getProgram() turns the material, lights, fog and renderer settings into a cache key: the shader ID, the defines, about fifty values (precision, color space, UV channels, light counts), bit masks of 49 on-off features (fog, shadows, tone mapping...) and material.customProgramCacheKey(). Equal keys share one WebGLProgram; a new key means generating GLSL, compiling and linking. Colors and other uniforms change for free:
import * as THREE from 'three';
import * as BN from './bookshelf.js';
const stage = BN.createStage({ width: 320, height: 200 });
const { renderer, scene, camera } = stage;
const bookcase = BN.createBookcase();
scene.add(bookcase);
BN.lightBookcase(stage);
const frame = (label) => {
const start = performance.now();
renderer.render(scene, camera);
console.log(label.padEnd(13), (performance.now() - start).toFixed(0).padStart(4), 'ms,',
renderer.info.programs.length, 'programs');
};
frame('first frame');
frame('second frame');
bookcase.getObjectByName('The Quiet Harbor').material.forEach((m) => {
BN.addSaturation(m, { value: 0.2 });
m.needsUpdate = true; // else the cached program stays
});
frame('patched');
scene.fog = new THREE.Fog('#eceff1', 2, 8);
frame('fog added');
window.__done = true;Output
first frame 360 ms, 6 programs second frame 2 ms, 6 programs patched 388 ms, 8 programs fog added 724 ms, 12 programs
Compiling cost the first frame 360 ms (ANGLE 2,592 also translates to Direct3D). Each entry of info.programs has a usedTimes: the 26 materials share two programs (14 untextured, 12 textured), plus one for the shadow pass; the other three are RoomEnvironment's. The default customProgramCacheKey() is onBeforeCompile's source, so the patch made two variants, but only after needsUpdate (Question 8 in Test Yourself!). Fog changed every lit material's key: settle fog, shadows and tone mapping early, and precompile with await renderer.compileAsync(scene, camera) behind a loading screen.
<!doctype html>
<style>
body { margin: 0; background: #f5f1e8; font: 12px system-ui, sans-serif; color: #263238; }
.row { display: flex; gap: 8px; flex-wrap: wrap; align-items: flex-start; padding: 4px; }
canvas { display: block; }
table { border-collapse: collapse; background: #fff; }
td, th { border: 1px solid #ddd; padding: 3px 6px; text-align: right; }
td:first-child, th:first-child { text-align: left; }
.ui { padding: 4px 8px; }
</style>
<script type="importmap">
{ "imports": {
"three": "https://cdn.jsdelivr.net/npm/three@0.186.1/build/three.module.js",
"three/addons/": "https://cdn.jsdelivr.net/npm/three@0.186.1/examples/jsm/" } }
</script>
<div class="ui"><button id="color">Recolor a book (uniform)</button> <button id="patch">Patch a material</button> <button id="fog">Add fog</button></div>
<div class="row" id="row"><table id="t"><tr><th>frame</th><th>ms</th><th>programs</th></tr></table></div>
<script type="module">
import * as THREE from 'three';
import { mergeGeometries } from 'three/addons/utils/BufferGeometryUtils.js';
import { RoomEnvironment } from 'three/addons/environments/RoomEnvironment.js';
const BOOKS = [
{ title: 'The Quiet Harbor', author: 'Elena Marsh', color: '#1f5f8b', rating: 4.6, pages: 312 },
{ title: 'Patterns of the Deep Web', author: 'Ravi Menon', color: '#5b3f99', rating: 4.3, pages: 428 },
{ title: 'Salt and Saffron', author: 'Leila Haddad', color: '#e09a10', rating: 4.8, pages: 256 },
{ title: 'Small Steps to Big Summits', author: 'Tom Okafor', color: '#3f7d3a', rating: 4.1, pages: 198 },
{ title: "The Clockmaker's Paradox", author: 'Iris Vale', color: '#b5452f', rating: 4.5, pages: 344 },
{ title: 'Gardens in Glass', author: 'June Park', color: '#2a9d8f', rating: 4.4, pages: 176 },
];
// --- Book model: pages, two boards and a curved spine, merged with one group per part ---
const thickness = (book) => 0.05 + book.pages * 0.0003; // metres, from the page count
function bookGeometry(book, height, depth = 0.62) {
const t = thickness(book), b = 0.012, y = height / 2, z = -depth / 2;
const box = (w, h, d, x, zz = z) => new THREE.BoxGeometry(w, h, d).translate(x, y, zz);
const spine = new THREE.CylinderGeometry(t / 2, t / 2, height, 24, 1, true, -Math.PI / 2, Math.PI)
.scale(1, 1, 0.5).translate(0, y, 0);
return mergeGeometries([box(t - 2 * b, height - 0.03, depth - 0.02, 0, z + 0.01),
box(b, height, depth, (b - t) / 2), box(b, height, depth, (t - b) / 2), spine], true);
}
function paint(book, width, height, draw) {
const canvas = Object.assign(document.createElement('canvas'), { width, height });
const g = canvas.getContext('2d');
g.fillStyle = book.color; g.fillRect(0, 0, width, height);
g.fillStyle = '#ffffff';
draw(g);
const texture = new THREE.CanvasTexture(canvas);
texture.colorSpace = THREE.SRGBColorSpace;
return texture;
}
const coverArt = (book) => paint(book, 360, 520, (g) => {
g.font = 'bold 50px Georgia, serif';
