Add the first five contemporary props, and give the contact shadow a per-pixel height falloff.

contemporary-props/models/wine-glass/model.ts

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+/**
+ * @contemporary-props/wine-glass
+ *
+ * Second object in the kit, and it is here to prove two things before anything
+ * expensive depends on them: wall thickness on a revolve, and the glass slot.
+ *
+ * The vase got away with a wall of zero thickness because ceramic is opaque
+ * and the bore is dark. Glass is not opaque. Look through a wine glass and
+ * what you actually see of it is its edges: the bright ellipse of the rim, the
+ * disc edge of the foot, and the thick mass where the bowl closes onto the
+ * stem. So the bowl here is a real shell: the profile runs UP the outside,
+ * steps across the rim, and comes back DOWN the inside to a dished floor that
+ * sits well above the outer bottom. That step across the rim is the whole
+ * point — a single-surface bowl in a transparent material has a rim one
+ * triangle wide, which flickers, and a bowl bottom with nothing in it, which
+ * reads as a soap bubble on a stick.
+ *
+ * One continuous lathe carries foot, stem, bowl and inner surface. Not three
+ * stacked pieces, for the reason the lathe exists at all: stacked revolves
+ * leave coincident faces where they meet, and in a transparent material every
+ * internal face is visible forever.
+ *
+ * The stem is the hard part of the silhouette. Too thick and the object is a
+ * goblet; too thin and at prop distance it disappears and the bowl floats.
+ * The config exposes it, clamped to 3.5–8 mm radius, which spans a delicate
+ * tasting glass to a sturdy bistro stem and nothing outside what a stem is.
+ *
+ * The family: bowl radius and rim tuck move it from a wide tucked-in red
+ * through a narrower white to a small open port glass; bowl depth against
+ * total height trades stem for bowl.
+ *
+ * Parts: `body` alone. Nothing on a wine glass moves, and slicing one revolve
+ * into named thirds would only invent seams.
+ */
+import { type BufferGeometry } from 'three'
+
+import {
+  createKitModel,
+  createTinter,
+  jitter,
+  latheGeometry,
+  mergeColoured,
+  smoothNormals,
+  type Level,
+} from '../core/index.ts'
+
+export interface WineGlassConfig {
+  /** Overall height (metres). */
+  readonly height: number
+  /** Widest radius of the bowl (metres). */
+  readonly bowlRadius: number
+  /** Bowl height as a fraction of the overall height. */
+  readonly bowlFraction: number
+  /** Rim radius as a fraction of the bowl radius. Low values tuck the rim in. */
+  readonly rim: number
+  /** Stem radius (metres). The goblet/disappearing line is clamped at both ends. */
+  readonly stemRadius: number
+  /** Sides around the revolve. */
+  readonly segments: number
+  readonly seed: number
+}
+
+export const wineGlassDefaults: WineGlassConfig = {
+  height: 0.215,
+  bowlRadius: 0.044,
+  // Just under half. More bowl than this reads as a brandy balloon, more stem
+  // reads as laboratory glassware.
+  bowlFraction: 0.48,
+  rim: 0.68,
+  stemRadius: 0.0045,
+  segments: 40,
+  seed: 7,
+}
+
+export type WineGlassParts = 'body'
+
+export function createModel(overrides: Partial<WineGlassConfig> = {}) {
+  return createKitModel<WineGlassConfig, 'glass', WineGlassParts>({
+    id: 'wine-glass',
+    defaults: wineGlassDefaults,
+    slots: ['glass'],
+
+    build: ({ config, random }) => {
+      const tint = createTinter(random)
+      const clamp = (v: number, lo: number, hi: number): number => Math.min(hi, Math.max(lo, v))
+
+      const H = clamp(config.height, 0.12, 0.3)
+      const bowlR = clamp(config.bowlRadius, 0.025, Math.min(0.065, H * 0.42))
+      const bowlH = H * clamp(config.bowlFraction, 0.32, 0.62)
+      const rimR = bowlR * clamp(config.rim, 0.52, 0.95)
+      // The stem is clamped twice: absolutely, and against the bowl. The
+      // absolute clamp keeps it a stem at all; the relative one stops a small
+      // glass given a fat stem turning into a candlestick, which is exactly
+      // what the first render of that corner was.
+      const stemR = clamp(config.stemRadius, 0.0035, Math.min(0.008, bowlR * 0.2))
+      // The foot follows the bowl rather than being free: a foot wider than
+      // the bowl is a cake stand, a foot narrower than three stem widths falls
+      // over in the hand and in the eye.
+      const footR = Math.max(bowlR * 0.78, stemR * 3)
+      // Wall thickness scales gently with the bowl so a big balloon does not
+      // end up with cigarette-paper walls, floored where thinner would vanish.
+      const wall = Math.max(0.0016, bowlR * 0.042)
+      const bowlBaseY = H - bowlH
+
+      /**
+       * Outer bowl profile, u = 0 at the stem junction, 1 at the rim.
