LearnSpace: full-stack educational whiteboard platform
Node.js/Express backend + vanilla JS frontend. Features: real-time collaborative whiteboard (SSE), multi-page support, LaTeX formulas, shapes/connectors, coordinate systems, number lines, compass, zoom/pan, Catmull-Rom pencil smoothing, ruler/protractor with rotation & resize controls, minimap navigation overlay, auto-measurements, multi-page thumbnails sidebar, PNG export, page templates. Student/teacher workflows: classes, assignments, library, dashboard. Mobile responsive. SQLite (better-sqlite3). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Maxim Dolgolyov
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'use strict';
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/* ═══════════════════════════════════════════════
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CrystalSim — 3D crystal lattice (Three.js)
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NaCl, Diamond, BCC metal, FCC metal
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═══════════════════════════════════════════════ */
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class CrystalSim {
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constructor(container) {
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this.container = container;
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this._running = false;
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/* Three.js */
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this.scene = new THREE.Scene();
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this.camera = new THREE.PerspectiveCamera(50, 1, 0.1, 200);
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this.renderer = new THREE.WebGLRenderer({ antialias: true, alpha: true });
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this.renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
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this.renderer.setClearColor(0x0D0D1A, 1);
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container.appendChild(this.renderer.domElement);
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/* lighting */
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this.scene.add(new THREE.AmbientLight(0xffffff, 0.5));
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const dir = new THREE.DirectionalLight(0xffffff, 0.8);
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dir.position.set(5, 8, 6);
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this.scene.add(dir);
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const pt = new THREE.PointLight(0x9B5DE5, 0.4, 50);
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pt.position.set(-4, 3, 5);
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this.scene.add(pt);
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this.camera.position.set(8, 6, 8);
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this.camera.lookAt(0, 0, 0);
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/* orbit-like manual controls */
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this._drag = false;
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this._prevX = 0;
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this._prevY = 0;
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this._rotY = 0.6;
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this._rotX = 0.4;
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this._dist = 12;
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this._autoSpin = true;
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const el = this.renderer.domElement;
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el.style.cursor = 'grab';
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el.addEventListener('pointerdown', e => { this._drag = true; this._prevX = e.clientX; this._prevY = e.clientY; this._autoSpin = false; el.style.cursor = 'grabbing'; });
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window.addEventListener('pointerup', () => { this._drag = false; el.style.cursor = 'grab'; });
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window.addEventListener('pointermove', e => {
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if (!this._drag) return;
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this._rotY += (e.clientX - this._prevX) * 0.008;
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this._rotX += (e.clientY - this._prevY) * 0.008;
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this._rotX = Math.max(-1.4, Math.min(1.4, this._rotX));
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this._prevX = e.clientX; this._prevY = e.clientY;
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});
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el.addEventListener('wheel', e => {
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e.preventDefault();
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this._dist = Math.max(5, Math.min(30, this._dist + e.deltaY * 0.02));
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}, { passive: false });
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/* touch */
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el.addEventListener('touchstart', e => {
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if (e.touches.length === 1) {
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this._drag = true; this._prevX = e.touches[0].clientX; this._prevY = e.touches[0].clientY; this._autoSpin = false;
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}
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}, { passive: true });
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el.addEventListener('touchmove', e => {
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if (!this._drag || e.touches.length !== 1) return;
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const t = e.touches[0];
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this._rotY += (t.clientX - this._prevX) * 0.008;
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this._rotX += (t.clientY - this._prevY) * 0.008;
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this._rotX = Math.max(-1.4, Math.min(1.4, this._rotX));
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this._prevX = t.clientX; this._prevY = t.clientY;
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}, { passive: true });
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el.addEventListener('touchend', () => { this._drag = false; });
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/* resize */
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this._ro = new ResizeObserver(() => this.fit());
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this._ro.observe(container);
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/* state */
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this._lattice = 'nacl';
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this._group = new THREE.Group();
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this.scene.add(this._group);
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this._buildLattice('nacl');
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this.fit();
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this.play();
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}
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/* ── public ── */
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setLattice(type) {
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this._lattice = type;
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this._buildLattice(type);
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}
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fit() {
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const w = this.container.clientWidth || 600;
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const h = this.container.clientHeight || 400;
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this.camera.aspect = w / h;
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this.camera.updateProjectionMatrix();
