Cover Art Assets

Loading BookNest's Cover Art as glTF Assets

With the books in booknest-books.glb (glTF Loader), an artist can repaint a cover in any glTF tool without touching the shop's code. bookstore.js gains a loader that stocks shelves with copies of the six books, parenting each __root__ to the bookcase and turning the extras back into the records picking reads:

bookstore.js: stocking a bookcase from the GLBJavaScript
async function loadBooks(scene, bookcase, shelves = [2], url = 'booknest-books.glb') { // 7.9.9
  const container = await BABYLON.LoadAssetContainerAsync(url, scene);  // needs the loaders
  const books = [];
  for (const shelf of shelves) {                    // one copy of the six books per shelf
    const { rootNodes } = container.instantiateModelsToScene((name) => `${name}s${shelf}`);
    const root = rootNodes[0];                      // __root__, glTF's handedness flip
    root.parent = bookcase;
    root.position.y = shelf * 0.5;                  // the file's books stand on shelf 0
    for (const book of root.getChildMeshes()) {
      book.metadata = book.metadata.gltf.extras;    // BOOKS[i], carried as glTF extras
      books.push(book);
    }
  }
  return { container, books };                      // clones: each can change material
}

The right-hand bookcase now holds three shelves of loaded books:

BookNest's right bookcase stocked from booknest-books.glbHTML
<canvas id="view" style="width: 620px; height: 190px"></canvas>
<script src="https://cdn.jsdelivr.net/npm/babylonjs@9.28.0/babylon.js"></script>
<script src="bookstore.js"></script>
<script>
(async () => {
  const cdn = 'https://cdn.jsdelivr.net/npm/babylonjs-loaders@9.28.0/';
  await BABYLON.Tools.LoadScriptAsync(cdn + 'babylonjs.loaders.min.js');   // the loaders
  const engine = new BABYLON.Engine(view, true, {}, true);
  const scene = BookNestStore.createScene(engine);
  BookNestStore.createRoom(scene);
  BookNestStore.createBookcase(scene, 'bookcaseLeft', -1.8);
  const right = BookNestStore.createBookcase(scene, 'bookcaseRight', 1.8);
  await BookNestStore.loadBooks(scene, right, [1, 2, 3]);
  await BookNestStore.createFrontWall(scene);
  BookNestStore.lightRoom(scene);                 // after loading, so the new books cast shadows
  const target = new BABYLON.Vector3(1.3, 1.25, 2.6);
  new BABYLON.ArcRotateCamera('browse', -1.75, 1.47, 2.7, target, scene).minZ = 0.05;
  BookNestStore.renderWhenReady(engine, scene, 20);
})();
</script>
Browser output of Listing 7.63
Browser output of 63

They are lit and shadowed like the code-built books, and book2s2.metadata.title reads "Patterns of the Deep Web".