+       * Below the belly an eased sine gives the rounded bottom; above it a
+       * cosine ease tucks the wall back in toward the rim, with a nonzero
+       * slope at the top so the rim tilts slightly inward like a red should.
+       */
+      const bellyU = 0.45
+      const rOut = (u: number): number =>
+        u <= bellyU
+          ? bowlR * Math.sin((u / bellyU) * (Math.PI / 2)) ** 0.8
+          : rimR + (bowlR - rimR) * Math.cos(((u - bellyU) / (1 - bellyU)) * (Math.PI / 2)) ** 1.35
+      const yAt = (u: number): number => bowlBaseY + bowlH * u
+
+      // The foot's vertical build scales with the glass: fixed heights that
+      // look right on a 21 cm red are a bell jar on a 12 cm port glass.
+      const fs = clamp(H / 0.215, 0.65, 1.15)
+      // Stem levels are fractions of the run between foot and bowl, so a short
+      // glass with a deep bowl cannot fold the stem back through the foot.
+      const footTipY = 0.0165 * fs
+      const s = (t: number): number => footTipY + (bowlBaseY - footTipY) * t
+
+      const levels: Level[] = [
+        // Foot: a disc with a rolled edge, rising as a shallow dome. The edge
+        // band is what the eye gets of the foot through the glass above it.
+        { y: 0, radius: footR * 0.985 },
+        { y: 0.0018 * fs, radius: footR },
+        { y: 0.0032 * fs, radius: footR * 0.94 },
+        { y: 0.007 * fs, radius: footR * 0.5 },
+        { y: 0.0125 * fs, radius: Math.max(footR * 0.2, stemR * 1.9) },
+        { y: footTipY, radius: stemR * 1.5 },
+        // Stem: a hair of entasis. Dead straight looks extruded; the swell at
+        // the top is where the pull into the bowl begins.
+        { y: s(0.22), radius: stemR * 1.06 },
+        { y: s(0.6), radius: stemR * 0.94 },
+        { y: s(0.93), radius: stemR * 1.05 },
+        // Bowl, outside, base to rim. The lowest samples are floored at the
+        // stem radius: on a squat bowl the raw curve starts below the stem and
+        // the profile pinches in before flaring, which reads as a crack.
+        { y: yAt(0.03), radius: Math.max(rOut(0.03), stemR * 1.2) },
+        { y: yAt(0.07), radius: Math.max(rOut(0.07), stemR * 1.45) },
+        { y: yAt(0.13), radius: rOut(0.13) },
+        { y: yAt(0.21), radius: rOut(0.21) },
+        { y: yAt(0.31), radius: rOut(0.31) },
+        { y: yAt(bellyU), radius: bowlR },
+        { y: yAt(0.57), radius: rOut(0.57) },
+        { y: yAt(0.7), radius: rOut(0.7) },
+        { y: yAt(0.82), radius: rOut(0.82) },
+        { y: yAt(0.92), radius: rOut(0.92) },
+        { y: H, radius: rimR },
+        // The rim: two levels at the same height, one wall thickness apart.
+        // The quad between them is the flat annulus that carries the whole
+        // top of the silhouette.
+        { y: H, radius: rimR - wall },
+        // Inside, descending. Same profile inset by the wall, stopped short of
+        // the bottom so the bowl closes onto a solid mass above the stem.
+        { y: yAt(0.92), radius: rOut(0.92) - wall },
+        { y: yAt(0.8), radius: rOut(0.8) - wall },
+        { y: yAt(0.66), radius: rOut(0.66) - wall },
+        { y: yAt(0.52), radius: rOut(0.52) - wall },
+        { y: yAt(bellyU), radius: bowlR - wall },
+        { y: yAt(0.36), radius: rOut(0.36) - wall },
+        { y: yAt(0.27), radius: rOut(0.27) - wall },
+        { y: yAt(0.2), radius: rOut(0.2) - wall },
+        // Dished floor, then the cap closes it. Its height above the outer
+        // base is the thick lens of glass every stemmed glass has where the
+        // bowl was gathered onto the stem, and it is the third edge (after
+        // rim and foot) that makes transparent glass readable.
+        { y: yAt(0.13), radius: bowlR * 0.16 },
+      ]
+
+      const pieces: BufferGeometry[] = [
+        latheGeometry(
+          levels,
+          Math.max(12, Math.round(config.segments)),
+          [0, 0, 0],
+          tint('glass', jitter(random, 0.02)),
+          // Slightly lighter along the run of the profile, which ends on the
+          // inner surface: light collects in the bowl rather than on the foot.
+          { colourTop: tint('glass', 0.05), capBottom: true, capTop: true },
+        ),
+      ]
+
+      // 40 degrees: the walls and the stem are curves and smooth out, while
+      // the rim annulus, the foot edge and the floor cap all turn through
+      // close to a right angle and keep their edges — and on glass the edges
+      // are the object.
+      return {
+        body: { slot: 'glass' as const, geometry: smoothNormals(mergeColoured(pieces), 40) },
+      }
+    },
+  }, overrides)
+}