324 lines
14 KiB
TypeScript
324 lines
14 KiB
TypeScript
/**
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* @contemporary-props/gas-cylinder
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*
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* The first time a lathe carries an array, which is the catalogue's whole
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* reason for putting it eighth: the bottle is one revolve, and the guard round
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* its valve is four posts and a ring standing on top of that revolve. Every
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* caged, railed or slatted thing later in the kit is this arrangement again.
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*
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* Measured off the reference. It is 3.72 diameters tall and the parts stack in
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* fractions of that height:
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*
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* 0.000 foot ring, a hair proud of the shell so the bottle stands on a rim
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* 0.116 the shell, straight for half the object
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* 0.608 the shoulder, a dome drawn in to the neck
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* 0.735 neck, 0.36 of the shell's radius
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* 0.761 the valve, in brass because it is the one part that is not steel
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* 0.750 the cage's collar, which sits ON the shoulder rather than the neck
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* 1.000 the cage's top ring
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*
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* The cage is the part worth reading. Its ring is hollow, turned up the
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* outside and back down the inside the way the vase's bore is, because a ring
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* you can see through the middle of is a ring you can see the far side of, and
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* a single-sided one loses that far side to back-face culling. That mistake
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* cost this kit a vase that vanished when you looked into it, and a guard is
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* looked into by definition.
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*
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* The handwheel is its own part with its origin on the valve axis, so
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* `wheel.anchor.rotation.y` is the action. Its lobes are the second array in
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* the model and they are what makes the turn visible: a smooth wheel turns
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* invisibly, which is the same lesson the pepper mill's knurled knob taught.
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*/
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import { type BufferGeometry } from 'three'
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import {
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bakeOcclusion,
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chamferedBoxGeometry,
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createKitModel,
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createTinter,
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jitter,
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latheGeometry,
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mergeColoured,
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smoothNormals,
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type Level,
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} from '../core/index.ts'
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export interface GasCylinderConfig {
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/** Overall height, cage included (metres). */
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readonly height: number
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/** Radius of the shell (metres). */
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readonly radius: number
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/** Posts around the valve guard. */
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readonly posts: number
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/** Lobes around the handwheel. */
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readonly lobes: number
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/** Sides around the revolve. */
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readonly segments: number
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readonly seed: number
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}
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export const gasCylinderDefaults: GasCylinderConfig = {
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height: 0.75,
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// 3.72 diameters tall, which is what the reference measures. A gas bottle
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// squatter than about three reads as a fire extinguisher and taller than
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// about five reads as a pipe.
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radius: 0.101,
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posts: 4,
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lobes: 8,
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segments: 32,
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seed: 17,
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}
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export type GasCylinderParts = 'body' | 'valve' | 'wheel' | 'cage'
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export interface GasCylinderActions {
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/** Turns the handwheel. Default is a quarter turn. */
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turn(radians?: number): void
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}
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export function createModel(overrides: Partial<GasCylinderConfig> = {}) {
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return createKitModel<
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GasCylinderConfig, 'steelPainted' | 'aluminium' | 'brass',
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GasCylinderParts, GasCylinderActions
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>({
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id: 'gas-cylinder',
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defaults: gasCylinderDefaults,
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slots: ['steelPainted', 'aluminium', 'brass'],
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build: ({ config, random }) => {
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const tint = createTinter(random)
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const H = Math.min(1.3, Math.max(0.4, config.height))
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const R = Math.min(H * 0.19, Math.max(H * 0.09, Math.min(0.2, Math.max(0.05, config.radius))))
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const segments = Math.max(12, Math.round(config.segments))
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const posts = Math.max(3, Math.min(8, Math.round(config.posts)))
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const lobes = Math.max(5, Math.min(12, Math.round(config.lobes)))
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const footTop = H * 0.116
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const shellTop = H * 0.608
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const shoulderTop = H * 0.735
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const neckR = R * 0.36
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const neckTop = H * 0.761
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/* -------------------------------------------------------------- shell */
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const shell: Level[] = [
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{ y: 0, radius: R * 1.03 },
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{ y: H * 0.005, radius: R * 1.065 },
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{ y: footTop - H * 0.01, radius: R * 1.065 },
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// The foot ring is a band the shell steps out of, so the bottle stands
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// on a rim rather than on its own wall. Every one of these has one and
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// it is the detail that stops the shape reading as a tin.
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//
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// The step is 6.5%, not 3%. At 3% it is three millimetres on a bottle
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// two hundred across and a critic looking at four renders reported the
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// ring as "effectively 0% and no foot ring at all", which is what an
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// invisible detail is worth.
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{ y: footTop, radius: R },
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{ y: shellTop, radius: R },
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// The shoulder: a dome, sampled so the smoothing takes it as a curve
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// and not as a chain of cones.