The right bookcase stocked with three shelves of books instantiated from a glTF asset containerHTMLLive
<!doctype html>
<style>
  body { margin: 0; background: #f7f3ec; font: 13px system-ui, sans-serif; color: #333; }
  canvas { width: 100%; max-width: 600px; height: 320px; display: block; touch-action: none; outline: none; }
  #info { max-width: 600px; padding: 4px 8px; font-family: monospace; }
</style>
<canvas id="view"></canvas>
<div id="info">Loading…</div>
<script src="https://cdn.jsdelivr.net/npm/babylonjs@9.28.0/babylon.js"></script>
<script src="https://cdn.jsdelivr.net/npm/babylonjs-loaders@9.28.0/babylonjs.loaders.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/babylonjs-serializers@9.28.0/babylonjs.serializers.min.js"></script>
<script>
// ---- BookNest's bookstore: the helpers the book keeps in bookstore.js ----
const ROOM = { width: 8, depth: 6, height: 3, wall: 0.15 };
const BOOKS = [
  { id: 1, title: 'The Quiet Harbor', author: 'Mara Ellison', color: '#1f5f8b', pages: 312, price: 14.99, rating: 4.6, inStock: true },
  { id: 2, title: 'Patterns of the Deep Web', author: 'Tomas Reyes', color: '#5b3f99', pages: 428, price: 32.5, rating: 4.4, inStock: true },
  { id: 3, title: 'Salt and Saffron', author: 'Priya Nair', color: '#e09a10', pages: 256, price: 24, rating: 4.8, inStock: false },
  { id: 4, title: 'Small Steps to Big Summits', author: 'Dana Whitfield', color: '#3f7d3a', pages: 198, price: 18.5, rating: 4.3, inStock: true },
  { id: 5, title: "The Clockmaker's Paradox", author: 'Julian Voss', color: '#b5452f', pages: 344, price: 16.75, rating: 4.7, inStock: true },
  { id: 6, title: 'Gardens in Glass', author: 'Lena Hart', color: '#2a9d8f', pages: 176, price: 21.3, rating: 4.5, inStock: true },
];
function createScene(engine) {
  const scene = new BABYLON.Scene(engine);
  scene.clearColor = BABYLON.Color4.FromHexString('#cfd8dcff');
  const sky = new BABYLON.HemisphericLight('sky', new BABYLON.Vector3(0.3, 1, -0.4), scene);
  sky.groundColor = new BABYLON.Color3(0.35, 0.32, 0.3);
  return scene;
}
function paint(scene, name, hex) {                  // a matte color
  const material = new BABYLON.StandardMaterial(name, scene);
  material.diffuseColor = BABYLON.Color3.FromHexString(hex);
  material.specularColor = BABYLON.Color3.Black();
  return material;
}
function createRoom(scene) {                        // floor and three walls, front open
  const room = new BABYLON.TransformNode('room', scene);
  const floor = BABYLON.MeshBuilder.CreateGround('floor', { width: ROOM.width, height: ROOM.depth }, scene);
  floor.material = paint(scene, 'oak', '#b08d6a');
  floor.parent = room;
  const plaster = paint(scene, 'plaster', '#fff3e0');
  for (const [name, width, x, z] of [['backWall', 8, 0, 3], ['leftWall', 6, -4, 0], ['rightWall', 6, 4, 0]]) {
    const wall = BABYLON.MeshBuilder.CreateBox(name, { width, height: ROOM.height, depth: ROOM.wall }, scene);
    wall.position.set(x, ROOM.height / 2, z);
    wall.rotation.y = x ? Math.PI / 2 : 0;
    wall.material = plaster;
    wall.parent = room;
  }
  return room;
}
function createBookcase(scene, name, x) {           // 8 boxes merged into 1 mesh
  const [w, h, d, t] = [3, 2.2, 0.35, 0.04];
  const parts = [[t, h, d, -w / 2, h / 2, 0], [t, h, d, w / 2, h / 2, 0], [w, h, t, 0, h / 2, d / 2 - t / 2]];
  for (let i = 0; i < 5; i++) parts.push([w, t, d, 0, 0.1 + i * 0.5, 0]);
  const bookcase = BABYLON.Mesh.MergeMeshes(parts.map(([width, height, depth, px, py, pz]) => {
    const part = BABYLON.MeshBuilder.CreateBox('part', { width, height, depth }, scene);
    part.position.set(px, py, pz);
    return part;
  }), true);
  bookcase.name = name;
  bookcase.material = paint(scene, 'walnut', '#6d4c33');
  bookcase.position.set(x, 0, ROOM.depth / 2 - ROOM.wall / 2 - d / 2);   // against the back wall
  return bookcase;
}
function drawCover(scene, book) {                   // cover art painted on a canvas
  const tex = new BABYLON.DynamicTexture('cover' + book.id, { width: 256, height: 384 }, scene);
  const c = tex.getContext();
  c.fillStyle = book.color; c.fillRect(0, 0, 256, 384);
  c.fillStyle = 'rgba(0,0,0,0.4)'; c.fillRect(0, 0, 18, 384);         // the dark left edge
  c.strokeStyle = '#fff8e1'; c.lineWidth = 3; c.strokeRect(34, 24, 202, 336);
  c.fillStyle = '#fff8e1'; c.textAlign = 'center'; c.font = 'bold 30px Georgia';
  const lines = [''];
  for (const word of book.title.split(' ')) {
    const test = (lines[lines.length - 1] + ' ' + word).trim();
    if (c.measureText(test).width > 180) lines.push(word); else lines[lines.length - 1] = test;
  }
  lines.forEach((line, i) => c.fillText(line, 135, 110 + i * 38));
  c.font = '20px Georgia'; c.fillText(book.author, 135, 330);
  tex.update();
  return tex;
}
function placeBooks(scene, bookcase, shelf = 2) {   // six books, spines out, covers on +x
  const strip = new BABYLON.Vector4(0, 0, 0.07, 1);
  const faceUV = [strip, strip, new BABYLON.Vector4(0, 0, 1, 1), strip, strip, strip];
  let x = -0.35;                                    // left end of the row, local to the bookcase
  return BOOKS.map((record) => {
    const width = record.pages / 4000 + 0.02;       // spine thickness from page count
    const book = BABYLON.MeshBuilder.CreateBox(`book${record.id}`, { width, height: 0.3, depth: 0.22, faceUV, wrap: true }, scene);
    book.parent = bookcase;
    book.position.set(x + width / 2, 0.12 + shelf * 0.5 + 0.15, -0.02);
    x += width + 0.012;
    book.material = new BABYLON.StandardMaterial(record.title, scene);
    book.material.diffuseTexture = drawCover(scene, record);
    book.material.specularColor = new BABYLON.Color3(0.15, 0.15, 0.15);
    book.metadata = record;                         // the record, for picking
    return book;
  });
}
// The book cuts the storefront with CSG2 (Manifold WebAssembly); this sandbox cannot download
// the .wasm, so the older pure-JavaScript BABYLON.CSG makes the same cuts here.
function createFrontWall(scene) {
  const box = (width, height, depth, x, y) => {
    const mesh = BABYLON.MeshBuilder.CreateBox('cut', { width, height, depth }, scene);
    mesh.position.set(x, y, -ROOM.depth / 2);
    return mesh;
  };
  const solid = box(ROOM.width, ROOM.height, ROOM.wall, 0, ROOM.height / 2);
  const windowHole = box(3.2, 1.6, 1, -1.4, 1.6), doorHole = box(1.1, 2.2, 1, 2.3, 1.1);
  const wall = BABYLON.CSG.FromMesh(solid).subtract(BABYLON.CSG.FromMesh(windowHole))
    .subtract(BABYLON.CSG.FromMesh(doorHole)).toMesh('frontWall', scene.getMaterialByName('plaster'), scene);
  [solid, windowHole, doorHole].forEach((mesh) => mesh.dispose());
  return wall;
}
// ---- end of the bookstore helpers ----