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this.renderer.setSize(w, h);
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}
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play() { if (!this._running) { this._running = true; this._loop(); } }
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stop() { this._running = false; }
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pause() { this._running = false; }
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/* ── lattice builders ── */
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_buildLattice(type) {
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// clear
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while (this._group.children.length) {
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const c = this._group.children[0];
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c.geometry?.dispose(); c.material?.dispose();
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this._group.remove(c);
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}
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const builders = {
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nacl: () => this._buildNaCl(),
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diamond: () => this._buildDiamond(),
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bcc: () => this._buildBCC(),
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fcc: () => this._buildFCC(),
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};
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(builders[type] || builders.nacl)();
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}
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_sphere(r, color) {
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const geo = new THREE.SphereGeometry(r, 24, 24);
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const mat = new THREE.MeshPhysicalMaterial({
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color, metalness: 0.1, roughness: 0.3,
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clearcoat: 0.6, clearcoatRoughness: 0.2,
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});
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return new THREE.Mesh(geo, mat);
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}
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_bond(from, to, color = 0x555555) {
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const dir = new THREE.Vector3().subVectors(to, from);
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const len = dir.length();
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const geo = new THREE.CylinderGeometry(0.04, 0.04, len, 8);
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const mat = new THREE.MeshStandardMaterial({ color, opacity: 0.5, transparent: true });
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const mesh = new THREE.Mesh(geo, mat);
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mesh.position.copy(from).add(dir.multiplyScalar(0.5));
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mesh.quaternion.setFromUnitVectors(new THREE.Vector3(0, 1, 0), dir.normalize());
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return mesh;
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}
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_buildNaCl() {
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const n = 3; // 3×3×3 unit cells
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const a = 2.0; // lattice constant
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const offset = -(n - 1) * a / 2;
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const positions = [];
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for (let i = 0; i < n; i++)
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for (let j = 0; j < n; j++)
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for (let k = 0; k < n; k++) {
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const x = offset + i * a, y = offset + j * a, z = offset + k * a;
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const isNa = (i + j + k) % 2 === 0;
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const s = this._sphere(isNa ? 0.28 : 0.38, isNa ? 0x9B5DE5 : 0x06D6E0);
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s.position.set(x, y, z);
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this._group.add(s);
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positions.push({ x, y, z });
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}
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// bonds to nearest neighbors
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for (let i = 0; i < positions.length; i++)
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for (let j = i + 1; j < positions.length; j++) {
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const dx = positions[i].x - positions[j].x;
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const dy = positions[i].y - positions[j].y;
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const dz = positions[i].z - positions[j].z;
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const d2 = dx * dx + dy * dy + dz * dz;
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if (Math.abs(d2 - a * a) < 0.01) {
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const b = this._bond(
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new THREE.Vector3(positions[i].x, positions[i].y, positions[i].z),
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new THREE.Vector3(positions[j].x, positions[j].y, positions[j].z),
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0x444466
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);
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this._group.add(b);
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}
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}
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}
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_buildDiamond() {
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const a = 2.5;
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const basis = [
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[0, 0, 0], [0.5, 0.5, 0], [0.5, 0, 0.5], [0, 0.5, 0.5],
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[0.25, 0.25, 0.25], [0.75, 0.75, 0.25], [0.75, 0.25, 0.75], [0.25, 0.75, 0.75],
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];
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const n = 2;
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const offset = -(n * a) / 2;
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const allPos = [];
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for (let ci = 0; ci < n; ci++)
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for (let cj = 0; cj < n; cj++)
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for (let ck = 0; ck < n; ck++)
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for (const [bx, by, bz] of basis) {
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const x = offset + (ci + bx) * a;
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const y = offset + (cj + by) * a;
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const z = offset + (ck + bz) * a;
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const s = this._sphere(0.22, 0x34d399);
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s.position.set(x, y, z);
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this._group.add(s);
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allPos.push(new THREE.Vector3(x, y, z));
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}
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// bonds
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const bondLen = a * Math.sqrt(3) / 4;
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const tol = bondLen * 0.15;
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for (let i = 0; i < allPos.length; i++)