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{ y: shellTop + (shoulderTop - shellTop) * 0.35, radius: R * 0.955 },
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{ y: shellTop + (shoulderTop - shellTop) * 0.65, radius: R * 0.84 },
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{ y: shellTop + (shoulderTop - shellTop) * 0.86, radius: R * 0.62 },
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{ y: shoulderTop, radius: neckR * 1.25 },
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{ y: shoulderTop + H * 0.006, radius: neckR },
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{ y: neckTop, radius: neckR },
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]
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const steel = tint('steelPainted', jitter(random, 0.02))
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const vent = tint('steelPainted', -0.16)
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const bodyPieces: BufferGeometry[] = [
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latheGeometry(shell, segments, [0, 0, 0], steel, {
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// A bottle is handled at the neck and stood in the wet, so it is
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// cleaner at the top than at the foot.
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colourTop: tint('steelPainted', 0.05),
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capBottom: true,
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capTop: true,
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}),
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]
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// Two vent holes through the foot ring, which every bottle has so the
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// skirt drains. Dark plugs standing a hair proud rather than holes cut
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// through, because at this size the shadow is the whole of what is seen
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// and a boolean would cost a hundred triangles to say the same thing.
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for (const side of [0.35, -0.35]) {
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const hole = latheGeometry([
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{ y: 0, radius: R * 0.075 },
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{ y: R * 0.02, radius: R * 0.075 },
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], 10, [0, 0, 0], vent, { capBottom: false, capTop: true })
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hole.rotateX(Math.PI / 2)
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hole.rotateY(side * Math.PI)
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hole.translate(
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Math.sin(side * Math.PI) * R * 1.05,
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footTop * 0.45,
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Math.cos(side * Math.PI) * R * 1.05,
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)
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bodyPieces.push(hole)
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}
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/* -------------------------------------------------------------- valve */
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// A brass block on a stem, with one outlet spigot across it. Brass
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// because it is the one part of a gas bottle that never gets painted.
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const brass = tint('brass', jitter(random, 0.02), 0.6)
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const valveY = neckTop
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const valveH = H * 0.093
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const valveR = R * 0.25
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const valvePieces: BufferGeometry[] = [
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latheGeometry([
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{ y: 0, radius: neckR * 0.92 },
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{ y: valveH * 0.16, radius: valveR * 0.78 },
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{ y: valveH * 0.34, radius: valveR },
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{ y: valveH * 0.62, radius: valveR },
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{ y: valveH * 0.72, radius: valveR * 0.62 },
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{ y: valveH, radius: valveR * 0.42 },
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], Math.max(8, Math.round(segments * 0.5)), [0, valveY, 0], brass,
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{ colourTop: tint('brass', 0.05, 0.6), capBottom: true, capTop: true }),
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// The outlet, across the block. Square-shouldered on purpose: it is a
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// machined fitting and the one hard edge in a model of curves.
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//
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// Built AT THE ORIGIN and carried into place afterwards. Built where it
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// belongs and then turned, `rotateZ` swings it about the world origin
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// instead of about itself, and the spigot ends up lying on the floor a
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// valve-height away from the bottle. It did exactly that, and the
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// support check caught it as a second connected component.
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chamferedBoxGeometry(
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[valveR * 0.9, valveR * 0.9], [valveR * 0.78, valveR * 0.78],
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valveR * 2.4, valveR * 0.12,
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[0, 0, 0], brass,
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),
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]
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valvePieces[1]!.rotateZ(Math.PI / 2)
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valvePieces[1]!.translate(valveR * 0.9, valveY + valveH * 0.46, 0)
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/**
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* The outlet's bore.
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*
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* A gas bottle's side outlet is the one hole anybody looks for, and a
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* solid stub does not read as one: the critic counted zero across four
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* views. Turned up the outside and back down the inside so there is a
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* real mouth, the same construction the vase and the guard's ring use.
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*/
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const spigotR = valveR * 0.44
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const spigot = latheGeometry([
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{ y: 0, radius: spigotR },
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{ y: valveR * 0.5, radius: spigotR },
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{ y: valveR * 0.5, radius: spigotR * 0.52 },
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{ y: valveR * 0.1, radius: spigotR * 0.52 },
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], Math.max(8, Math.round(segments * 0.5)), [0, 0, 0],
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tint('brass', -0.03, 0.6), { capBottom: false, capTop: true })
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spigot.rotateZ(-Math.PI / 2)
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spigot.translate(valveR * 1.75, valveY + valveH * 0.46, 0)
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valvePieces.push(spigot)
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/* ---------------------------------------------------------- handwheel */
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const wheelY = valveY + valveH
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const wheelR = R * 0.31
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const alloy = tint('aluminium', jitter(random, 0.02), 0.7)
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const wheelPieces: BufferGeometry[] = [
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latheGeometry([
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{ y: 0, radius: wheelR * 0.3 },
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{ y: H * 0.004, radius: wheelR * 0.62 },
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{ y: H * 0.013, radius: wheelR * 0.66 },
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{ y: H * 0.03, radius: wheelR * 0.5 },
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{ y: H * 0.037, radius: wheelR * 0.26 },
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], Math.max(8, Math.round(segments * 0.5)), [0, 0, 0], alloy,
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{ colourTop: tint('aluminium', 0.05, 0.7), capBottom: true, capTop: true }),
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]
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// The lobes. Without them the wheel is a smooth disc and turning it is
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// invisible, which is the whole reason the action exists.
