Raycaster

• setFromCamera(coords, camera) expects NDC coordinates with x and y between -1 and 1.
• intersectObjects(list, true) tests descendants and returns hits sorted by distance.
• instanceId identifies which instance of an InstancedMesh was hit.

const raycaster = new THREE.Raycaster();
const pointer = new THREE.Vector2();
const targets = [];   // 只放需要参与拾取的对象

renderer.domElement.addEventListener('pointerdown', function (event) {
  const rect = renderer.domElement.getBoundingClientRect();
  pointer.x = ((event.clientX - rect.left) / rect.width) * 2 - 1;
  pointer.y = -((event.clientY - rect.top) / rect.height) * 2 + 1;

  raycaster.setFromCamera(pointer, camera);
  const hits = raycaster.intersectObjects(targets, false);

  if (!hits.length) return;
  console.log(hits[0].object.name, hits[0].point.toArray());
});

const ground = new THREE.Plane(new THREE.Vector3(0, 1, 0), 0); // y = 0
const hitPoint = new THREE.Vector3();

raycaster.setFromCamera(pointer, camera);
const ok = raycaster.ray.intersectPlane(ground, hitPoint);
if (ok) marker.position.copy(hitPoint);

• An unnormalized direction distorts distances and threshold tests; call normalize().
• Hit records carry no feature attributes; map them through object.userData yourself.