Room Lighting

Lighting and Shadowing BookNest's Room

BookNest's room gets the sky light turned down to fill, a warm sun through the storefront window, and a reading lamp. The room has no ceiling, so overview cameras can look in, but then the sun would pour over the walls; a ceiling on a layer no camera renders (layerMask) still draws into the shadow map, which ignores layer masks:

bookstore.js: a sun with cascaded shadows, a lamp and a shadow-only ceilingJavaScript
function lightRoom(scene) {                         // Section 7.7.8: call after the meshes
  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 };
}

Every mesh but the floor casts, and all receive. From inside the shop:

BookNest's room lit by sun through the window, with cascaded shadowsHTML
<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 engine = new BABYLON.Engine(view, true, {}, true);
  const scene = BookNestStore.createScene(engine);
  BookNestStore.createRoom(scene);
  const left = BookNestStore.createBookcase(scene, 'bookcaseLeft', -1.8);
  BookNestStore.createBookcase(scene, 'bookcaseRight', 1.8);
  BookNestStore.coverBooks(scene, BookNestStore.placeBooks(scene, left));
  await BookNestStore.createFrontWall(scene);
  BookNestStore.lightRoom(scene);                              // after all the meshes
  const target = new BABYLON.Vector3(-0.8, 0.9, 1.2);
  new BABYLON.ArcRotateCamera('inside', -1.3, 1.25, 3.9, target, scene).minZ = 0.05;
  BookNestStore.renderWhenReady(engine, scene, 20);
})();
</script>
Browser output of Listing 7.43
Browser output of 43

The window's outline falls across the floor and lower shelves, the rest of the room sits in the fill, and the lamp warms the back wall. HDR Room Lighting replaces the flat fill with an HDR environment.

BookNest's room lit by a warm sun through the storefront window, cascaded shadows and a reading lampHTMLLive
<!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; }
</style>
<canvas id="view"></canvas>
<script src="https://cdn.jsdelivr.net/npm/babylonjs@9.28.0/babylon.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 };
}

const canvas = document.getElementById('view');
const engine = new BABYLON.Engine(canvas, true, {}, true);
const scene = createScene(engine);
createRoom(scene);
const left = createBookcase(scene, 'bookcaseLeft', -1.8);
createBookcase(scene, 'bookcaseRight', 1.8);
placeBooks(scene, left);
createFrontWall(scene);
lightRoom(scene);                                     // after all the meshes
const target = new BABYLON.Vector3(-0.8, 0.9, 1.2);
const camera = new BABYLON.ArcRotateCamera('inside', -1.3, 1.25, 3.9, target, scene);
camera.minZ = 0.05;
camera.attachControl(canvas, true);
engine.runRenderLoop(() => scene.render());
addEventListener('resize', () => engine.resize());
</script>