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for (let i = 0; i < lobes; i += 1) {
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const angle = (i / lobes) * Math.PI * 2
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const lobe = chamferedBoxGeometry(
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[wheelR * 0.42, wheelR * 0.5], [wheelR * 0.3, wheelR * 0.42],
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H * 0.026, wheelR * 0.09,
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[0, 0, 0], alloy,
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)
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lobe.rotateY(angle)
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lobe.translate(Math.sin(angle) * wheelR * 0.72, H * 0.014, Math.cos(angle) * wheelR * 0.72)
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wheelPieces.push(lobe)
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}
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/* --------------------------------------------------------------- cage */
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// The array the catalogue is here for: posts standing on the shoulder,
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// carrying a ring over the valve.
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const cageBase = H * 0.75
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const cageTop = H
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const cageR = R * 0.83
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const ringH = H * 0.055
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const ringT = R * 0.075
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const cagePieces: BufferGeometry[] = []
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// The collar the posts stand on, a band round the base of the neck.
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cagePieces.push(latheGeometry([
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{ y: cageBase - H * 0.016, radius: neckR * 1.32 },
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{ y: cageBase, radius: neckR * 1.5 },
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{ y: cageBase + H * 0.012, radius: neckR * 1.45 },
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], segments, [0, 0, 0], alloy, { capBottom: true, capTop: true }))
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/**
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* The ring, hollow.
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*
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* Up the outside, across the top, down the inside and back under: a
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* guard is a thing you look through, so its far side is seen from the
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* inside every time. One-sided, that far side is back-facing and culled,
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* and the ring loses half of itself. The vase in this kit already paid
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* for that lesson.
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*/
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cagePieces.push(latheGeometry([
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{ y: cageTop - ringH, radius: cageR },
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{ y: cageTop, radius: cageR },
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{ y: cageTop, radius: cageR - ringT },
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{ y: cageTop - ringH, radius: cageR - ringT },
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], segments, [0, 0, 0], alloy, { capBottom: true, capTop: false }))
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// One bar across the opening, which every guard has and which is what
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// the bottle is actually carried by.
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cagePieces.push(chamferedBoxGeometry(
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[(cageR - ringT) * 2.02, ringH * 0.55], [(cageR - ringT) * 2.02, ringH * 0.45],
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ringT * 0.9, ringT * 0.16,
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[0, cageTop - ringH * 0.5, 0], alloy,
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))
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// The posts. Each is a box leaning from the collar out to the ring, made
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// upright and then turned, because a box built along its own slope has
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// its section measured in the wrong plane.
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const postLo = { r: neckR * 1.42, y: cageBase + H * 0.006 }
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const postHi = { r: cageR - ringT * 0.4, y: cageTop - ringH * 0.4 }
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const runR = postHi.r - postLo.r
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const runY = postHi.y - postLo.y
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const postLen = Math.hypot(runR, runY)
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for (let i = 0; i < posts; i += 1) {
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const angle = (i / posts) * Math.PI * 2 + Math.PI / posts
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const post = chamferedBoxGeometry(
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[R * 0.085, R * 0.13], [R * 0.085, R * 0.13],
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postLen, R * 0.02, [0, 0, 0], alloy,
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)
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// Leaned outward in the x-y plane, then carried round to its angle.
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post.rotateZ(-Math.atan2(runR, runY))
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post.translate((postLo.r + postHi.r) / 2, (postLo.y + postHi.y) / 2, 0)
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post.rotateY(angle)
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cagePieces.push(post)
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}
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// The cage's own shadowing, before it is merged: a ring over a valve is
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// mostly gaps, and gaps are what occlusion is for.
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bakeOcclusion(cagePieces, { strength: 0.45 })
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return {
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body: { slot: 'steelPainted' as const, geometry: smoothNormals(mergeColoured(bodyPieces), 40) },
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valve: { slot: 'brass' as const, geometry: smoothNormals(mergeColoured(valvePieces), 35) },
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wheel: {
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slot: 'aluminium' as const,
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geometry: smoothNormals(mergeColoured(wheelPieces), 35),
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origin: [0, wheelY, 0] as const,
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},
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cage: { slot: 'aluminium' as const, geometry: smoothNormals(mergeColoured(cagePieces), 35) },
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}
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},
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actions: ({ parts }) => ({
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turn: (radians = Math.PI / 2) => {
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parts.wheel.anchor.rotation.y += radians
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},
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}),
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}, overrides)
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}
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