PRE-REFINEMENTS

src/render/stack.js

@@ -0,0 +1,112 @@
+/* ============================================================
+   stack.js — split one scene across the printable planes of a
+   physical acrylic stack (front + back of several sheets, air
+   gaps, backlit). The scene model's per-track z and age stop
+   being opacity tricks and become actual millimetres.
+
+   A PLAN describes the piece:
+     { id, seed, size, geometry:{thickness,gap}, params:{...},
+       planes: [ { sheet:'A', face:'back', label,
+                   tracks: false | true | {kinds, z:[lo,hi], age:[lo,hi]},
+                   disk, boundary, optics, damage,        // flags
+                   media: false | true | {reseau,grease,film,splice},
+                   fiducials, header,                     // flags
+                   params: {...per-plane overrides},
+                   fx: { blur, opacity, scale } }, ... ] }
+
+   The scene is generated ONCE from the merged params; each plane
+   renders a filtered copy through the untouched renderSVG with
+   transparentPaper (the backlight is the paper). Bloom/core face
+   pairs must use IDENTICAL track selectors and equal density/size
+   so their salted bubble draws match — same filtered list, same
+   positions; only fx differ.
+
+   Per-plane depth/aging default LOW: the physical stack now
+   carries depth; double-encoding it as opacity fights the medium.
+   ============================================================ */
+import { generateScene } from '../scene/scene.js';
+import { paramsFromSeed } from '../scene/params.js';
+import { renderSVG } from './svgVector.js';
+
+const inRange = (v, r) => !r || (v >= r[0] && v <= r[1]);
+
+function filterTracks(tracks, sel) {
+  if (!sel) return [];
+  if (sel === true) return tracks;
+  return tracks.filter(t =>
+    (!sel.kinds || sel.kinds.includes(t.kind)) &&
+    inRange(t.z ?? 0, sel.z) &&
+    inRange(t.age ?? 0, sel.age));
+}
+
+function filterMedia(media, sel) {
+  if (!media || !sel) return null;
+  if (sel === true) return media;
+  return {
+    reseau: sel.reseau ? media.reseau : null,
+    grease: sel.grease ? media.grease : [],
+    film: sel.film ? media.film : null,
+    splice: sel.splice ? media.splice : null,
+  };
+}
+
+/* wrap a rendered plane in optional blur / opacity / centre-scale
+   (blur is in u = px per 1000; scale is for deliberate moiré offsets) */
+function applyFx(svg, fx, size) {
+  const { blur = 0, opacity = 1, scale = 1 } = fx || {};
+  if (!blur && opacity === 1 && scale === 1) return svg;
+  const u = size / 1000, c = size / 2;
+  const filter = blur
+    ? `<filter id="planefx" x="-15%" y="-15%" width="130%" height="130%"><feGaussianBlur stdDeviation="${(blur * u).toFixed(2)}"/></filter>`
+    : '';
+  const g = `<defs>${filter}</defs><g${blur ? ' filter="url(#planefx)"' : ''}`
+    + `${opacity !== 1 ? ` opacity="${opacity}"` : ''}`
+    + `${scale !== 1 ? ` transform="translate(${c} ${c}) scale(${scale}) translate(${-c} ${-c})"` : ''}>`;
+  return svg.replace(/(<svg[^>]*>)/, `$1\n${g}`).replace(/<\/svg>\s*$/, '</g></svg>\n');
+}
+
+export function renderStack(plan) {
+  const base = { ...paramsFromSeed(plan.seed), ...(plan.params || {}), invert: true };
+  const scene = generateScene(base);
+  const size = plan.size || 1400;
+
+  const planes = plan.planes.map((plane) => {
+    const emit = [];
+    if (plane.disk) emit.push('disk');
+    if (plane.tracks || plane.optics || plane.damage || plane.boundary) emit.push('bubble');
+    if (plane.media || plane.fiducials || plane.header) emit.push('fiduciaries');
+
+    const ps = {
+      ...base,
+      transparentPaper: true, vign: 0,
+      showBoundary: !!plane.boundary,
+      showFiducials: !!plane.fiducials,
+      showHeader: !!plane.header,
+      depth: 0.15, aging: 0.2,          // the stack is the depth model now
+      emit,
+      ...(plane.params || {}),
+    };
+    const sc = {
+      ...scene,
+      tracks: filterTracks(scene.tracks, plane.tracks ?? false),
+      shock: plane.disk ? scene.shock : null,
+      instrument: plane.optics ? scene.instrument : null,
+      artifacts: plane.damage ? scene.artifacts : null,
+      media: filterMedia(scene.media, plane.media),
+    };
+    const svg = applyFx(renderSVG(sc, ps, size), plane.fx, size);
+    return { sheet: plane.sheet, face: plane.face, label: plane.label || '', svg };
+  });
+
+  return { plan, scene, planes };
+}
+
+/* physical z (mm) of each plane from stack geometry; sheet order = first
+   appearance in the plan (back of the stack first) */
+export function planeDepths(plan) {
+  const t = plan.geometry?.thickness ?? 3;
+  const g = plan.geometry?.gap ?? 6;
+  const sheets = [...new Set(plan.planes.map(p => p.sheet))];
+  return plan.planes.map(p =>
+    sheets.indexOf(p.sheet) * (t + g) + (p.face === 'front' ? t : 0));
+}