ImportMeshAsync

SceneLoader.ImportMeshAsync and Its Options

Babylon 89,603 's original loader API is the static class SceneLoader, as in SceneLoader.ImportMeshAsync(meshNames, rootUrl, sceneFilename, scene, onProgress, pluginExtension). Late in the 7.x series (capitalized names since 7.50) module-level functions with one options object replaced it, and 9.28 marks the static methods @deprecated. ImportMeshAsync adds meshes and returns what it created:

Importing one book from the GLB with ImportMeshAsyncJavaScript
// Legacy: BABYLON.SceneLoader.ImportMeshAsync('book3', '', 'booknest-books.glb', scene)
const result = await BABYLON.ImportMeshAsync('booknest-books.glb', scene, {
  meshNames: 'book3',                                  // a name, an array, or '' for all
  onProgress: (event) => console.log(`progress: ${event.loaded} of ${event.total} bytes`),
  pluginOptions: { gltf: { skipMaterials: false, useGltfTextureNames: true } },
});
const [root, book] = result.meshes;                    // __root__ always comes first
console.log(Object.keys(result).join(', '));
console.log(root.name, root.scaling.toString(), book.name, book.metadata.gltf.extras.title);
Output
progress: 1024 of 539408 bytes
progress: 539408 of 539408 bytes
meshes, particleSystems, skeletons, animationGroups, lights, transformNodes, geometries,
  spriteManagers
__root__ {X: 1 Y: 1 Z: -1} book3 Salt and Saffron

The __root__ node flips the file's right-handed data into Babylon's left-handed space (a half turn about y and a z scale of -1), so meshes[0] is never your model. Other gltf options include animationStartMode, loadSkins, loadMorphTargets, compileMaterials (compile shaders while loading), customRootNode and extensionOptions.

ImportMeshAsync picking one book, "book3", out of a six-book GLB, with its __root__ node and extrasHTMLLive
<!doctype html>
<style>
  body { margin: 0; background: #f7f3ec; font: 13px system-ui, sans-serif; color: #333; }
  canvas { width: 100%; max-width: 600px; height: 300px; display: block; touch-action: none; outline: none; }
  #info { max-width: 600px; margin: 0; padding: 4px 8px; font-family: monospace; white-space: pre-wrap; }
</style>
<canvas id="view"></canvas>
<pre id="info">Loading…</pre>
<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 ----

// 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' }
}

const canvas = document.getElementById('view');
const engine = new BABYLON.Engine(canvas, true, {}, true);
const scene = createScene(engine);
const camera = new BABYLON.ArcRotateCamera('cam', -Math.PI / 2 - 0.6, 1.25, 1.3, new BABYLON.Vector3(0, 0.2, 0), scene);
camera.minZ = 0.05;
camera.attachControl(canvas, true);
const plinth = BABYLON.MeshBuilder.CreateCylinder('plinth', { height: 0.1, diameter: 0.7 }, scene);
plinth.position.y = 0.07;
plinth.material = paint(scene, 'walnut', '#6d4c33');
engine.runRenderLoop(() => scene.render());

(async () => {
  const bytes = await createBooksGlb(engine);
  // Legacy: BABYLON.SceneLoader.ImportMeshAsync('book3', '', 'booknest-books.glb', scene)
  const progress = [];
  const result = await BABYLON.ImportMeshAsync(bytes, scene, {
    pluginExtension: '.glb',                           // needed for bytes; a URL's extension says it
    meshNames: 'book3',                                // a name, an array, or '' for all
    onProgress: (event) => progress.push(event.loaded),
    pluginOptions: { gltf: { skipMaterials: false, useGltfTextureNames: true } },
  });
  const [root, book] = result.meshes;                  // __root__ always comes first
  root.position.set(0.1, 0, 0);                       // move the imported group onto the plinth
  scene.onBeforeRenderObservable.add(() => { root.rotation.y += engine.getDeltaTime() / 2500; });
  document.getElementById('info').textContent = `result: ${Object.keys(result).join(', ')}\n` +
    `${root.name} scaling ${root.scaling.toString()}  ->  ${book.name}: "${book.metadata.gltf.extras.title}"` +
    `\nmeshes imported: ${result.meshes.length} (of 7 in the file)`;
})();
addEventListener('resize', () => engine.resize());
</script>