Pointer Observables

Pointer Observables and Event Types

scene.onPointerObservable reports every pointer event (mouse, touch and pen through the Pointer Events API) as PointerInfo: a type from BABYLON.PointerEventTypes, the DOM event, and a pickInfo for the mesh under the pointer; a second argument filters types as a bit mask. On ActionManager's shelf:

Logging the pointer events of one simulated clickJavaScript
const { POINTERDOWN, POINTERUP, POINTERPICK, POINTERTAP } = BABYLON.PointerEventTypes;
console.log(`down ${POINTERDOWN}, up ${POINTERUP}, pick ${POINTERPICK}, tap ${POINTERTAP}`);
scene.onPointerObservable.add(({ type, pickInfo }) => console.log(type, pickInfo.pickedMesh.name));
const hit = scene.pick(view.clientWidth / 2, view.clientHeight / 2);
scene.simulatePointerMove(hit);                  // type 4, POINTERMOVE
scene.simulatePointerDown(hit);
scene.simulatePointerUp(hit);
Output
down 1, up 2, pick 16, tap 32
4 book3
1 book3
16 book3
2 book3
32 book3

POINTERPICK follows a down and up on one mesh, POINTERTAP a click without a drag, POINTERDOUBLETAP two quick taps. A real mouse move picks lazily and arrives without pickInfo (a dispatched DOM pointermove did here), so call scene.pick when you need it; onPrePointerObservable sees events before the camera does.

scene.onPointerObservable logging each PointerEventTypes value and the mesh under the pointerHTMLLive
<!doctype html>
<style>
  body { margin: 0; background: #f7f3ec; font: 13px system-ui, sans-serif; color: #333; }
  canvas { width: 100%; max-width: 600px; height: 260px; display: block; touch-action: none; outline: none; }
  #log { max-width: 600px; height: 118px; overflow: hidden; margin: 0; padding: 4px 8px; box-sizing: border-box; font: 12px monospace; background: #fff; }
</style>
<canvas id="view"></canvas>
<pre id="log"></pre>
<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 ----

const canvas = document.getElementById('view');
const engine = new BABYLON.Engine(canvas, true, {}, true);
const scene = createScene(engine);
const books = placeBooks(scene, createBookcase(scene, 'case', 0));
const camera = new BABYLON.ArcRotateCamera('browse', -Math.PI / 2, 1.5, 1.6, new BABYLON.Vector3(0, 1.3, 2.6), scene);
camera.minZ = 0.05;
camera.attachControl(canvas, true);
engine.runRenderLoop(() => scene.render());

// Name each numeric type: POINTERDOWN 1, POINTERUP 2, POINTERMOVE 4, POINTERWHEEL 8, POINTERPICK 16...
const TYPE_NAMES = Object.fromEntries(Object.entries(BABYLON.PointerEventTypes)
  .filter(([, value]) => typeof value === 'number').map(([name, value]) => [value, name]));
const lines = [];
const logLine = (text) => {
  lines.unshift(text);
  document.getElementById('log').textContent = lines.slice(0, 8).join('\n');
};
const highlight = new BABYLON.HighlightLayer('hover', scene);
const { POINTERMOVE, POINTERDOWN, POINTERUP, POINTERTAP, POINTERPICK, POINTERDOUBLETAP } = BABYLON.PointerEventTypes;
scene.onPointerObservable.add(({ type, pickInfo }) => {
  // a real mouse move picks lazily, so pick here when the mesh matters
  const hit = type === POINTERMOVE ? scene.pick(scene.pointerX, scene.pointerY) : pickInfo;
  const mesh = hit?.pickedMesh;
  if (type === POINTERMOVE) {
    highlight.removeAllMeshes();
    if (mesh?.metadata) highlight.addMesh(mesh, BABYLON.Color3.FromHexString('#ffe082'));
    return;                                          // too many to log
  }
  logLine(`${String(type).padStart(2)} ${TYPE_NAMES[type].padEnd(16)} ${mesh ? mesh.metadata?.title || mesh.name : '(nothing)'}`);
}, POINTERDOWN | POINTERUP | POINTERMOVE | POINTERTAP | POINTERPICK | POINTERDOUBLETAP);   // a bit mask

// One simulated click so the log has entries; then use the mouse
scene.executeWhenReady(() => {
  scene.render();
  const aim = books[4].getBoundingInfo().boundingBox.centerWorld.subtract(camera.position).normalize();
  const hit = scene.pickWithRay(new BABYLON.Ray(camera.position, aim));
  scene.simulatePointerDown(hit);
  scene.simulatePointerUp(hit);
});
addEventListener('resize', () => engine.resize());
</script>