book.title.split(' ').forEach((word, i) => g.fillText(word, 28, 84 + i * 56, 304));
g.font = 'italic 28px Georgia, serif';
g.fillText(`${book.author}, ${book.rating} / 5`, 28, 460);
});
const spineArt = (book) => paint(book, 128, 640, (g) => {
g.rotate(Math.PI / 2);
g.textBaseline = 'middle';
g.font = 'bold 44px Georgia, serif';
g.fillText(book.title, 24, -64, 440);
g.font = '28px Georgia, serif';
g.fillText(book.author.split(' ').at(-1), 490, -64, 130);
});
function createSpineBook(book, height = 0.9) {
const material = (options) => new THREE.MeshStandardMaterial({ roughness: 0.6, ...options });
const mesh = new THREE.Mesh(bookGeometry(book, height), [material({ color: '#f3ecdc' }),
material({ color: book.color }), material({ map: coverArt(book) }), material({ map: spineArt(book) })]);
return Object.assign(mesh, { name: book.title, userData: { book } });
}
// --- The arrangement ---
function createBookcase() {
const bookcase = new THREE.Group();
const plank = new THREE.Mesh(new THREE.BoxGeometry(3.5, 0.06, 0.8), new THREE.MeshStandardMaterial({ color: '#8d6e63' }));
plank.name = 'plank';
plank.position.set(0, -0.52, 0);
bookcase.add(plank);
const top = BOOKS.reduce((best, book) => (book.rating > best.rating ? book : best));
let x = -0.85;
BOOKS.forEach((book, i) => {
const mesh = createSpineBook(book, 0.84 + 0.05 * (i % 3)); // three trim heights
if (book === top) {
mesh.position.set(0.3, -0.49, 0.05);
mesh.rotation.y = -Math.PI / 2 + 0.35; // cover forward, turned a little
} else {
mesh.position.set(x + thickness(book) / 2, -0.49, 0.3); // running x plus half a thickness
x += thickness(book) + 0.005;
}
bookcase.add(mesh);
});
return bookcase;
}
// --- Stage and lighting: sun and hemisphere, RoomEnvironment fill, Neutral tone mapping, shadows ---
function createStage(width, height, renderer = new THREE.WebGLRenderer({ antialias: true })) {
renderer.setPixelRatio(Math.min(devicePixelRatio, 2));
renderer.setSize(width, height);
document.body.prepend(renderer.domElement);
const scene = new THREE.Scene();
scene.background = new THREE.Color('#eceff1');
const camera = new THREE.PerspectiveCamera(35, width / height, 0.1, 50);
scene.add(new THREE.HemisphereLight('#ffffff', '#8d6e63', 1));
const sun = new THREE.DirectionalLight('#ffffff', 2.5);
sun.name = 'sun';
scene.add(sun);
return { renderer, scene, camera };
}
function lightBookcase({ renderer, scene, camera }, PMREM = THREE.PMREMGenerator) {
renderer.toneMapping = THREE.NeutralToneMapping;
const pmrem = new PMREM(renderer);
scene.environment = pmrem.fromScene(new RoomEnvironment(), 0.04).texture;
scene.environmentIntensity = 0.5;
pmrem.dispose();
const wall = new THREE.Mesh(new THREE.PlaneGeometry(12, 6), new THREE.MeshStandardMaterial({ color: '#eceff1' }));
wall.name = 'wall';
wall.position.set(0, 1, -0.45);
scene.add(wall);
renderer.shadowMap.enabled = true;
const sun = scene.getObjectByName('sun');
sun.castShadow = true;
sun.shadow.mapSize.set(1024, 1024);
sun.shadow.normalBias = 0.02;
Object.assign(sun.shadow.camera, { left: -2, right: 2, top: 1.5, bottom: -1.5 });
scene.traverse((o) => { if (o.isMesh) o.castShadow = o.receiveShadow = true; });
sun.position.set(-1.5, 3, 4); // light from the left, shadows fall right
camera.position.set(0.15, 0.45, 2.75);
camera.lookAt(-0.1, -0.05, 0);
}
const stage = createStage(330, 230);
document.getElementById('row').prepend(stage.renderer.domElement);
const { renderer, scene, camera } = stage;
const bookcase = createBookcase();
scene.add(bookcase);
lightBookcase(stage);
camera.position.set(0.1, 0.5, 3.6);
// Time one render() and count the compiled programs
function frame(label) {
const start = performance.now();
renderer.render(scene, camera);
const ms = performance.now() - start;
document.getElementById('t').insertAdjacentHTML('beforeend',
`<tr><td>${label}</td><td>${ms.toFixed(0)}</td><td>${renderer.info.programs.length}</td></tr>`);
}
const harbor = bookcase.getObjectByName('The Quiet Harbor');
document.getElementById('color').onclick = () => {
harbor.material[1].color.setHSL(Math.random(), 0.5, 0.4); // a uniform: no new program
frame('recolored');
};
document.getElementById('patch').onclick = () => {
harbor.material.forEach((m) => {
m.onBeforeCompile = (shader) => { // changes the shader source...
shader.fragmentShader = shader.fragmentShader.replace('#include <map_fragment>',
'#include <map_fragment>\n diffuseColor.rgb = vec3(dot(diffuseColor.rgb, vec3(0.2126, 0.7152, 0.0722)));');
};
m.needsUpdate = true; // ...but only after needsUpdate
});
frame('patched');
};
document.getElementById('fog').onclick = () => {
scene.fog = new THREE.Fog('#eceff1', 2, 8); // fog is part of every lit material's key
frame('fog added');
};
frame('first frame'); // compiles everything
frame('second frame'); // all cached
document.getElementById('color').click();
document.getElementById('patch').click();
document.getElementById('fog').click();
</script>