raycaster:pick

pick & place

by jason870509

HTML

<div id="info">Pick & Place</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/84/three.min.js"></script>
<script src="https://threejs.org/examples/js/controls/OrbitControls.js">


</script>

CSS

#info {
  position: absolute;
  top: 0px;
  width: 100%;
  padding: 10px;
  text-align: center;
  color: #ffff00
}

body {
  overflow: hidden
}

JavaScript

var camera, scene, renderer, controls;
var puck;

var raycaster;
var mouse = new THREE.Vector2();
var pickables = [];

init();
animate();

function init() {
  scene = new THREE.Scene();

  camera = new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 1000);
  camera.position.z = 500;

  var gridXZ = new THREE.GridHelper(240, 24, 'red', 'white');
  scene.add(gridXZ);

  renderer = new THREE.WebGLRenderer();
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.setClearColor(0x888888);

  controls = new THREE.OrbitControls(camera, renderer.domElement);

  document.body.appendChild(renderer.domElement);

  /////////////////////////////////////////////////////////////////////
  plane = new THREE.Mesh(new THREE.PlaneGeometry(200, 200), new THREE.MeshBasicMaterial({
    transparent: true,
    opacity: 0.5,
    visible: true
  }));
  scene.add(plane);
  plane.rotation.x = -Math.PI / 2;
  pickables = [plane];

  puck = new THREE.Mesh(new THREE.CylinderGeometry(10, 10, 2, 20), new THREE.MeshNormalMaterial());
  scene.add(puck);

  raycaster = new THREE.Raycaster();
  document.addEventListener('mousedown', onDocumentMouseDown, false);
}

function onDocumentMouseDown(event) {

  // PICKING DETAILS: 
  // convert mouse.xy = [-1,1]^2 (NDC)
  // unproject (mouse.xy, 1) to a point on the far plane (in world coordinate)
  // set raycaster (origin, direction)
  // find intersection objects, (closest first) 
  // each record as
  // [ { distance, point, face, faceIndex, object }, ... ]

  event.preventDefault();
  mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
  mouse.y = -(event.clientY / window.innerHeight) * 2 + 1;

  // find intersections
  raycaster.setFromCamera(mouse, camera);
  var intersects = raycaster.intersectObjects(pickables);
  if (intersects.length > 0) {
    puck.position.copy(intersects[0].point);
  }

}

function animate() {
  controls.update();
  requestAnimationFrame(animate);
  render();
}

function render() {
 ...