level with the cross-trees, and two
|
|
// things push it under. The rail is built 3% long so it can bury its head
|
|
// in the gallery, and half of that overrun hangs off the bottom; and once
|
|
// tilted, the lowest CORNER of its end face drops below that face's
|
|
// centre by half the rail's depth times sin(lean). Left uncorrected the
|
|
// ladder sat 0.10 m under the trestle, so the mill's floor was its stair
|
|
// and the whole thing hovered above whatever it was placed on.
|
|
//
|
|
// Correcting only the rails is worse than not correcting at all. The
|
|
// second term displaces them PERPENDICULAR to their own axis by very
|
|
// nearly a rung's half-depth, so the rungs -- placed on the original
|
|
// centre line -- came away from the rails entirely. The support audit
|
|
// caught that at the small end of the height slider as loose rungs
|
|
// floating beside the ladder.
|
|
const railDepth = H * 0.038
|
|
const liftY = railLength * 0.015 * Math.cos(lean) + (railDepth / 2) * Math.sin(lean)
|
|
const liftZ = -railLength * 0.015 * Math.sin(lean)
|
|
|
|
for (const side of [-1, 1]) {
|
|
const rail = chamferedBoxGeometry(
|
|
[H * 0.022, railDepth],
|
|
[H * 0.018, H * 0.032],
|
|
railLength * 1.03,
|
|
H * 0.004,
|
|
[0, 0, 0],
|
|
wood(-0.012),
|
|
)
|
|
// +lean, not -lean. `run` is positive -- the ladder's head sits at a
|
|
// LARGER z than its foot -- and rotateX(+t) carries +Y towards +Z, so
|
|
// the negative sign laid the rails along the opposite diagonal to the
|
|
// one the rungs are placed on. The two crossed near the middle and
|
|
// diverged towards the ends, which is exactly what the support audit
|
|
// reported: the middle rungs held, the outer ones floated. The bounding
|
|
// box looked right the whole time, because the translation put the
|
|
// ladder where it belonged and only its internals were wrong.
|
|
rail.rotateX(lean)
|
|
rail.translate(
|
|
side * railGap,
|
|
(floor + headY) / 2 + liftY,
|
|
(footZ + headZ) / 2 + liftZ,
|
|
)
|
|
steps.push(rail)
|
|
}
|
|
|
|
const rungs = Math.max(2, Math.round(config.ladderRungs))
|
|
for (let i = 0; i < rungs; i += 1) {
|
|
const t = (i + 0.5) / rungs
|
|
// Spanning PAST both rails, so each rung is housed in them rather than
|
|
// ending at their inner faces.
|
|
// The rung is DEEPER than the rail it passes through (0.048 against
|
|
// 0.038), so its faces stand proud on both sides.
|
|
//
|
|
// Made thinner than the rail, a rung that "passes through" it has its
|
|
// whole surface buried inside the rail's hollow interior, touching
|
|
// nothing: these are surfaces, not solids. At the default height the
|
|
// voxel grid was coarse enough to bridge the gap and the support check
|
|
// passed; shrink the mill to the bottom of the height slider and the
|
|
// finer grid separated three of the five rungs from the ladder. The
|
|
// check was right both times -- the joint was never real.
|
|
const rung = boxGeometry(
|
|
[railGap * 2 + H * 0.03, H * 0.02, H * 0.048],
|
|
[0, 0, 0],
|
|
wood(-0.005 + jitter(random, 0.008)),
|
|
)
|
|
rung.rotateX(lean)
|
|
rung.translate(0, floor + rise * t + liftY, footZ + run * t + liftZ)
|
|
steps.push(rung)
|
|
}
|
|
|
|
/**
|
|
* Then MEASURE the foot and put it on the ground, rather than reasoning
|
|
* about where it ended up.
|
|
*
|
|
* `liftY` above is two analytic corrections to the same corner, and both
|
|
* are right about the thing they describe. What neither accounts for is
|
|
* the chamfer: the rail is a chamfered box, so the corner they compute
|
|
* the drop of has been cut off, and the ladder came to rest 14.5 mm high
|
|
* — very nearly the chamfer itself. That is the third arithmetic mistake
|
|
* at this one corner; the comments above are the first two.
|
|
*
|
|
* A bounding box cannot be wrong about this the way a derivation can, and
|
|
* it stays right when the chamfer, the taper or the rail section change.
|
|
* The head is buried in the gallery by a 3% overrun that is several times
|
|
* this shift, so moving the assembly does not pull it out.
|
|
*/
|
|
const ladder = mergeColoured(steps)
|
|
ladder.computeBoundingBox()
|
|
ladder.translate(0, floor - ladder.boundingBox!.min.y, 0)
|
|
|
|
return {
|
|
trestle: { slot: 'oak' as const, geometry: mergeColoured(timber) },
|
|
body: { slot: 'oak' as const, geometry: mergeColoured(shell) },
|
|
sails: {
|
|
slot: 'oak' as const,
|
|
geometry: sails,
|
|
// The bands belong here, not with the trestle. They are authored
|
|
// around the hub, so in any other part's frame they land at the
|
|
// model's origin and hang in the air -- which is where the support
|
|
// check found them. They also turn with the shaft, because in a real
|
|
// mill the shaft is what the sails are keyed to.
|
|
extras: [{ slot: 'iron' as const, geometry: shaftBands }],
|
|
origin: [0, hubY, hubZ] as const,
|
|
},
|
|
ladder: { slot: 'oak' as const, geometry: ladder },
|
|
}
|
|
},
|
|
|
|
actions: ({ parts, getConfig }) => {
|
|
angle = getConfig().spin
|
|
parts.sails.anchor.rotation.z = angle
|
|
return {
|
|
setTurning: (on) => { turning = on },
|
|
isTurning: () => turning,
|
|
setAngle: (radians) => {
|
|
turning = false
|
|
angle = radians
|
|
parts.sails.anchor.rotation.z = angle
|
|
},
|
|
}
|
|
},
|
|
|
|
update: (deltaSeconds, { parts }) => {
|
|
if (!turning) return
|
|
// A working post mill turns slowly — on the order of ten revolutions a
|
|
// minute at the sail tips, not the blur people draw.
|
|
angle += deltaSeconds * 1.05
|
|
parts.sails.anchor.rotation.z = angle
|
|
},
|
|
}, overrides)
|
|
}
|