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for (let j = i + 1; j < allPos.length; j++) {
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const d = allPos[i].distanceTo(allPos[j]);
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if (Math.abs(d - bondLen) < tol) {
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this._group.add(this._bond(allPos[i], allPos[j], 0x228866));
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}
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}
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}
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_buildBCC() {
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const a = 2.2, n = 3;
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const offset = -(n - 1) * a / 2;
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const allPos = [];
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for (let i = 0; i < n; i++)
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for (let j = 0; j < n; j++)
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for (let k = 0; k < n; k++) {
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// corner atoms
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const x1 = offset + i * a, y1 = offset + j * a, z1 = offset + k * a;
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const s1 = this._sphere(0.3, 0xF15BB5);
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s1.position.set(x1, y1, z1);
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this._group.add(s1);
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allPos.push(new THREE.Vector3(x1, y1, z1));
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// body center (except last cell in each dimension)
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if (i < n - 1 && j < n - 1 && k < n - 1) {
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const cx = x1 + a / 2, cy = y1 + a / 2, cz = z1 + a / 2;
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const s2 = this._sphere(0.3, 0xF59E0B);
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s2.position.set(cx, cy, cz);
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this._group.add(s2);
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allPos.push(new THREE.Vector3(cx, cy, cz));
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}
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}
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// bonds
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const bondLen = a * Math.sqrt(3) / 2;
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const tol = bondLen * 0.1;
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for (let i = 0; i < allPos.length; i++)
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for (let j = i + 1; j < allPos.length; j++) {
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const d = allPos[i].distanceTo(allPos[j]);
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if (Math.abs(d - bondLen) < tol) {
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this._group.add(this._bond(allPos[i], allPos[j], 0x664444));
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}
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}
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}
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_buildFCC() {
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const a = 2.4, n = 3;
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const offset = -(n - 1) * a / 2;
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const allPos = [];
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for (let i = 0; i < n; i++)
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for (let j = 0; j < n; j++)
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for (let k = 0; k < n; k++) {
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const x = offset + i * a, y = offset + j * a, z = offset + k * a;
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// corner
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const s = this._sphere(0.25, 0x60a5fa);
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s.position.set(x, y, z);
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this._group.add(s);
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allPos.push(new THREE.Vector3(x, y, z));
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// face centers (only for cell interiors)
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if (i < n - 1 && j < n - 1) {
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const f1 = this._sphere(0.25, 0x60a5fa);
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f1.position.set(x + a / 2, y + a / 2, z);
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this._group.add(f1);
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allPos.push(new THREE.Vector3(x + a / 2, y + a / 2, z));
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}
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if (i < n - 1 && k < n - 1) {
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const f2 = this._sphere(0.25, 0x60a5fa);
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f2.position.set(x + a / 2, y, z + a / 2);
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this._group.add(f2);
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allPos.push(new THREE.Vector3(x + a / 2, y, z + a / 2));
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}
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if (j < n - 1 && k < n - 1) {
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const f3 = this._sphere(0.25, 0x60a5fa);
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f3.position.set(x, y + a / 2, z + a / 2);
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this._group.add(f3);
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allPos.push(new THREE.Vector3(x, y + a / 2, z + a / 2));
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}
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}
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// bonds to nearest neighbors (a/√2)
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const bondLen = a / Math.SQRT2;
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const tol = bondLen * 0.1;
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for (let i = 0; i < allPos.length; i++)
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for (let j = i + 1; j < allPos.length; j++) {
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const d = allPos[i].distanceTo(allPos[j]);
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if (Math.abs(d - bondLen) < tol) {
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this._group.add(this._bond(allPos[i], allPos[j], 0x334466));
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}
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}
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}
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/* ── animation ── */
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_loop() {
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if (!this._running) return;
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requestAnimationFrame(() => this._loop());
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if (this._autoSpin) this._rotY += 0.003;
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this.camera.position.set(
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this._dist * Math.sin(this._rotY) * Math.cos(this._rotX),
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this._dist * Math.sin(this._rotX),
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this._dist * Math.cos(this._rotY) * Math.cos(this._rotX)
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);
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this.camera.lookAt(0, 0, 0);
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this.renderer.render(this.scene, this.camera);
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}
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}
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