function lightRoom(scene) {                         // call after the meshes exist
  scene.getLightByName('sky').intensity = 0.5;      // the sky light becomes fill light
  const sun = new BABYLON.DirectionalLight('sun', new BABYLON.Vector3(0.2, -0.33, 1), scene);
  sun.intensity = 0.8;
  sun.diffuse = BABYLON.Color3.FromHexString('#fff1d6');   // warm afternoon sun
  const ceiling = BABYLON.MeshBuilder.CreateBox('ceiling', { width: ROOM.width, height: ROOM.wall, depth: ROOM.depth }, scene);
  ceiling.position.y = ROOM.height + ROOM.wall / 2;
  ceiling.layerMask = 0x10000000;                   // no camera draws it; it still casts
  const shadows = new BABYLON.CascadedShadowGenerator(2048, sun);
  Object.assign(shadows, { numCascades: 3, shadowMaxZ: 20, lambda: 1,
    autoCalcDepthBounds: true, bias: 0.002, normalBias: 0.01 });
  for (const mesh of scene.meshes) {
    if (mesh.name !== 'floor') shadows.addShadowCaster(mesh);
    mesh.receiveShadows = true;
  }
  const lamp = new BABYLON.PointLight('lamp', new BABYLON.Vector3(-1.2, 2.3, 1.4), scene);
  lamp.diffuse = BABYLON.Color3.FromHexString('#ffd9a0');
  Object.assign(lamp, { intensity: 0.7, range: 5 });   // a warm reading lamp
  return { sun, lamp, shadows };
}

// The book loads booknest-books.glb over HTTP. This sandboxed preview cannot fetch files, so it
// first writes the same GLB in memory (six books with PBR covers and their records as glTF
// extras) with the serializers package, then hands those bytes to the loader.
async function createBooksGlb(engine) {
  const scratch = new BABYLON.Scene(engine);
  const shelf = new BABYLON.TransformNode('shelf', scratch);     // a parent that is not exported
  const books = placeBooks(scratch, shelf, 0);                  // shelf 0: books stand at y 0.27
  books.forEach((book) => {                                     // PBR covers -> glTF materials
    const cover = new BABYLON.PBRMaterial(book.material.name, scratch);
    Object.assign(cover, { albedoTexture: book.material.diffuseTexture, metallic: 0, roughness: 0.5 });
    book.material = cover;
  });
  await scratch.whenReadyAsync();
  const glb = await BABYLON.GLTF2Export.GLBAsync(scratch, 'booknest-books', {
    shouldExportNode: (node) => node.name.startsWith('book'),   // the six books only
    metadataSelector: (metadata) => metadata,                   // BOOKS[i] -> glTF extras
  });
  const bytes = new Uint8Array(await glb.files['booknest-books.glb'].arrayBuffer());
  scratch.dispose();
  return bytes;                                                 // pass with { pluginExtension: '.glb' }
}

async function loadBooks(scene, bookcase, shelves, source) {
  const container = await BABYLON.LoadAssetContainerAsync(source, scene, { pluginExtension: '.glb' });
  const books = [];
  for (const shelf of shelves) {                    // one copy of the six books per shelf
    const { rootNodes } = container.instantiateModelsToScene((name) => `${name}s${shelf}`);
    const root = rootNodes[0];                      // __root__, glTF's handedness flip
    root.parent = bookcase;
    root.position.y = shelf * 0.5;                  // the file's books stand on shelf 0
    for (const book of root.getChildMeshes()) {
      book.metadata = book.metadata.gltf.extras;    // BOOKS[i], carried as glTF extras
      books.push(book);
    }
  }
  return { container, books };                      // clones: each can change material
}

const canvas = document.getElementById('view');
const engine = new BABYLON.Engine(canvas, true, {}, true);
const scene = createScene(engine);
createRoom(scene);
createBookcase(scene, 'bookcaseLeft', -1.8);
const right = createBookcase(scene, 'bookcaseRight', 1.8);
createFrontWall(scene);
const target = new BABYLON.Vector3(1.6, 1.25, 2.6);
const camera = new BABYLON.ArcRotateCamera('browse', -1.75, 1.47, 2.7, target, scene);
camera.minZ = 0.05;
camera.attachControl(canvas, true);
engine.runRenderLoop(() => scene.render());

(async () => {
  const bytes = await createBooksGlb(engine);
  const { books } = await loadBooks(scene, right, [1, 2, 3], bytes);
  lightRoom(scene);                                 // after loading, so the new books cast shadows
  const book = scene.getMeshByName('book2s2');
  document.getElementById('info').textContent =
    `${books.length} books loaded; book2s2.metadata.title = "${book.metadata.title}"`;
})();
addEventListener('resize', () => engine.resize());
</script>